Would the 35mm f/1.4L be redundant given my current glass collection?

Started May 19, 2012 | Discussions thread
Peter 13
Veteran MemberPosts: 8,301
Re: Would the 35mm f/1.4L be redundant given my current glass collection?
In reply to ultimitsu, May 19, 2012

ultimitsu wrote:

Peter 13 wrote:

BTW, the 17-55 (and just about any other lens) does not get you the advertised transmission either:


Click on Measurements, Transmission. The loss is 0.7 Ev vs. 0.5 Ev for f/1.4 lenses.

I could be wrong but I think this is a different problem. This loss seems to be caused by the number and quality of glasses in the lens, so the loss will be constant at all apertures, I.e. at 2.8 you lose 0.7, at f4.0 you still lose 0.7. Also primes all seem to only lose 0.2, I guess it is due to less number of glasses inside. 24-105 loses 1.1 stop and 16-35 loses o.4 stop.

Basically you have pile this loss on top of the micro lens loss, so for 1.4 lens it will be 0.2 + 0.4 = 0.6 stop loss at f 1.4.

They are not very clear about this. My understanding is that they measure the total loss wide open regardless of what causes it. The primes are brighter but wide open you have microlens vignetting - so there is some balance of the two factors. In terms of "QE", I still believe that 0.7-0.5-0.2 is right.

I have done experiments with my 35L on the 5D2. I can measure 0.2 EV with LR4. DXO says about 0.4 or so. This only makes sense if the DXO figure includes light loss due to glass and Canon not telling the whole truth plus about 0.2 microlens vignetting.

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