T-Stop of Canon 70-200mm f/2.8L IS?

[Roberto Lequeux]

Does anyone know the T-Stop of the 70-200mm?

I suppose it might ramp a bit as well so if anyone knows detailed info it would be nice to know, or even just an approximated overall T-stop would be useful.

Thanks

 

[Alexander Ibrahim]

Well, my limited tests indicate a T/2.9 without appreciable ramping.

There is some ramping, if you do some serious pixel peeping, but I consider it negligible under most real world circumstances.

What I always advise is that you do your own testing. Establish your notion of the camera's baseline ISO with a known true lens. (I used a Zeiss Ultra Prime 50mm) Once you are satisfied you understand the RED's exposure index, then start goofing with other lenses.

If hiring lenses near you is difficult, then definitely buy in at least one of the Zeiss Compact Primes, the Cooke Panchros or an RPP. Use that as your baseline for evaluating other lenses.