Joined: Feb. 2006
|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).
|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:
|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".