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

[SecureGSM]

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..

 

[joestopper]

Canon RF 15-35mm f/2.8 USM L IS - Review / Test Report

Canon RF 15-35mm f/2.8 USM L IS - Review / Test Report

www.opticallimits.com

Superb image quality, extreme vignetting.

Vignetting appears the price to pay for IS ...

 

[Chris.Chapterten]

I really hope the rumored 35mm f1.2 doesn't suffer from this level of vignetting

 

[Viggo]

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...

 

[Chris.Chapterten]

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]

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.

 

[mkamelg]

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)

 

[Viggo]

Loss of light in the frame corners in currently produced 35mm focal length lenses with autofocus.

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)

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.

 

[Chris.Chapterten]

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)

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!

 

[SecureGSM]

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.

 

[Chris.Chapterten]

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]

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

quite relaxed indeed...

 

[Viggo]

Does not correcting for vignetting improve the lens in other ways? Or do you think it is just down to a design flaw?

None of them, it’s due to extreme angles that ligh has to bend when the rear element is that close to the sensor.