Optical Limits reviews Canon RF 15-35mm f/2.8 USM L IS

SecureGSM

2 x 5D IV
Feb 26, 2017
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860
It's pretty well inevitable with a short sensor-rear element distance that you will get heavy vignetting. The light from, for example, the extreme right of the rear element strikes the extreme left of the sensor at a very sharp angle. So you have to correct for it either electronically or physically. A flexible concave sensor would be one answer, but I think that would be rather too esoteric. These problems don't worry me as I mainly use telephotos and these have the rear elements well inside the lens. My Sony RX10IV gives excellent images despite heavy corrections for distortion and vignetting.
The Sony E 16-35/F2.8 GM is also designed for a short sensor-rear element distance. and "only" 3.5 stops of vignetting in extreme corners. Uncorrected.. so..
 
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Viggo

EOS 5D SR
Dec 13, 2010
4,441
1,105
I really hope the rumored 35mm f1.2 doesn't suffer from this level of vignetting
The RF50 has pretty severe vignetting, but only at infinity focus, so for normal distance shooting it’s just fine, the RF 85 is excellent with vignetting. So wider seems worse, so a 35 f1.2 might be pretty bad...
 
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Feb 15, 2020
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The RF50 has pretty severe vignetting, but only at infinity focus, so for normal distance shooting it’s just fine, the RF 85 is excellent with vignetting. So wider seems worse, so a 35 f1.2 might be pretty bad...
I have the RF50mm and haven't found the vignetting to be as bad as I thought it would be. I never shoot at infinity focus so that may explain things, thanks for clarifying.

If that is the case with the RF35 1.2 I wonder if it would be better to adapt the 35mm 1.4L ii instead? If they can match the vignetting of the RF50mm and not be any worse than that.. that would be fine by me... but I suppose it's looking unlikely
 

YuengLinger

EOS 5D MK IV
Dec 20, 2012
2,860
1,102
Southeastern USA
I have the RF50mm and haven't found the vignetting to be as bad as I thought it would be. I never shoot at infinity focus so that may explain things, thanks for clarifying.

If that is the case with the RF35 1.2 I wonder if it would be better to adapt the 35mm 1.4L ii instead? If they can match the vignetting of the RF50mm and not be any worse than that.. that would be fine by me... but I suppose it's looking unlikely
The ef 35mm 1.4L II works and balances beautifully on the R.
 
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mkamelg

I'm New Here
Feb 1, 2015
23
10
Poland
The RF50 has pretty severe vignetting, but only at infinity focus, so for normal distance shooting it’s just fine, the RF 85 is excellent with vignetting. So wider seems worse, so a 35 f1.2 might be pretty bad...
Loss of light in the frame corners in currently produced 35mm focal length lenses with autofocus, with aperture values f/1.2 and f/1.4.

Sigma Art 35mm f/1.2 DG DN Sony FE mount: 73% (−3.76 EV)

Sigma Art 35mm f/1.4 DG HSM Canon EF mount: 66% (−3.16 EV)

Tamron SP 35mm f/1.4 Di USD Canon EF mount: 66% (−3.13 EV)

Canon EF 35mm f/1.4L II USM: 64% (−2.95 EV)
 
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Viggo

EOS 5D SR
Dec 13, 2010
4,441
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Non of these are made for very short flange distance like the RF mount, so seeing the 1,4 mk II at three stops, I suspect a 1.2 RF version will have 5 stops, at least, which is just ridiculous.
 
Feb 15, 2020
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Very useful information, thanks for posting. If the RF 35mm really does have 5 stops of vignetting it definitely looks like an adapted 35mm 1.4L ii is the way to go!

Edit: just had a look at the RF 35mm 1.8 and that lens has 3.8 stops of vignetting at f1.8. What are the chances of the L version being better than that? I really hope it is!
 
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SecureGSM

2 x 5D IV
Feb 26, 2017
1,928
860
Non of these are made for very short flange distance like the RF mount, so seeing the 1,4 mk II at three stops, I suspect a 1.2 RF version will have 5 stops, at least, which is just ridiculous.
The Sigma 35/1.2 DN is a Sony E mount lens. designed for a short flange distance with 3.76 stop of vignetting in extreme corners. However, it seems that Canon engineers being quite relaxed about their vignetting levels on RF mount.
 
Feb 15, 2020
89
72
The Sigma 35/1.2 DN is a Sony E mount lens. designed for a short flange distance with 3.76 stop of vignetting in extreme corners. However, it seems that Canon engineers being quite relaxed about their vignetting levels on RF mount.
Does not correcting for vignetting improve the lens in other ways? Or do you think it is just down to a design flaw?
 

Viggo

EOS 5D SR
Dec 13, 2010
4,441
1,105
The Sigma 35/1.2 DN is a Sony E mount lens. designed for a short flange distance with 3.76 stop of vignetting in extreme corners. However, it seems that Canon engineers being quite relaxed about their vignetting levels on RF mount.
Thanks, I missed the one (y)

quite relaxed indeed...