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Schroedinger's Dog



Posts: 1691
Joined: Jan. 2009

(Permalink) Posted: April 18 2012,05:59   

I've noticed that there are very interesting photo talks in the Wildlife section, and some tidbits in other threads, but there doesn't seem to be a dedicated thread for all things photography. I understand it's not mandatory on such a forum, but since we have talentuous contributors, whether in photography or photoplasty, I just wanted to get past their modesty, show my own ignorance of the subject at large, and open this new thread.

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"Hail is made out of water? Are you really that stupid?" Joe G

"I have a better suggestion, Kris. How about a game of hide and go fuck yourself instead." Louis

"The reason people use a crucifix against vampires is that vampires are allergic to bullshit" Richard Pryor

   
oldmanintheskydidntdoit



Posts: 4999
Joined: July 2006

(Permalink) Posted: April 18 2012,06:58   

I'm a big fan of the micro four thirds range, DSLR level quality (sorta) but fits in your pocket.

20mm f1.7 = no flash required. But I got one anyway :)



I'll post some snaps later.

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I also mentioned that He'd have to give me a thorough explanation as to *why* I must "eat human babies".
FTK

if there are even critical flaws in Gauger’s work, the evo mat narrative cannot stand
Gordon Mullings

  
carlsonjok



Posts: 3324
Joined: May 2006

(Permalink) Posted: April 18 2012,08:03   

Well, my setup is a Canon EOS T2i matched to a Tamron DiII 18-270mm travel lens.  I'd like to get something with a little faster continuous shooting (the T2i is only 3.7 fps), but I'm not ready to shell out the greenbacks right now.

This is probably my favorite picture. I realize it is more than a little derivative, but I like it anyways.



ETA: Lake Quanah Parker in the Wichita Mountains Wildlife Refuge.

Edited by carlsonjok on April 18 2012,08:04

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It's natural to be curious about our world, but the scientific method is just one theory about how to best understand it.  We live in a democracy, which means we should treat every theory equally. - Steven Colbert, I Am America (and So Can You!)

  
damitall



Posts: 324
Joined: Jan. 2009

(Permalink) Posted: April 18 2012,08:57   

Quote (carlsonjok @ April 18 2012,08:03)
Well, my setup is a Canon EOS T2i matched to a Tamron DiII 18-270mm travel lens.  I'd like to get something with a little faster continuous shooting (the T2i is only 3.7 fps), but I'm not ready to shell out the greenbacks right now.

This is probably my favorite picture. I realize it is more than a little derivative, but I like it anyways.



ETA: Lake Quanah Parker in the Wichita Mountains Wildlife Refuge.

Derivative, shmerivative.

I really LIKE that image

  
Lou FCD



Posts: 5379
Joined: Jan. 2006

(Permalink) Posted: April 18 2012,18:39   

Hey, cool idea, but how did *I* get roped into the name??

:-P

I'm shooting with a Canon 5D MkII, the kit lens (24-105mm f/4.0 L series), my birding lens (100-400mm f/4.5 - 5.6 L series), and my brand new 50mm f/1.2 L series prime.

I have a Canon EX580II flash, and a cheap set of 3 Neewer 300DI studio lights with sundry accessories.

A couple of non-wildlife things I've shot lately, from my website:



Best man at a wedding I shot for the sister of a friend (I so don't want to be a wedding photographer, but a couple of bucks in the pocket now and again is nice).



But besides birds, this is the kind of thing I like to do most:





The downer to that stuff is that usually I can't share the best shots.

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Lou FCD is still in school, so we should only count him as a baby biologist. -carlsonjok -deprecated
I think I might love you. Don't tell Deadman -Wolfhound

Work-friendly photography
NSFW photography

   
khan



Posts: 1486
Joined: May 2007

(Permalink) Posted: April 18 2012,19:15   

Can someone explain what that f.. stuff means?

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"It's as if all those words, in their hurry to escape from the loony, have fallen over each other, forming scrambled heaps of meaninglessness." -damitall

That's so fucking stupid it merits a wing in the museum of stupid. -midwifetoad

Frequency is just the plural of wavelength...
-JoeG

  
carlsonjok



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Joined: May 2006

(Permalink) Posted: April 18 2012,19:36   

Quote (khan @ April 18 2012,19:15)
Can someone explain what that f.. stuff means?

Well, when a man and woman love each other very much and want to make a baby.........

--------------
It's natural to be curious about our world, but the scientific method is just one theory about how to best understand it.  We live in a democracy, which means we should treat every theory equally. - Steven Colbert, I Am America (and So Can You!)

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 18 2012,20:11   

Quote (khan @ April 18 2012,19:15)
Can someone explain what that f.. stuff means?

f-stops are a measure of light-gathering or light transmission capability.

Start with a pinhole. A small hole will serve to produce an image. The closer it is to the image plane, the brighter the resulting image is. So for a fixed aperture, or size of hole, the distance from image plane to the pinhole can change the amount of light arriving at the image plane. For a pinhole, the distance from the image plane can be treated as the focal length. A smaller pinhole that is closer to the image plane and a larger pinhole that is further from the image plane will produce the same amount of light impinging on the image plane. You can, in fact, derive a formula for this equivalent light-passing capability:

f-stop = {focal length} / {diameter of aperture}

Small f-stop numbers indicate aperture diameters closer to the focal length. Larger f-stop numbers mean the aperture diameter is small relative to the focal length.

Now, pinholes have to have a high f-stop in order for the images produced to look anywhere near sharp. When we start thinking about lenses, these can be considered ways to make our pinholes larger without losing so much sharpness. The lens elements focus light paths diverging from a subject that touch all across their surface to (just about) one point. (If the lens is well-adjusted, etc.)

An f-stop is easily calculated and works for just about anything you put in front of a piece of film or a sensor. Handheld light meters for photography simply present shutter speed and aperture combinations to tell the measured light level, which is pretty impressive given how many different lenses have been produced over the history of man's use of optics.

But f-stops are not the whole story. Passing light through a complex lens with many elements will tend to lose a small amount of light to reflection at each surface encountered on the way in. Modern lenses have coatings on the surfaces to reduce this light loss. The cinematic folks tend to use lenses that have T-stop ratings. These are on the same scale as f-stops, but take into account the particular light loss that each lens has.

There are tradeoffs. Getting lower f-stop numbers and thus greater light-gathering capability requires larger pieces of glass and more esoteric means of correcting optical errors that refraction introduces into images. That means that "faster" glass is more expensive to make. A common "fast" f-stop is f/2.8, or a light-gathering element with an effective diameter just a bit larger than one-third the focal length. Once you get past f/5.6, certain features like autofocus tend not to work. Those need a certain amount of light to do their work. Lou's new lens is an f/1.2, an exceptionally fast lens. It will permit almost three stops or eight times as much light through it wide-open as will an f/2.8 lens.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 18 2012,20:47   

For folks using auto-focus and auto-exposure, the transmission factor of the glass is irrelevant, unless one brand is crappy compared to another.

Movie makers need to work like Ansel Adams and control the luminosity of ever element in the frame. Or at least know how it's going to look.

That's why actors sit around for hours sometimes, waiting for the light to get right.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
Henry J



Posts: 4115
Joined: Mar. 2005

(Permalink) Posted: April 18 2012,23:28   

Quote (carlsonjok @ April 18 2012,18:36)
Quote (khan @ April 18 2012,19:15)
Can someone explain what that f.. stuff means?

Well, when a man and woman love each other very much and want to make a baby.........

They go into a dark room and see what develops?

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 19 2012,00:16   

Quote (midwifetoad @ April 18 2012,20:47)
For folks using auto-focus and auto-exposure, the transmission factor of the glass is irrelevant, unless one brand is crappy compared to another.

Movie makers need to work like Ansel Adams and control the luminosity of ever element in the frame. Or at least know how it's going to look.

That's why actors sit around for hours sometimes, waiting for the light to get right.


That's a bit too glib. Unless you are using a Nikon D4, your 500mm f/8 mirror reflex lens would not autofocus even if it had autofocus capability. Autofocus modules stop working somewhere around f/5.6 to f/6.3. The D4 applies some of its high ISO capability to its autofocus module, which will accommodate lenses out to f/8.

This more commonly gets encountered when using teleconverters. A lens that will autofocus fine on its own will often fail to do so when you add a 2x teleconverter and essentially add 2 to its maximum f-stop. [ETA: That's unclear... you have to treat the lens as being two more f-stops slower, so an f/4 lens with a 2x teleconverter would be equivalent to an f/8 lens, while an f/5.6 lens would be equivalent to an f/11 lens.]

Autoexposure shouldn't have that working limit, but you do have to account for other transmission losses if you want to use handheld light meters that aren't tied into the optical system at issue and are using sensors or emulsions with limited dynamic range. Losing a half-stop or more of accuracy simply is not acceptable under critical use conditions. Calibration is essential then, and that is what Ansel Adams was famous for in his advocacy of the Zone System.

Edited by Wesley R. Elsberry on April 19 2012,00:31

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
Lou FCD



Posts: 5379
Joined: Jan. 2006

(Permalink) Posted: April 19 2012,07:44   

Quote (carlsonjok @ April 18 2012,09:03)
Well, my setup is a Canon EOS T2i matched to a Tamron DiII 18-270mm travel lens.  I'd like to get something with a little faster continuous shooting (the T2i is only 3.7 fps), but I'm not ready to shell out the greenbacks right now.

This is probably my favorite picture. I realize it is more than a little derivative, but I like it anyways.



ETA: Lake Quanah Parker in the Wichita Mountains Wildlife Refuge.

It's a sweet shot, Carlson. Did you slap any HDR on that, or is that a single shot?

I've been playing a little bit with HDR (Photomatrix Pro on some throw-away landscape shots), but I haven't yet really gotten the hang of it.

I did go out and shoot some dead cypress trees for a PhD candidate in my lab for a poster he did regarding his research on salt-water intrusion, and they came out great on his poster (and I got a photo credit, yay!).

This is an HDR composite and a mosaic of about 9 shots total from that excursion.



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Lou FCD is still in school, so we should only count him as a baby biologist. -carlsonjok -deprecated
I think I might love you. Don't tell Deadman -Wolfhound

Work-friendly photography
NSFW photography

   
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 19 2012,13:57   

Quote
That's a bit too glib.


I mentioned autofocus, but it wasn't really part of my argument.

I was addressing autoexposure, which works regardless of whether the lens aperture is calibrated correctly. With a digital camera you can have it do auto bracketing, and if you shoot RAW, you generally have enough latitude to make a good image, except in the most contrasty situations.

And if you are in that situation, HDR is the way to go.

Of course moving subjects and fleeting opportunities can make a hash of this, in which case you're stuck with autoexposure.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
Schroedinger's Dog



Posts: 1691
Joined: Jan. 2009

(Permalink) Posted: April 19 2012,18:28   

I'm still trying to convince Ali to sign up here and join the discussion. She loves photograpy and has a Canon 1000something with two gunbarrel-looking stuff to attach to it and seems to know about them (although I believe she's just pretending just to look smug). She's a frequent onlooker.

Lou, this thread is dedicated to you because you had a happy dance, and other than Katrine (and Louis), I don't know many that do.

Wes, I would love some schematics :)

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"Hail is made out of water? Are you really that stupid?" Joe G

"I have a better suggestion, Kris. How about a game of hide and go fuck yourself instead." Louis

"The reason people use a crucifix against vampires is that vampires are allergic to bullshit" Richard Pryor

   
carlsonjok



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Joined: May 2006

(Permalink) Posted: April 19 2012,20:13   

Quote (Lou FCD @ April 19 2012,07:44)
It's a sweet shot, Carlson. Did you slap any HDR on that, or is that a single shot?

That was a single shot.  Straight out of the camera it didn't have that much contrast.  Most of the effect was from post-processing.

Original:



I adjusted the white and black point in Photoshop to add some contrast.



I then put a black and white layer on top of that.



Then cranked down the blues and reds, and bumped up the yellows to get the final product.



It was a bit of a cheat.  The ominous feeling of the final product really wasn't there at the start.

--------------
It's natural to be curious about our world, but the scientific method is just one theory about how to best understand it.  We live in a democracy, which means we should treat every theory equally. - Steven Colbert, I Am America (and So Can You!)

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 19 2012,21:07   

Quote (midwifetoad @ April 19 2012,13:57)
Quote
That's a bit too glib.


I mentioned autofocus, but it wasn't really part of my argument.

I was addressing autoexposure, which works regardless of whether the lens aperture is calibrated correctly. With a digital camera you can have it do auto bracketing, and if you shoot RAW, you generally have enough latitude to make a good image, except in the most contrasty situations.

And if you are in that situation, HDR is the way to go.

Of course moving subjects and fleeting opportunities can make a hash of this, in which case you're stuck with autoexposure.

I'm not sure what you think there is an argument about.

Let's look at what I responded to:

Quote

Can someone explain what that f.. stuff means?


Care to tell me how "Pay no attention to that, autoexposure will take care of it" counts as an explanation, or even a contribution to an explanation?

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
midwifetoad



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Joined: Mar. 2008

(Permalink) Posted: April 19 2012,21:42   

You provided and explanation and I posted a comment to the effect that the difference between f-stop and t-stop have little practical implication when using an autoexposure camera.

If you were using a photometer or standalone light meter it would make a difference, but TTL metering doesn't care what the f-stop is.

I wasn't trying to explain; just commenting on the practical implications.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 19 2012,22:06   

Quote (midwifetoad @ April 19 2012,21:42)
You provided and explanation and I posted a comment to the effect that the difference between f-stop and t-stop have little practical implication when using an autoexposure camera.

If you were using a photometer or standalone light meter it would make a difference, but TTL metering doesn't care what the f-stop is.

I wasn't trying to explain; just commenting on the practical implications.

You have a weird way of expressing, "I agree."

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 19 2012,22:27   

I wasn't trying to agree or disagree. Just adding what I thought was a useful comment.

I've been around cameras for a few years. I still have a working Nikon F bought in 1965. I was a darkroom technician for four college yearbooks and made the final prints for three. I never used a camera with any automatic features for the first ten years I was in the hobby.

I sold darkroom equipment at Altman Camera in Chicago in 1970 and 71. At the time it was the largest camera store in the world.

Your explanation is fine. I learned something from the discussion of t-stops. I just thought it left the impression that the effective f-stop is something to be concerned about, and I doubt that it is.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
fusilier



Posts: 216
Joined: Feb. 2003

(Permalink) Posted: April 20 2012,07:06   

I'm an old film/chemistry guy, and my Pavlovian conditioning says "zoom lenses BAD!*"


I DO have a question on digital cameras, though.  I came across a Bass Rumoure that DSLRs have serious problems with dust on the CCD.  In particular, the electrostatic charge never goes away, and is not fixable.

I'm thinking of going to either a Canon G12 or Nikon equivalent, because you never open the camera body.




* Think Canon VI-T rangefinder with a Nikkor 85mm f/2 lens.  You can drive tent pegs with it.

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fusilier
James 2:24

  
Schroedinger's Dog



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Joined: Jan. 2009

(Permalink) Posted: April 20 2012,07:17   

I'll take the liberty of pasting here a PM I sent to Lou quite a while ago about astronomic photography with a numeric camera.

Any and all corrections are welcome:

Quote
All you need is your digicam, a stable stand, Photoshop, and a clear night sky.

You will have to set the apperture time of your cam to something akin to a normal low-light shooting (sadly I don't have the exact ms timing, but a few tests should let you figure it out). If the exposure time is too long, you'll get weird artefacts due to the Earth rotation, which the stand doesn't compensate.

Choose a patch of sky you'd like to imortalise, and start shooting. A remote would be better than actually pushing the button every time. That way you are sure your cam will be aligned 100% of the time.

Take as many pics as you want (usually 10 is enough).

Now, open these 10 (or more) pics in Photoshop (or any other software that works with layer). That's the tricky part. The bottom layer (ie. first pic) will be 100% opacity. all other pics will be added on a new layer, with oppacity decreasing by 10% for each new layer. So if you took 20 pics, it will decrease by 5%, but you should know that, Mr PhD

Take any single star or body from the bottom-layer pic, and use it to align all the pics, thus compensating Earth's rotation.

You should come up with amazing images. My favorite, when I used to work on this, was the Milky Way, but Andromeda gives great results as well.

Everything is in the setting of your exposure time, so a few trials and errors are nescessary.

Hope this help, and if it does, please share your pics


--------------
"Hail is made out of water? Are you really that stupid?" Joe G

"I have a better suggestion, Kris. How about a game of hide and go fuck yourself instead." Louis

"The reason people use a crucifix against vampires is that vampires are allergic to bullshit" Richard Pryor

   
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 20 2012,07:38   

Quote (midwifetoad @ April 19 2012,22:27)
I wasn't trying to agree or disagree. Just adding what I thought was a useful comment.

I've been around cameras for a few years. I still have a working Nikon F bought in 1965. I was a darkroom technician for four college yearbooks and made the final prints for three. I never used a camera with any automatic features for the first ten years I was in the hobby.

I sold darkroom equipment at Altman Camera in Chicago in 1970 and 71. At the time it was the largest camera store in the world.

Your explanation is fine. I learned something from the discussion of t-stops. I just thought it left the impression that the effective f-stop is something to be concerned about, and I doubt that it is.

Since the whole point of f-stops is supposed to be a metric of light transmission that is the same across disparate lenses, the explanation would be incomplete without discussion of how the simple f-stop metric isn't sufficient for that objective. That's still true whether current TTL metering makes deep knowledge of light transmission in optics moot for a segment of photographers.

I gave my last Nikon F to a friend, but I still have an F2 and a Beseler 45MX. I have yearbook photography, photojournalism, studio photography, public relations photography, and event photography in my work background, plus coursework in fine arts photography from U. Florida.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 20 2012,08:33   

I looked back at my original post and see nothing controversial or argumentative.

All I said was for folks using autoexposure cameras, the difference between nominal and actual f-stop is inconsequential.

If I select 4.5 (aperture priority), the camera may select a shutter speed somewhere between 1/250 and 1/500. Actually it records the shutter speed in decimal seconds.

If I use shutter priority, the camera uses continuously variable aperture settings.

So It doesn't care what the actual transmission factor might be.

--------------
”let’s not make a joke of ourselves.”

Pat Robertson

  
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 20 2012,11:52   

Since modern cameras measure exposure based on the light coming out of the ass end of the lens into the camera box, the exposure is based on the T-stop, not the F-stop, so stop your arguing, please.  Yes, if you're using an external meter and if your lens' T-stop differs from the F-stop by an easily measureable amount and if you're shooting something like Velvia with 5-stop latitude you'll want to take this into consideration.  Shooting digital RAW with the 14 stop latitude typical of modern DSLRs (at least my canon ones) ... not so much.

One problem the movie industry faces when shooting film is that prints distributed to theaters are literally contact prints of the negative the movie's shot on.  Contact printing and bazillions of frames means there's no cost effective way to fix exposure errors, even minor ones, after the movie's shot.

The ability to manipulate the image in the darkroom while printing makes things flexible enough that still shooters have always been able to use F-stops.  Adams may've talked about T-stops in The Zone System, I don't remember, but if he did, the whole exposure/film developer selection+time/development/paper selection/manipulaton during printing/paper developer selection+time dwarfed it like godzilla stomping bambi.

  
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 20 2012,12:04   

Carlsonjok:

 
Quote
It was a bit of a cheat.  The ominous feeling of the final product really wasn't there at the start.


Well ... check out the straight and final versions of Ansel Adams' Moonrise by chasing this link:

Check it out

So easy to do in the modern digital age ... so unbelievably difficult in the era of film and darkroom.

  
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 20 2012,19:50   

It is my impression that most major movies not are edited and corrected digitally.

I use the word corrected rather loosely, since the usual correction is to desaturate some portion of the spectrum for atmosphere. The most blatant example was O Brother Where Art Thou, which dropped out nearly all green.

I believe Spielberg liked to handle film, but since movies have to be released digitally anyway, I suspect they are edited digitally, with some final prints going back to film.

That's my suspicion. I'd be interested in knowing if it's true.

--------------
”let’s not make a joke of ourselves.”

Pat Robertson

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 20 2012,23:49   

Quote (midwifetoad @ April 20 2012,08:33)
I looked back at my original post and see nothing controversial or argumentative.

All I said was for folks using autoexposure cameras, the difference between nominal and actual f-stop is inconsequential.

If I select 4.5 (aperture priority), the camera may select a shutter speed somewhere between 1/250 and 1/500. Actually it records the shutter speed in decimal seconds.

If I use shutter priority, the camera uses continuously variable aperture settings.

So It doesn't care what the actual transmission factor might be.

Thom Hogan is an expert on the Nikon system. From a review of the Nikkor 200-400mm lens:

 
Quote

Before I call out individual attributes, there's one thing I should mention: this lens is not f/4. Let me correct that: this lens is not t/4. (A t-stop is the actual transmitted light, an f-stop is the theoretical light transmission.) Actual performance is somewhere around t/5. This is somewhat normal for a zoom lens with complex optics (each air/glass surface is less than perfect in transmitting light), but it's going to be a real issue for many users of this lens. This is one of the reasons why teleconverters aren't a great choice on this lens. Even with a TC-14E the lens is approaching t/8, which is outside Nikon's AF specs.


You may not care about differences between nominal and actual light transmission. A lot of hobbyists with autoexposure equipment may not care. Other people do. That would include people who want to expose according to incident light rather than reflected light measures, or who want to choose a lens with the absolute best performance under difficult low-light conditions (something that isn't changed whether you use TTL metering or not). I'm assuming that it would also include people who want to understand the physics behind the equipment. I think my hackles got raised with the "irrelevant" phrasing in your original comment and the fact that you did at that point include autofocus in your response, and that was plainly incorrect.


Dhogaza, nobody here has at any time disputed the ability of TTL metering systems to adjust for individual light transmission differences. I'm going to have to disagree with a claim of yours. Using a film like Kodak Technical Pan developed for continuous tone (POTA, 15 minutes at 68 degrees F, no push, no pull, no nothing) that has essentially no shoulder in the highlights makes a transmission difference like the one in the lens mentioned above highly relevant and not something that would be swamped by other parts of the process. If you are using TTL autoexposure, that will (mostly) work out, but if you aren't, it will make an actual difference in your results if it isn't accounted for. I feel like I've fallen through the rabbit hole to a place where people who I know to value knowledge in other circumstances are suddenly arguing for the primacy of ignorance in this one.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 21 2012,07:11   

Well we could always convert this into an argument about gnu atheism, but seriously, my comment had a very limited scope. I had no idea I was disagreeing with anything you said.

If you are reviewing lenses on the basis of transmission, you would be lenses of the same type, as in different brands and models.

Incident light metering is rather specialized. It's used in studios and in movie making, but I think anyone going to that kind of trouble would calibrate a system with actual test shots.

Back when shutters were mechanical and involved a moving slit of varying width, it was widely recognized that effective shutter speed didn't necessarily match nominal speed.

And if you developed your own film you noticed differences between brands and types of developer. I read, for example, that National Geographic had all of their film processed in one plant, and did not allow it to be done as the first batch of the day. They wanted assurance that the chemistry was right.

For 99.9 percent of people using digital cameras, these issues are irrelevant, even if interesting. I would bet not many people shooting RAW images would notice half an f-stop difference in exposure. In fact people routinely adjust the levels in their photos to make them "pop."

This can easily truncate several f-stops of shadow and highlight detail.

--------------
”let’s not make a joke of ourselves.”

Pat Robertson

  
Schroedinger's Dog



Posts: 1691
Joined: Jan. 2009

(Permalink) Posted: April 21 2012,08:30   

So.... are we having our Lensesgate now?

Ok, ok, just kidding!

--------------
"Hail is made out of water? Are you really that stupid?" Joe G

"I have a better suggestion, Kris. How about a game of hide and go fuck yourself instead." Louis

"The reason people use a crucifix against vampires is that vampires are allergic to bullshit" Richard Pryor

   
Badger3k



Posts: 861
Joined: Mar. 2008

(Permalink) Posted: April 21 2012,09:51   

Quote (Schroedinger's Dog @ April 21 2012,08:30)
So.... are we having our Lensesgate now?

Ok, ok, just kidding!

If we are, I want a rangefinder before I friend everybody on Facebook and then defriend them.

Of course, I'm not sure what rangefinder would be useful with a Kodak easy share 1275....  :p

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"Just think if every species had a different genetic code We would have to eat other humans to survive.." : Joe G

  
socle



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Joined: July 2009

(Permalink) Posted: April 21 2012,09:52   

Quote (Schroedinger's Dog @ April 21 2012,08:30)
So.... are we having our Lensesgate now?

Ok, ok, just kidding!


  
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 21 2012,13:15   

Quote
Using a film like Kodak Technical Pan developed for continuous tone (POTA, 15 minutes at 68 degrees F, no push, no pull, no nothing) that has essentially no shoulder in the highlights makes a transmission difference like the one in the lens mentioned above highly relevant and not something that would be swamped by other parts of the process.


Well, I already pointed out that for film with limited latitude such as Velvia (slide film for those of you who don't know film from artificial cheese food) the difference between a lens' F- and T-stop could be important if they varied significantly.

Tech-Pan (which I enjoyed playing with back in the day) is certainly an unforgiving negative film.  I won't disagree with that.

Indeed, I'd say it's an exception that supports my general point that shooting typical B&W negative film, with its generous exposure latitude, coupled with the freedom one has in the darkroom with developers, paper, etc, makes a 1/2 stop difference in T- and F-stop unimportant.

After all, it is this flexibility that gave rise to the Zone System, which is end-to-end (film choice, exposure, development, paper choice, manipulation while printing, paper development, etc).

Quote
I feel like I've fallen through the rabbit hole to a place where people who I know to value knowledge in other circumstances are suddenly arguing for the primacy of ignorance in this one.


Be careful with that given your response to midwifetoad's point:

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If I select 4.5 (aperture priority), the camera may select a shutter speed somewhere between 1/250 and 1/500. Actually it records the shutter speed in decimal seconds.

If I use shutter priority, the camera uses continuously variable aperture settings.

So It doesn't care what the actual transmission factor might be.


It doesn't care in these auto-exposure modes because it's measuring through-the-lens, it just sees light.  The T-stop will always be less than the F-stop, TTL metering accounts for that.  Slap a 1-stop ND filter on the front, you'll still get a proper exposure.

You don't need to know that the T-stop of your Nikkor 200-400/4 is really closer to F-5, TTL measures the light entering the camera box, it's already taken care of.

You don't even have to worry about the fact that it's very unlikely that the 200-400/4 has an absolutely constant aperture throughout its range but probably varies +/- 5% or so.

Midwifetoad's pointing this out doesn't make midwifetoad ignorant.  Your pointing out the 1/2 stop difference between T- and F-stop in the Nikkor 200-400 just underlies the convenience of TTL metering as described by midwifetoad.

My pointing out that still shooters largely ignore the difference between T-stop and F-stop for a variety of reasons doesn't make me (or the vast majority of professional shooters) ignorant.  My pointing out that T-stop  vs. F-stop is important in traditional cinematography largely because traditionally prints were contact printed from the film negative with no opportunity for frame-by-frame (or scene-by-scene) corrections of exposure doesn't make me ignorant.

Pay attention before accusing me or others of "arguing for the primacy of ignorance".

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 21 2012,14:08   

Quote (midwifetoad @ April 21 2012,07:11)
Well we could always convert this into an argument about gnu atheism, but seriously, my comment had a very limited scope. I had no idea I was disagreeing with anything you said.

If you are reviewing lenses on the basis of transmission, you would be lenses of the same type, as in different brands and models.

Incident light metering is rather specialized. It's used in studios and in movie making, but I think anyone going to that kind of trouble would calibrate a system with actual test shots.

Back when shutters were mechanical and involved a moving slit of varying width, it was widely recognized that effective shutter speed didn't necessarily match nominal speed.

And if you developed your own film you noticed differences between brands and types of developer. I read, for example, that National Geographic had all of their film processed in one plant, and did not allow it to be done as the first batch of the day. They wanted assurance that the chemistry was right.

For 99.9 percent of people using digital cameras, these issues are irrelevant, even if interesting. I would bet not many people shooting RAW images would notice half an f-stop difference in exposure. In fact people routinely adjust the levels in their photos to make them "pop."

This can easily truncate several f-stops of shadow and highlight detail.

I think I'm getting to where I understand how my experience of your comment differed so completely from how you perceived your comment. At least part of the utility of the concept of f-stops is universality, a metric that applies to all lenses and light-passing gizmos. It allows comparison. Your comment, though, with the "irrelevant" phrasing looked to me that it simply assumed that comparison itself was not an issue of interest, and only use of a specific lens with a specific camera feature mattered.

That other parts of a photographic system have slop in them is not a reason to bypass understanding of one particular part. Nor do I find polling useful in determining whether to pay attention to and learn a technical topic. Most people don't have a clue about genetics and no demographically broad practical need to know more; should we discourage learning about the technical details as "irrelevant" there?

Let's look at what you say about comparison here:

 
Quote

If you are reviewing lenses on the basis of transmission, you would be lenses of the same type, as in different brands and models.


This is, again, much too glib.

One can easily have a comparison among multiple lenses in the same brand. Nikon makes and has made quite a variety of 85mm short telephoto lenses. The second link from my last message shows an example of a run of Nikkor 85mm lenses whose multi-coating is particularly ineffective. If one buys lenses used, knowing about this difference could result in one buying a better, higher-transmission lens from later in production. That would be a case of same brand, same model, and same marked f-stop. Or choosing which particular 85mm model to buy could involve a tradeoff between the actual light-transmitting characteristics and one's pocket-book. This isn't a simple function of adding a constant to the f-stop of all the choices.

Nor does the restriction of "same type" necessarily hold. One might choose between a zoom lens and a prime lens for a job based on light transmission. Whether one makes that decision might well be influenced by whether the circumstances permit the difference in T-stops between the two rather than f-stops. For concert photography, an additional T-stop difference as opposed to the marked f-stop difference might well tip the balance in favor of the prime lens, where the marked f-stop difference might have been an acceptable tradeoff for the convenience of the zoom, but the T-stop difference would not be.

Of course, f-stop versus T-stop is just one of many factors that would go into a lens purchase or use decision, but given the hard constraints of available light photography, it is one that will continue to engage -- and reward -- photographers looking for the very best results.

Automatic systems help produce passable results for lots of people. The Kodak Brownie camera was a huge hit in the late 1800s because it allowed people to use photography without all that difficult mucking about with picking exposure times and such-like. The fact that Brownie technology existed did not obviate the knowledge garnered by people who chose to keep on with their view cameras and glass plates. Nor do the very much improved automatic systems of today render knowledge of systems under physical constraints "irrelevant". If you only have one lens (or one lens per activity) and you simply rely on automation, conceptually it doesn't make much difference whether the camera you use is called a "Canon 5D MkII", "Nikon D700", "Holga", or "Kodak Brownie".

It's a difference between knowing your tools and "Whatever". A lot of people can (and do) get by with "Whatever", but anyone who has come away with a blurry mess where they had visualized a sharp decisive moment may well want to reconsider adherence to "Whatever" as a photographic learning strategy.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
fnxtr



Posts: 2163
Joined: June 2006

(Permalink) Posted: April 21 2012,14:43   

Barkingside!

Oh, wait, this isn't the MC thread?

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"But it's disturbing to think someone actually thinks creationism -- having put it's hand on the hot stove every day for the last 400 years -- will get a different result tomorrow." -- midwifetoad

  
Wesley R. Elsberry



Posts: 4526
Joined: May 2002

(Permalink) Posted: April 21 2012,15:00   

Dhogaza, Speaking of paying attention, I explicitly stated that no one here had at any time denied the ability of an autoexposure system to do its job. Acting as though that were a live issue isn't productive.

Nor have I accused midwifetoad or you of being ignorant of the f-stop versus T-stop distinction (or how automation functions, for that matter). What I'm objecting to is what looks to me to be encouraging others who may not know it from even considering learning about it. And I realize that that may simply be an unintended consequence of a particular word choice in that original comment by midwifetoad that has cascaded. But there have been errors committed as well, what with the mention of autofocus as not being affected by T-stop issues and the spurious restriction on how broadly comparison might be touched by that issue. The same tendency to correct invalid claims about evolutionary theory underlies my drive to correct what I perceive to be problems in claims about other topics I know something about.

And that brings us to the Zone System. The Zone System works by systematically removing the uncertainty from the equipment and processes going from film to print. There is a lot of flexibility inherent in that, but the Zone System relies upon calibration so that each element of flexibility becomes characterized and the response to perturbation can be utilized under the control of the photographer. That includes the actual light transmission characteristic of any lens used. The Zone System does not make a difference between marked and actual transmission unimportant, it makes it well-characterized and part of the control of the process that is the photographer's responsibility.

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"You can't teach an old dogma new tricks." - Dorothy Parker

    
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 22 2012,23:16   

[QUOTE]Dhogaza, Speaking of paying attention, I explicitly stated that no one here had at any time denied the ability of an autoexposure system to do its job. Acting as though that were a live issue isn't productive.[/QUOTE>

Earlier:

Quote
If you are using TTL autoexposure, that will (mostly) work out


That little word "mostly" indicates that you *can't* depend on TTL to measure T-stop vs. F-stop.  You explicitly state that it can't always do its job regarding differentiating F-stop from T-stop.


"(mostly)" is semantically equivalent to "not always".

Which is bullshit.

Now one can argue whether or not in-camera exposure systems can be as accurate is external metering systems, but that was not your argument.  But what ever errors internal metering systems make, they are based on T-stops, not F-stops, and the difference does not contribute to the error.

We could, of course, talk about the very many external incident meters that were produced in the 1930s, 40s, 50s, 60s that were such crap that their crappness swamped any difference between F-stop and T-stop or film speed or whatever.

Continue to box yourself in, I'm enjoying this.

  
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 22 2012,23:22   

Quote
Nor have I accused midwifetoad or you of being ignorant of the f-stop versus T-stop distinction (or how automation functions, for that matter). What I'm objecting to is what looks to me to be encouraging others who may not know it from even considering learning about it.


If this is truly your intent, rather than insulting someone who knows at least as much about photography as you, well ...

You're still wrong.

Modern digital photography combined with modern lenses combined with TTL exposure means you can, and should, ignore T-stop differences from F-stops.

With the 14-stop latitude modern digital cameras yield compared to the 7-stop latitude (more or less) offered by various printing technologies, you can just fucking forget 1/2 stop T-stop vs. F-stop differences, even if you meter externally.

And with modern digital cameras, internal metering is just fine.

Look, it was hard for me to trust my meter when I switched to digital and started to realize I could squeeze 14-stop latitude out of an exposure vs. the 5.5-stop or so out of chrome.

Because I realized I didn't have to be as anal about exposure as I was before (and look, I was *good* at it, selling chrome to magazines and book publishers world-wide as a side-line).

Kinda made me feel that those skills I learned were ... unimportant.

But underneath, I understood that the power of compositon, lighting, timing etc were what's really important, and if I don't need to agonize over Tech Pan's unforgiving shoulder ... that's a blessing.

  
dhogaza



Posts: 525
Joined: Feb. 2006

(Permalink) Posted: April 22 2012,23:30   

<blockquote>The Zone System does not make a difference between marked and actual transmission unimportant, it makes it well-characterized and part of the control of the process that is the photographer's responsibility.</blockquote>

It makes it very much unimportant as straight-print vs. highly-manipulated prints of Adams' photographs (such as that posted by me for "moonlight") make clear.

Crap, dude, the spring-loaded (vs. electronically timed of today) shutters were relatively flakey.

Not to mention the relatively primitive meters Adams used.

You can see from the before and after prints of "Moonlight" that Adams killed most of the dynamic range in the negative.

His T-stop vs. F-stop could've been 2 or 3 stops and he could've come up with a nearly identical image.

And, yes, I'm one of those who does not believe AA was god.

  
Lou FCD



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Joined: Jan. 2006

(Permalink) Posted: April 23 2012,06:18   

Questions into the wind:

How much post-processing (Photoshop, for instance) is too much? Where do you draw the line (if you do)?

I don't mind softening the focus a bit to play down a few years' worth of age, or zapping an unfortunate pimple, but I won't use something like liquefy to slim a hip, for instance. It's probably a completely arbitrary and subjective line, but it's mine, damnit. What's yours?

What software do you like, and why?

I'm using Digital Photo Professional (comes standard with a Canon) to sort through and do mass deletions, and maybe take a quick peek at the shots. I like the interface for selecting a group of shots, looking at them in the edit window to decide which I'm going to keep, and deleting the rest.

But for the actual post-processing, I'm using Lightroom 3. I like the controls and the end-product, but sometimes I look at some really great photographers' work and wonder if I'm missing some critical piece of software, or if its just a matter of experience.

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Lou FCD is still in school, so we should only count him as a baby biologist. -carlsonjok -deprecated
I think I might love you. Don't tell Deadman -Wolfhound

Work-friendly photography
NSFW photography

   
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 23 2012,06:32   

Must be pollen or something making people edgy on the net this week.

I have no interest in fighting over misunderstandings of intended meaning.

I would like to add, though, the observation that when i look at the levels in my digital photos, most do not use the full dynamic range. I wind up effectively bumping up the contrast.

Thi is especially true when shooting RAW, where the tools allow you to adjust the dynamics without losing highlight and shadow detail.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
Freddie



Posts: 366
Joined: Oct. 2009

(Permalink) Posted: April 23 2012,08:56   

Quote (Lou FCD @ April 23 2012,06:18)
Questions into the wind:

How much post-processing (Photoshop, for instance) is too much? Where do you draw the line (if you do)?

I don't mind softening the focus a bit to play down a few years' worth of age, or zapping an unfortunate pimple, but I won't use something like liquefy to slim a hip, for instance. It's probably a completely arbitrary and subjective line, but it's mine, damnit. What's yours?

What software do you like, and why?

I'm using Digital Photo Professional (comes standard with a Canon) to sort through and do mass deletions, and maybe take a quick peek at the shots. I like the interface for selecting a group of shots, looking at them in the edit window to decide which I'm going to keep, and deleting the rest.

But for the actual post-processing, I'm using Lightroom 3. I like the controls and the end-product, but sometimes I look at some really great photographers' work and wonder if I'm missing some critical piece of software, or if its just a matter of experience.

That's a good question.

I shoot RAW + Fine JPG, then dump them all onto the PC and decide which images to keep by looking at the JPGs in Windows Photo Gallery.  I find I can weed out the poorer images more quickly this way: delete the JPGs then go through and delete the RAWs that have no corresponding JPG in the folder.

Then I use Photoshop Camera RAW v6 for lens correction, straightening and cropping, then open up the resulting image in PS CS5 for editing (I know you can do a lot more in Camera Raw as well but I'm more familiar with CS5 having used Photoshop for about 10 years now).  

Using Camera Raw as input to Photoshop I think provides a better result than DPP --> Photoshop, as DPP can only save to JPG whereas Camera Raw uses TIFF as the intermediate file format (and Photoshop cannot open DPP files directly).

I'll usually do no more than sharpen, colour correct and adjust the dynamic range on the image using the unsharp mask, Curves tool and layer blending respectively, although I have been known to clone out the odd pimple here and there if it's only a 'temporary' feature (or clone out a bird from an otherwise flawless sky or similar etc.)  I don't think i'd ever want to materially change an image such that it doesn't represent what I actually shot but I have no qualms about using Photoshop to realize different versions of the same image.

More recently, i've been using the Shadows/Highlights tool in CS5 instead of layer blending. It can provide some fantastic results for images that have difficult exposures (or just poor ones like this off-the-cuff shot I took in Rome last week).

One item I would like to have is a better screen.  I have a 'standard' Samsung 22 inch LCD which is calibrated by eye/free tools only.  It would be nice to have a really decent screen properly calibrated for this type of work but out of my price range right now.



"Late afternoon sun at the ice cream parlour, near the Fontana di Trevi"

[ETA: Just to make it clear, the top image is the JPG off the camera, the bottom is the manipulated RAW image.  If there was no RAW I would have been stuck trying to fix the overexposed JPG which is never easy!]

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Joe: Most criticisims of ID stem from ignorance and jealousy.
Joe: As for the authors of the books in the Bible, well the OT was authored by Moses and the NT was authored by various people.
Byers: The eskimo would not need hairy hair growth as hair, I say, is for keeping people dry. Not warm.

  
midwifetoad



Posts: 3607
Joined: Mar. 2008

(Permalink) Posted: April 23 2012,09:50   

It's pretty amazing what you can do with highlight and shadow detail when shooting RAW.

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”let’s not make a joke of ourselves.”

Pat Robertson

  
Dr.GH



Posts: 1969
Joined: May 2002

(Permalink) Posted: April 24 2012,12:47   

Quote (Wesley R. Elsberry @ April 20 2012,05:38)
I gave my last Nikon F to a friend, but I still have an F2 and a Beseler 45MX.

I love my Beseler, and have kept it even without a darkroom for the last 15 years. (Some day I'll get another darkroom! Really.)

I also still have my old Pentax magazines, and screwmount lenses. Illford, and Fuji still make film (don't they?). Maybe they are all just door stops now.

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"Science is the horse that pulls the cart of philosophy."

L. Susskind, 2004 "SMOLIN VS. SUSSKIND: THE ANTHROPIC PRINCIPLE"

   
Dr.GH



Posts: 1969
Joined: May 2002

(Permalink) Posted: April 24 2012,12:54   

One totally off-the-cuff use I made of f-stops was using them as a buying guide for lenses. The cheaper lenses needed to be stopped way down because their glass, and crappy polishing  distorted images on the edges. The wider the aperture you could use, the better the glass- the better the lens.

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"Science is the horse that pulls the cart of philosophy."

L. Susskind, 2004 "SMOLIN VS. SUSSKIND: THE ANTHROPIC PRINCIPLE"

   
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