Richard Schleuning Of Zeiss Explains T-Stop Vs. F-Stop.

[MrStuPhil]

The f-stop of a lens is a simple ratio of the focal length / the aperture diameter. A 50mm 1.4 lens will have an aperture of 35.7mm. 50/35.7 = 1.4. Since the light is being transmitted through glass, some of the light is absorbed, and different lenses absorb different amounts. A T-stop is a measurement of the light that has passed through the lens, compensating for the light lost to the glass. Therefore, a T-stop is the exact amount of light transmitted by the lens and is uniform for all lenses

[death2man666]

hey he has my same last name ...... wonder if i can get a discount on some Zeiss glass then HAHAHA

[sm555]

@szabiakanich:

Same shutterspeed, no matter which manufacturer. But you will see slight differences in the result. f-stop tells you how big the opening is that lets the light through, t-stop tells you how much light actually strikes the film/sensor.

If you shoot photos, screw it. If you shoot film with multiple cameras you want to have matched images. Not only in exposure but also in color. The CP.2 are all colormatched. They use the same glass for the photo lenses, so they're matched as well.

[szabiakanich]

So what he says bascially is that if you take a Canon 50 f1,4 and a Nikon 50 f1,4 and mount them on the same camera (and set them to 1,4 @ ISO100) you would get different shutterspeed/exposure? Or the shutterspeed would be the same only that when you look at the photos you see a difference in exposure?!

[sm555]

@LivingForLOL:

The F-Stop number equals the focal length divided by the diameter of the entrance pupil.

Wikipedia: "The entrance pupil is the image of the physical aperture, as seen through the front of the lens. The size and location may differ from those of the physical aperture, due to magnification by the lens."

So a 50mm f/1.4 would have an entrance pupil diameter of 35.7mm.

[goforjared]

Fstop is math, Tstop takes the light loss into account.

[LivingForLOL]

How do you measure an F-stop? How does Canon and Nikon know it's a f/1.4 lens?

I really don't understand that kind of things........ :(