new Red primes

[jbeale]

Looking at the 5-lens Red Prime set at http://www.red.com/lenses.shtml I am wondering about f-stops vs T-stops. The lenses are listed at f2.8 and f1.9 but I thought cine lenses are typically rated using T stops. My understanding is that f-stops are theoretical and T-stops are based on actual measurements. Can anyone comment on the difference, if any, in this case?

[Policar]

I'd assuming they're about t3 and t2, respectively, but I don't know for sure.

In fact, the primes (except the 15mm) seem oddly like Cooke S4s...

Hopefully.

[Anders Holck]

Yes:
F stops.
Theoretical ratio based on the Focal lenght divided by the diameter of the aperture. This value gives a hint about the lens speed, but more importantly this value dictates the DOF.

T stops.
The actual light transmission.

It is most common to use T stops on film lenses, as you tend to measure exposure by using an incident light meter and not TTL like a SLR or a video camera.

[Stephen Williams]

I'd assuming they're about t3 and t2, respectively, but I don't know for sure.

In fact, the primes (except the 15mm) seem oddly like Cooke S4s...

Hopefully.

Hi,

They need to be measured, no point in guessing.

Stephen

[Policar]

Hi,

They need to be measured, no point in guessing.

Stephen


Actually, no. It's a video camera, so there's no need to measure, although obviously a guess is just a guess.

And I was only guessing since rumors indicate the lenses are made by (or designed by) Cooke...which is known for its t2 primes and t3 zooms.

[chuck colburn]

f stops are properly called a geometric apreture. And as Anders said is the focal length divided by the diameter of the iris and are used to calculate depth of field.

[Stephen Williams]

Actually, no. It's a video camera, so there's no need to measure, although obviously a guess is just a guess.

And I was only guessing since rumors indicate the lenses are made by (or designed by) Cooke...which is known for its t2 primes and t3 zooms.

Hi,

When you change lens, using an identical T stop will be benificial. As some users of video cameras aren't very bothered about matching scenes, you may well be right.

Stephen

[Damien Molineaux]

Hi,

When you change lens, using an identical T stop will be benificial. As some users of video cameras aren't very bothered about matching scenes, you may well be right.

Stephen

Stephen, you have a way with words... makes things very clear. They say a picture is worth a thousands words. With your capacity to clarify things in so few words, I can only guess what your images express... I would very much like to see you work and your work.

If you haven't had a chance, or want to do more tests, with a Red One; I would very much enjoy having you put my Red One through it's paces. I should be getting it in August, if delivery dates don't change.

Cheers,
Damien