Canon RF 85mm f/1.2L USM coming May 9, 2019

MayaTlab

EOS 80D
Oct 6, 2015
191
77
You could be worried...or you could learn to appreciate cat’s eyes... :p
The problem with the 50 isn't the nature of the vignetting, which is unavoidable, but its degree. Just like the 50L it's got so much of it that you're not getting f1.2 worth of DOF for most of the frame. In practice you're rather getting the DOF of a 50mm f1.4 lens that's well corrected for vignetting. I guess that this is just the result of the compromises that had to be made between marketing asking for a f1.2 lens that's sharp and a small size. IMO the 50 RF would have been a better tool had it been designed as a f1.4 from the start and nearly no one would have seen the difference in pictures.

It's totally the smart thing to do as they can sell it for €2500 euros and can introduce the RF mount with a fanfare but it's not really what serves the users the most IMO. I think that a 50mm f1.4 with low vignetting and zero astigmatism would have made for a more significant difference over previous designs.

Anyway I'm quite excited to see which design choices Canon will make with this new 85mm and how they'll implement the apodization exactly. For starters that it's a coating technology is quite something as Canon claims they could more easily implement apodization in various designs.
 

SwissFrank

EOS RP
Dec 9, 2018
301
116
Also, the apodized lenses we're seen so far tend to quickly loose their blur qualities as the lens is stopped down.
What I'd love is a slot to stick in your own filter, and have a suite of filters with transmissions of say T/2, T/2.8, T/4, etc. Even for a given T there are infinite different gradations you could use giving different highlight shapes. There's no one best answer.
 

MayaTlab

EOS 80D
Oct 6, 2015
191
77
There's no one best answer.
Agreed. I'm super curious to see how Canon's approach to engineering apodization, ie a coating, not an internal filter, will affect the results. Perhaps they'll be able to implement a more progressive gradient than the Sony STF which should help when closed down.
 

Bob Howland

EOS 7D MK II
Mar 25, 2012
443
46
I think it’s utter cr@p that great lens lenses are somehow a waste on lesser bodies... it’s not even close to be true..

Would I rather have the 200 f2 on the RP or an old 75-300 on a 1dx2? Easy...
I'd rather have the 24-240 on the RP than the 200f/2.
 

SwissFrank

EOS RP
Dec 9, 2018
301
116
The problem with the 50 isn't the nature of the vignetting, which is unavoidable, but its degree. Just like the 50L it's got so much of it that you're not getting f1.2 worth of DOF for most of the frame. In practice you're rather getting the DOF of a 50mm f1.4 lens that's well corrected for vignetting. I guess that this is just the result of the compromises that had to be made between marketing asking for a f1.2 lens that's sharp and a small size. IMO the 50 RF would have been a better tool had it been designed as a f1.4 from the start and nearly no one would have seen the difference in pictures.
Think of a 50/2. The highlights aren't circular, and that's because they're running into the sides of the lens elements (to massively oversimplify). Where that "entrance pupil" should be visible off-center, instead you see the front element surround or the back element surround.

So make those bigger, and now some internal element is the bottleneck. Keep making things bigger until you can see the entire circle center to corner on your f/2 lens.

But by the time you're finished, what you've done is actually almost more or less made an f/1.2 lens, whose aperture is limited to f/2.

So as the last step you replace the aperture blade unit with one that can open wider, and suddenly you've got an f/1.2 lens with vignetting again, but that can deliver perfect circles at f/2.

So maybe the idea of a lens giving perfect circles wide open just won't happen, since the aperture of any lens capable of that could also simply be opened up further to the point it has the mechanical vignetting and American football-shaped highlights.

--------

Now what interests me is that the RF 50/1.2 is designed to actually be sharp as heck wide open, with practically non-existent aberrations. Great for Canon and I love them for it, but it makes the lens design complicated, heavy, and expensive.

But what if they knew the lens would be used with an apodization filter? That practically none of the light from the elements' periphery would actually be ending up on the sensor, thanks to the filter? Then suddenly correction aberrations for light coming on the edges of the elements is not at all important and you can massively simplify the design without really affecting image quality.

So, this would let you design a 135/1.4 or even 135/1.2 or 135/1, with really crap sharpness wide open due to the edges of the image circle being extremely aberrated. BUT, you stop the 135/1 down to 135/1.4 and now you have perfectly round highlight circles center to corner. (And aberrations!) Then you add the apodization filter, and almost none of that aberrated light gets through, just enough to make the bokeh circle really soft. The transmission is now T/2, even though the width of the bokeh circles is still the same as f/1.4 (to the extent you can even see the fuzzy edges' real edge).

Result is a 135/1 lens with the same front element size as a 400/2.8 or 600/4! But it's cheap glass and not thick because they don't care about aberrations in normal use. Perhaps it could be used wide open but not at all designed for that, instead it's designed to be physically f/1.4 but filtered down to T/2. In short for some subject matters it'd look like the 135/2 wide open, but if the background had points of light they'd be cotton balls not disks.
 
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SwissFrank

EOS RP
Dec 9, 2018
301
116
Perhaps they'll be able to implement a more progressive gradient than the Sony STF which should help when closed down.
I don't think there's any filter pattern you could use that would look good for multiple f-stops. Basically this filter, if you set it on a piece of white paper, will show you exactly the highlight shape you'd see, and a fuzzy circle as wide as an f/1.2 aperture simply will have sharp edges at f/1.4. You just can't get around that.

One idea I had was aperture blades that instead of hard edges had this gradient effect of the filter. Then you could resize the gradient. But I don't see how to make that work in practice. The best idea I have is just a slot to drop in the gradient filter--or take it out if you want a non-gradient lens.
 

MayaTlab

EOS 80D
Oct 6, 2015
191
77
So maybe the idea of a lens giving perfect circles wide open just won't happen, since the aperture of any lens capable of that could also simply be opened up further to the point it has the mechanical vignetting and American football-shaped highlights.
It's an intuitive way of thinking about it, but I don't have the knowledge to be quite so sure that this is exactly how it works :D.

From what I've read the difficulty in managing aberrations isn't quite "linear" with increasingly wider apertures.

Now what interests me is that the RF 50/1.2 is designed to actually be sharp as heck wide open, with practically non-existent aberrations.
It has aberrations :D. Point light sources at the periphery show more aberrations than, for example, the Sigma 40mm 1.4. Perhaps some astigmatism but I don't know how to interpret these well (it could explain what I don't like about the RF's bokeh off centre). It's also got quite a bit of CA.
I mean, it's a very well corrected lens, that's for sure. But off centre it's a bit off the truly world class mark that's all the rage these days.

But what if they knew the lens would be used with an apodization filter? That practically none of the light from the elements' periphery would actually be ending up on the sensor, thanks to the filter?
You could argue that its vignetting already helps tremendously in that regard, at least in one axis :D.

I don't think there's any filter pattern you could use that would look good for multiple f-stops.
I have no idea about apodization filters - hence why I'm curious to see how Canon will implement apodization with the 85mm DS, but it's kinda possible with undercorrected spherical aberration. This is how the Nikon 58mm behaves when shooting a very small, bright (and here, green) point light source is shot slightly in front and behind the focal plane. The gradient you see between the centre and the edge of the background blur is maintained even when the aperture is closed down. Of course that lens is a very extreme design that puts all its eggs in one basket, but it's an illustration of how it's possible to get an "apodization" like gradient, even at smaller apertures, by biasing the blur quality in favour of rear gaussian smoothness (at the detriment of front side blur, sharpness, focus shift, etc.).

184155

All the credit should go to Marianne Oelund, who initiated this thread on the subject, unfortunately now the pictures have been lost : https://www.dpreview.com/forums/thread/4031515
 

padam

EOS 7D MK II
Aug 26, 2015
599
217
I'd be very curious to know how many are selling their DSLR's and EF mount lenses for this new very expensive gear.
New gear is always very expensive (does not matter if it is a new EF lens or a new DSLR or anything that is new) and it always gets discounted as time goes on.
It just seems that it is even more costly, if one is buying a lot of it in one go. Switching to mirrorless (with native lenses) is expensive, doesn't matter which brand (or it is a compromise in sensor size, etc. etc.) and using an adapter is a viable solution as well

on the other hand all this new gear also pushes down the value of older gear, that was excellent yesterday - and is just as excellent today
 

Bob Howland

EOS 7D MK II
Mar 25, 2012
443
46
I agree, if you do not think that glass is more important than the body you have another thin[k] coming.
That was very true in the film era with manual focus cameras. Then, the camera was largely a box to hold film and a shutter and to mount lenses. It is much less true in the era of a digital sensor inside an autofocus camera body.
 

ashmadux

Art Director, Visual Artist, Freelance Photography
Jul 28, 2011
427
19
New Yawk
photography.ashworld.com
NICE....i mean, with no IBIS, and no stabalization, on a much lighter body...going to be interesting times in hit-rate land. Maybe.

"but its the technique"

Yeah, sure it is. it's also a lack of a feature. Happy shooting!
 

sanj

EOS 5D MK IV
Jan 22, 2012
3,202
74
Canon is forcing me to buy the R. I was holding on till they come out with the pro body. Aaaaaaaaa
 

slclick

PINHOLE
Dec 17, 2013
3,157
685
Canon isn't forcing me to do anything. My 2012 body works just great and my lenses from STM to L with or without IS all work great and 100% of the image quality rests with me. No copouts.
 

sanj

EOS 5D MK IV
Jan 22, 2012
3,202
74
Canon isn't forcing me to do anything. My 2012 body works just great and my lenses from STM to L with or without IS all work great and 100% of the image quality rests with me. No copouts.
All my gear got stolen. I am rebuilding my list. I shoot wildlife and video. So am waiting for a pro body. And thanks for the reply.
 
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neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,610
2,072
NICE....i mean, with no IBIS, and no stabalization, on a much lighter body...going to be interesting times in hit-rate land. Maybe.

"but its the technique"

Yeah, sure it is. it's also a lack of a feature. Happy shooting!
I’m so sorry your camera can’t achieve a shutter speed of 1/100 s or faster. Mine can, so I’ll be just fine. Or I’ll use my 85/1.4L IS with the adapter. Choice is good. You’re choosing to petulantly whine. Good for you.
 

mb66energy

EOS 6D MK II
Dec 18, 2011
1,288
193
Germany
www.MichaelBockhorst.de
What I'd love is a slot to stick in your own filter, and have a suite of filters with transmissions of say T/2, T/2.8, T/4, etc. Even for a given T there are infinite different gradations you could use giving different highlight shapes. There's no one best answer.
... or something like a transparent (LCD) display in the lens with high resolution which creates the apodization pattern :) Some menu item where you can draw you own apodization pattern in-camera.

But major drawbacks are that it is polarizing (sometimes helpful, always loosing ~1 stop of light) and I am not shure if it is possible to make optically "clear" displays with very uniform transmission and at least 128 precise gray levels ...

EDIT: Forgotten to say that there are some revived lens designs where the f-stop is chosen by f-stop-slots like the petzval from lomo: https://shop.lomography.com/en/petzval-85-artlens-canon?country=de -- make your own filters via 3D printing or / and painting with a gray marker on glass ...
EDITEDIT: Lomo thought about customization: right item of https://shop.lomography.com/en/petzval-special-aperture-blades
 
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