Canon 24-105 more light loss than expected

[Lenilenapi]

I just got a Canon f4 AF IS L zoom and am finding to my chagrin that f4 on this lens is nearly a stop darker than on any of my other lenses. Thus I'm sacrificing 2 stops instead of the expected one for the additional reach.
Can any one else verify this or is something wrong with my lens?

Lenny Levy

 

[TimurCivan]

its darker on the long end....

 

[ROCKMORE]

I just got a Canon f4 AF IS L zoom and am finding to my chagrin that f4 on this lens is nearly a stop darker than on any of my other lenses. Thus I'm sacrificing 2 stops instead of the expected one for the additional reach.
Can any one else verify this or is something wrong with my lens?

Lenny Levy

What other lenses are you comparing it to?

 

[saneproductions]

Strange, it shouldn't have any iris ramping. Now you are making me want to go to work and do some tests. I really can't see it being a whole stop darker though. I would have noticed.

 

[Lenilenapi]

Went to Calumet today and compared it to a 17-55 and a prime 85. Confirms my tests at home. Its not ramping, not losing light on the long end its just flat out about a stop slower than every other lens I've tried at f4. I'd call it a T5 or T5.6. 17-55 by the way matched the prime.
I'll have to test my buddy's 70-200 f4 and see if it has the same problem.
Funny that none of the salesmen at Calumet knew it.

Lenny levy

 

[Ben_B]

That's an awesome lens

What kind of work are you doing, can you not light for t/5.6?

Also did you only look at the differences at wide open or did you test other apertures...for example is it similar to your other lenses when they're all set to f/8?

 

[Green Hornet]

I just got a Canon f4 AF IS L zoom and am finding to my chagrin that f4 on this lens is nearly a stop darker than on any of my other lenses. Thus I'm sacrificing 2 stops instead of the expected one for the additional reach.
Can any one else verify this or is something wrong with my lens?

Lenny Levy

Is their a filter on the back of the lens?