21mm Summilux on M9

[rickp13]

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you're right, there is a problem finding shay stephens at the website i mentioned.

 

i used google on "shay stephens color fringe actions" and found several links and enthusiastic users, but no current address for him so far.

 

the action was only $10 when i bought it in 12/07, and worth much more in saved images. at the time there was a paypal address too:

 

paypal@shaystephens.com

 

sorry i can't help more at this time

 

greetings from hamburg

 

rick

[adan]

I have only one exposure made with a borrowed 21 f/1.4. Less severe light conditions, but I see little sign of inherent color fringing or chromatic aberration from the lens itself. See attached detail.

 

I'd suspect the main culprit in the original poster's samples is just contrasty highlights bleeding into surrounding pixels - something I can induce with any lens on any digital camera with the right, or rather, wrong, exposure.

 

For some reason, the photographic internet has decided that "Chromatic Aberration" is the appropriate term for any kind of colored edge effect that appears in photographs.

 

That is incorrect. Chromatic Aberration is a very specific (actually two very specific - lateral CA and longitudinal CA) lens fault.

 

Real lens-based CA will be visible in shots on film, and has signatures in addition to (and sometimes not even including) pink or purple fringing of bright highlights.

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[thrice]

Andy, I have a Voigtlander APO-Lanthar 180mm lens in Nikon AIS mount. This lens does not produce any kind of purple/green fringing of any kind in any lighting in any kind of exposure. I can take some improperly exposed shots to illustrate this if need be.

 

Your shot won't show any longitudinal CA because the plane of focus is right on the transition between the bright and dark areas, if you had focused on the eye it might be another story.

 

Also, purple/green/red/blue fringing etc is not sensor bloom, it *IS* chromatic aberration - a colour deviation from what was actually there (by literal definition). People need to read up on what sensor bloom is and stop making this misassociation. The OP's problem is a combination of minor lateral CA and a bit more longitudinal CA.

[ho_co]

Well, whatever you want to call it--

try different software and see if the problem is reduced.

 

I posted this kind of thing a couple times from a 21/2.8 thinking it was my M8's sensor. Then I opened the DNGs in Capture One and it was gone. It was simply the way Adobe read the file.

 

Please try doing something other than decreeing it's a lens defect and only you know the name of it and then posting something from a totally different system and saying, "Look, it isn't here."

 

What version LR are you using? With what profile?

[adan]

Daniel - well actually the plane of focus IS on the eye - just not the front one

 

In terms of judging CA, the plane of focus is the only place it can be judged, just as with resolution and contrast and so on. What happens in OOF areas is "undefined" territory - of interest to bokeh fans but not something that will be measured on the optical bench. An optical designer charged with producing an Apochromatic lens is going to work very hard to get the three primary colors to focus together in one plane, not to blur together in some other plane.

[thrice]

I bow out as we disagree as to what longitudinal chromatic aberration is. Perhaps we can have this discussion at a later time.

 

Focus is slightly behind the far eye.

 

Howard - Capture One is automatically removing/compensating-for the colour fringing, this has been covered online elsewhere if you do a quick google search, most notably RFF. PhaseOne have talked about CA corrections for Mamiya lenses in 4.1, but corrections are done for almost any lens in the later versions (4.8+) provided the nature of the CA is not too complex.

[wlaidlaw]

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If you google "purple fringing" you will find hundreds of posts and lots of opinions from both professionals and amateurs as to causes. I did quite a lot of reading up on this when I was a beta tester for Contax and one of their small but pretty expensive cameras, the titanium bodied U4R, was suffering very badly from this. The conclusion then and it would seem now, from reading various articles on the net, is that it is a combination of lens + sensor + processing + strong edge exposure + stray UV light to produce the worst examples. Kyocera, who made the sensor for the U4R, thought that CA might be occurring in the microlenses, although I personally doubt that as a cause, since each micro lens only provides photons to a single colour pixel. I think it is something we just have to accept as a fact on wide angle, non-retro focus lenses used wide open on digital RF's and process to get rid of it.

 

Wilson

[thrice]

Wilson, the Carl Zeiss 21mm C-Biogon suffers from no CA wide open. Longitudinal CA occurs in most large aperture lenses near maximum aperture, the Canon 85L - while a splendid optic - suffers noticeably from this.

If you google "purple fringing" you will find hundreds of posts and lots of opinions from both professionals and amateurs as to causes.

I will check with someone in the physics department at the university to see if I can get a published and accepted scientific journal to quote.

 

I do not think it is a factor of the sensor in any way other than the sensor reveals it moreso than film, a close to apochromatic lens produces very little colour fringing on film as well as digital.

 

I do agree that strong edge exposure makes this aberration more present, just as small point light sources near the edge of the frame make coma more apparent. The Airy disks are still distorted even if no point light sources are present to manifest the problem as coma.

 

UV light may have an influence on certain sensor/camera technologies but in a camera with a hot mirror (such as the M9) it shouldn't be an issue.

[wlaidlaw]

Wilson, the Carl Zeiss 21mm C-Biogon suffers from no CA wide open.

 

Daniel,

 

The standard 2.8 Biogon however does show CA or at least purple fringing. I have a shot taken in Barcelona Cathedral cloisters with my M8 about 3 years ago, of a fountain against the light with the 21/2.8 ZM Biogon full open. The water shower is purple. I thought at first it was light diffracting through the water droplets but on closer examination it is purple fringing. That shows that aperture is a major factor, if as you say the f4 Biogon C exhibits none of this behaviour. I had by error changed my M8 to JPEG, so I could not reprocess a DNG to eliminate it.

 

Wilson

[thrice]

The standard 2.8 Biogon however does show CA or at least purple fringing.

 

Yes, hence why I mentioned the C-biogon and not the biogon. And why I followed it up by stipulating that it's a common factor with large aperture lenses, moreso than moderate to small aperture lenses (maybe I should have clarified as such). At least we're in agreement that it's an optical phenomenon occuring within the lens.

 

Software corrections have come a long way, the "defringe" option in lightroom is pretty good, but not as good as C1.

 

If one regularly shoots high contrast bright scenes I don't understand why one would need to shoot at f/1.4 anyway. If one needs the selective focus of large aperture I guess one will just have to compose so that one's backgrounds aren't significantly brighter/darker than one's subject, or use extensive post processing.

 

EDIT: I replaced "you" with "one" so that it didn't seem I was implying these were your photographic decisions, it reads a little funny but at least it can't be misconstrued as attacking.

[thrice]

Ok, some explanation from "Optics" by E. Hecht, widely considered THE reference for optical theory and mathematics. The "axis" being referred to is the line passing directly from the source through the centre of the lens (thus not visibly refracted) to the centre of the viewing plane (eye/sensor/film).

 

"[Often] the constituent colors in a collimated beam of white light are focused at different points on the axis. The axial distance between two such focal points spanning a given frequency range (e.g., blue to red) is termed the axial (or longitudinal) chromatic aberration, A- CA for short.

 

It's an easy matter to observe chromatic aberrations, or CA, with a thick, simple converging lens. When illuminated by a polychromatic point source (a candle flame will do), the lens will cast a real image surrounded by a halo. If the plane of observation is then moved nearer the lens, the periphery of the blurred image will become tinged in orange-red. Moving it back away from the lens, beyond the best image, will cause the outlines to become tinted in blue-violet. The location of the circle of least confusion corresponds to the position where the best image will appear. Try looking directly through the lens at a source—the coloration will be far more striking."

 

It goes on to talk about compromises in optical design to compensate for different aberrations... Very heavy reading and I don't want to post too much of it because I can't be bothered typing it and because I don't want to infringe on copyright. At least now we should all understand that the purple fringing occuring behind (and depending on optical design sometimes in front of) the plane of best focus is longitudinal (axial) chromatic aberration, and that brighter intensities of light in a high contrast scene exaggerate the phenomenon.

 

The green which occurs on the opposite side of the plane of focus I assume is evidence of optical correction for colour accuracy in the plane of focus and reflects the fact that magenta and green are complimentary (magenta + green = white) wavelengths of the spectrum... I will have to read further.

[georg]

This discussion is basically about what causes this artifact - can it be resolved with a better lens design or is it caused by the sensor (+certain optical circumstances that can be found in fast lenses) and therefore has to be solved with a better sensor design!? Anyway, we can "hide" it with proper processing quite well.

 

The 21mm Summilux has CA but it's negligible in comparison to many other high-quality WA. But this specific effect (which makes the images unusable in my eyes) is not any kind of optical aberration within the lens. Why?

 

1. Just try film, you'll instantly see the difference. (thanks adan)

2. Look closely at this image Flickr Photo Download: Leica Noctilux-M 50mm f/0.95 @ f/0.95 when you look on the right you will notice that this "aberration" only appears with high-contrast and "magically disappears" elsewhere and you see that this artifact "overlays" the actual detail (the brick) - none of this would happen with "classic CA". It's even more obvious on the Summilux 21mm examples

 

I have no idea what actually causes this artifact within the camera (microlenses, oblique light rays, thick cover glass, blooming?) but it has to be clear that todays sensors are still far away from artifact-free and we shouldn't necessarly blame the lens without the comparison on film.

[thrice]

1. I shoot film primarily with both R and M glass, I'm well aware that digital sensors exaggerate the problem, indeed I mentioned it. I've also seen it in film.

2. I also explained that certain conditions make abberations more apparent (my coma reference) but perhaps you ignored that.

 

Here is a completely unremarkable shot taken with the 50mm Summilux-R E60 (a high end lens by any stretch of the imagination). It's shot on Superia 400 with the R8.

Sorry upon reviewing the picture in lightroom it appears I processed the purple fringing out, but I reverted to the original file before taking the crop.

Here is a crop...

 

You dismiss clear explanation from one of the accepted authorities in optics, offer no evidence of your own and then claim you have no idea what causes it... I'm leaving this conversation, I believe I've made my point empirically and irrefutably, if you choose to still disagree that's not my fault.

[smgorsch]

Back to the OP, who, understandably, doesn't wan't to fuss with patches & wants to shoot without too much fear of artifact. Since it appears that different processing algorithms influence the degree to which this is seen & that this was seen with LR, I might suggest that he download LR beta 3 (different engine supposedly) to determine whether the artifacts are less evident. If so, problem resolved

 

Stefan

[Googaliser]

This discussion is basically about what causes this artifact - can it be resolved with a better lens design or is it caused by the sensor (+certain optical circumstances that can be found in fast lenses) and therefore has to be solved with a better sensor design!? Anyway, we can "hide" it with proper processing quite well.

 

The 21mm Summilux has CA but it's negligible in comparison to many other high-quality WA. But this specific effect (which makes the images unusable in my eyes) is not any kind of optical aberration within the lens. Why?

 

1. Just try film, you'll instantly see the difference. (thanks adan)

2. Look closely at this image Flickr Photo Download: Leica Noctilux-M 50mm f/0.95 @ f/0.95 when you look on the right you will notice that this "aberration" only appears with high-contrast and "magically disappears" elsewhere and you see that this artifact "overlays" the actual detail (the brick) - none of this would happen with "classic CA". It's even more obvious on the Summilux 21mm examples

 

I have no idea what actually causes this artifact within the camera (microlenses, oblique light rays, thick cover glass, blooming?) but it has to be clear that todays sensors are still far away from artifact-free and we shouldn't necessarly blame the lens without the comparison on film.

 

Thanks for this. To be clear, I have no interest in blaming the lens. The lens is part of a system - and there is an issue somewhere in the interplay of the various components. The lens is the only variable, however, that I have control over - thus I think it has to go. Let me explain

 

I do a lot of available light work. I shoot my Nikon 28mm wide open at 1.4 the vast majority of times. I shot a birthday party this weekend - 300 exposures all wide open on a Summilux 50 - right on the edge of the M9's abilities - some would say over. Technically the Nikon would have done a better job (many of the shots were at ISO 1000+ and 1/10s) - but the results were worth it. People didn't see me taking the shots and thus I was able to capture the essence of the occasion.

 

Do I need a 21mm @ 1.4 - I'm not sure - but creatively it excites me. Does it excite me enough to spend £4K+ ? Yes - thats why I bought it. But I assumed I was buying a state of the art optic which interacted flawlessly with the rest of the system. Its seems this assumption itself was flawed. Thats not to take anything away from the lens - perhaps it does what it says on the tin, or that reviewers have raved about. But the practical reality is that it doesn't work me on my M9 and my chosen workflow. I expect my system to be very special when I have £4K glass on it. To have to worry about purple fringing - whatever the cause is - its something I would be prepared to do and fix on a £400 lens - but not on a £4K one. I guess 21mm 1.4 doesn't matter THAT much to me !

 

PS: I hate the fact I have to use Phocus for my Hassy files. A big selling point for me on the Leica - as silly as it sounds - was DNG and thus a Lightroom workflow as per my Nikon. To have to use C1 for Leica is just not practically something I'm prepared to do. 3 workflows for 3 systems would drive me insane.

 

 

Rgds

[Googaliser]

Back to the OP, who, understandably, doesn't wan't to fuss with patches & wants to shoot without too much fear of artifact. Since it appears that different processing algorithms influence the degree to which this is seen & that this was seen with LR, I might suggest that he download LR beta 3 (different engine supposedly) to determine whether the artifacts are less evident. If so, problem resolved

 

Stefan

 

Thanks for the suggestion. In fact, I have LR3 beta up and running on one of the computers and the issue is still prevalent. Also, the CA sliders do nothing for my sample images.

What wasn't perhaps clear on the upload JPEGS was that in many cases there was a green edge on the other side (of the object) with the purple edge - which screams CA to me.

[jonoslack]

Thanks for the suggestion. In fact, I have LR3 beta up and running on one of the computers and the issue is still prevalent. Also, the CA sliders do nothing for my sample images.

What wasn't perhaps clear on the upload JPEGS was that in many cases there was a green edge on the other side (of the object) with the purple edge - which screams CA to me.

 

Hi There

Sorry if this is a redundant suggestion (no time to read the whole thread). This has come up elsewhere, and the best solution seemed to be to use C1 to do the conversions. If you haven't got it, you could download a trial and give it a go.

[georg]

"in many cases there was a green edge on the other side (of the object) with the purple edge"

 

That sounds like "classic CA", indeed.

 

But this example in particular makes it quite clear that this a special phenomenon (you can clearly see detail underneath the pink):

http://www.l-camera-forum.com/leica-forum/attachments/leica-m9-forum/170986d1257105558-21mm-summilux-m9-f5.6.jpg

[Googaliser]

"in many cases there was a green edge on the other side (of the object) with the purple edge"

 

That sounds like "classic CA", indeed.

 

But this example in particular makes it quite clear that this a special phenomenon (you can clearly see detail underneath the pink):

http://www.l-camera-forum.com/leica-forum/attachments/leica-m9-forum/170986d1257105558-21mm-summilux-m9-f5.6.jpg

 

Here's a 100% of the Chimneys at 1.4.... Now, according to Reid, Puts et al, wide open, mild CA is to be expected. I show this example though because the purple persists through to F16, although the green fades. I would say that if you can get comfortable with this as an example of CA, then the rest of the images are also due to CA. Even at F16 !!

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Hallo,

Look here: Leica M

[wlaidlaw]

Here's a 100% of the Chimneys at 1.4.... Now, according to Reid, Puts et al, wide open, mild CA is to be expected. I show this example though because the purple persists through to F16, although the green fades. I would say that if you can get comfortable with this as an example of CA, then the rest of the images are also due to CA. Even at F16 !!

 

It would be interesting to get an opinion from Leica, if you sent them the above shot. Now we all know that there is a degree of variance amongst Leica lenses, to the extent there are dogs and gems at the opposite ends of the spectrum. I have one of each and the rest are just good. It might be that your 21/1.4 is at the canine-ish end, in particular as far as CA is concerned. For the cost of a 21 Lux anything other than "gem" is not really acceptable.

 

Wilson