Huh, "T-Stops"?

[mtbbrian]

I was chatting with a friend from work today whose photographic experience is quite a bit a longer than mine and he was telling me about "t-stops".
Basically a lens that has "T-Stops" rather than F Stops in theory at least, is more likely to offer a better exposure, because, " In practice, even the best lenses exhibit light absorbance, effectively “stealing” some of the light going through them. This means that if you calculate the exposure based on the f-stop of the lens, you will end up underexposing the image, because less light is reaching the film plane than is expected in theory. T-stops are the f-stop of the lens corrected for its absorbance and reflectance. The T-stop is the true speed of the lens, calculated by compensating for its light absorbance and reflectance, and will result in accurate exposure."
The above information was found HERE

Anyway, I'd love to hear what others may know and if anyone knows of any cameras that utilized "T- Stops". My friend mentioned a Canon, from many years back.
Thanks!
Brian

[Skyman]

sounds like a marketing ploy to make us buy new lenses!

[zerodog]

Dude, you don't use T stops? You are way behind the times........

Sounds interesting. More of a complete way to look at the way the light enters the camera and hits the sensor or the film? Or, just some hype.

[SmartWombat]

With TTL metering the camera is measuring transmitted light, so the idea of T stops really matters when you use an external meter.
How often do you do that?

Each lens has different transmission characteristics, depending on glass, coatings, scratches, fungus, cheap filters, dust ... what have I forgotten that affects the transmission?

I can see my old manual OM lenses have what were once considered good coatings outclassed by currentmicro 4/3 lens coatings for example.

[Grandpaw]

I'm with Paul on this! The TTL metering is reading the actual light after it goes through everything and gives you the correct exposure. To me even if you were to use a handheld meter the difference in each lens would be so small that I don't think you would see it. If you were using a handheld meter I would think that any filters that were used would make a MUCH BIGGER difference than the difference of the glass in the different lenses. Just think of all the millions of pictures taken of the years by both amateur and professional photographers that all have the wrong exposure because they did not use the T-stop method, I just don't see it. I understand that there could be a difference but I would think it would be so minimal that you could not tell the difference unless you used some type of machine or sensitive meter to read it. I just cannot believe you could see the difference if you were to take the same picture with two equal quality lenses and used the same settings, Jeff

[Greg McCary]

Could it relate to this?
FILM (ASA) SPEED TEST

[Chris350]

I'm fairly sure this as a motion picture industry standard, from when there was (maybe still is) no TTL, every thing is/was manual and hand metered. I've seen that film lenses for the industry are classed this way.

[SmartWombat]

I agree Chris, and since it's a video website I'm pretty sure that's what they meant.
I bet the Red One and other fully digital systems can measure the exposure though.

[splats]

I came into this thread thinking it was going to be about the Boston Subway AKA the "T"