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Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"

Started Dec 9, 2013 | Discussions
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LeicaBOSS
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Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
Dec 9, 2013

Hi all. I've had the opportunity to really kick the tires on the Sony A7r / FE 35mm f/2.8 combo. It's a great lens, but WOW there's some funky color shift going on. When profiling the lens for Adobe Flat Field, I noticed a bullseye shape to the color shifts - a number of alternating neutral and magenta rings going almost to the center of the frame.

It is visible in images - particularly if you get an overcast or cloudy day and expose to the right a bit.

More here: http://www.leica-boss.com/2013/12/the-problem-with-sonys-zeiss-fe-sonnar-t-fe-35mm-f2-8-za-sel35f28z/

I don't want to dissuade anyone - it's a fantastic lens - but this effect is definitely a real thing and it's very peculiar.

  • Persists even when you stop down - but to a lesser degree
  • In-camera correction does not resolve it (neither in JPG nor when using Sony IDC)
  • Flat Field plugin WILL help or even eliminate this issue - but you really need to match the light source and aperture to the reference exposure (using an f/2.8 reference exposure on an f/8 image results in different-looking color shifts)

I hope others can contribute!

A7r + FE 35mm f/2.8 through Expodisc. RAW processed in LR5. Color enhanced to show form of aberration.

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DavieK
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

This is interesting - in some ways I wish I had not sold my Voigltander 15mm, as one issue which bothered me was a yellowish patch at the top of the frame as well as the usual magenta/purple vignetting. Now I can see that yellowish patch is present on your 35mm image.

I can't think of any reason for this other than an inherent fault in the sensor.

David

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Paul1974
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

Do you shoot all of your photo's through Expodisc? Seriously, it may be because there is no AA-filter. In lab set-ups these things are to be expected. Please attend a photo course or two and enjoy shooting real life images.

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Lightshow
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013
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Steven-T
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to Lightshow, Dec 10, 2013

Lightshow wrote:

Lets see it without the Expodisc.

That would be nice.  BTW, how accurate is the resulting CWB?

. . . Steven

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MoreorLess
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to DavieK, Dec 10, 2013

DavieK wrote:

This is interesting - in some ways I wish I had not sold my Voigltander 15mm, as one issue which bothered me was a yellowish patch at the top of the frame as well as the usual magenta/purple vignetting. Now I can see that yellowish patch is present on your 35mm image.

I can't think of any reason for this other than an inherent fault in the sensor.

David

I'm guessing the issue is the very small flange distance and a FF sensor. The RX1 copied with it but that was a fixed lens camera that did I believe have a very large rear element(larger than could fit in an E mount) that likely helped in some way.

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martindesu
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

A friend had the same results when comparing the RX1R and A7R. I'm not exactly impressed...

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Erik Magnuson
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

Hmm, wonder if the rings are zones of different offsets of the microlenses.

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Cane
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

You have to really enjoy this kind of testing, because there's no way anyone could stay awake long enough to do it, much less read about it.

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Keit ll
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to Cane, Dec 10, 2013

I agree that we need to see some images without the expodisc - this is a device for adjusting WB & is not intended for other purposes. Does it enable the correct WB or is the effect shown biasing the settings in some manner ?

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twald
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

One thing that you should try is to turn OFF all lens correction.

As earlier demonstrated with the NEX-5N, vignetting corrections are applied to raw files and the results can show up in images of high-contrast scenes. This was particularly noticeable with lenses that vignette heavily, such as the SEL16f28. It showed up as circular banding but was confined more to the periphery of the image.

If this doesn't fix it, then it is likely an unfortunate side effect of the "special offset micro lenses" Fortunately, if it can be easily fixed with special post processing software then it should be possible for Sony to fix it with firmware.

Sadly, I can't afford the A7/R nor the Zeiss FE 35mm f/2.8 , so I can't test it myself.

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stjarvis
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to twald, Dec 10, 2013

This is from my NEX 5R, I think you can see it a little here:

I haven't noticed it in any of my other shots with the lens, and didn't even catch it in this one till I went back and looked for it (slight magenta shift near the edge of the vignetting), this was taken @ 2.8.

This still might be my eyes playing tricks on me.

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twald
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to stjarvis, Dec 10, 2013

I am re-posting some 5n shots that I uploaded a long time ago. The effect is not nearly as dramatic s the A7 examples but it does demonstrate that Sony applies lens vignetting correction to raw files and that vignetting correction involves changing colors. Note the purple bands on the periphery of the first image.

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KwhyChang
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 10, 2013

Mine works fine.

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Dave

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miro3
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to KwhyChang, Dec 11, 2013

KwhyChang wrote:

Mine works fine.

How did you test it?

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sroute
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Welcome to the new world of software enhanced optics
In reply to LeicaBOSS, Dec 11, 2013

Or, as one writer put it, the world of Bisto.

http://tashley1.zenfolio.com/blog/2013/12/sony-fe-35mm-f2-8-za-on-the-a7r-the-bisto-lens

This isn't automatically A Bad Thing (tm).

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Mel Snyder
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to Paul1974, Dec 11, 2013

Paul1974 wrote:

Do you shoot all of your photo's through Expodisc? Seriously, it may be because there is no AA-filter. In lab set-ups these things are to be expected. Please attend a photo course or two and enjoy shooting real life images.

GREAT advice!

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LeicaBOSS
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to Paul1974, Dec 13, 2013

Paul1974 wrote:

Do you shoot all of your photo's through Expodisc? Seriously, it may be because there is no AA-filter. In lab set-ups these things are to be expected. Please attend a photo course or two and enjoy shooting real life images.

I understand the snark - but after waking up early, finding a beautiful fog, hauling butt to a nice location and then dealing with rings of color in the images that evening... the use of an ExpoDisc and its importance became clear. This effect does appear in real photos - and understanding it is smarter than pretending it doesn't exist.

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LeicaBOSS
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to Keit ll, Dec 13, 2013

The image below is the first one that made me aware of the issue. Foggy days are kind of the 'easy button' for making so-so locations somewhat interesting.

Given I had just dropped nearly $800 on a slow-ish 35mm... why would I fail to investigate?

SOOC - it's really apparent.

Few additional points:

  • The issue persists with in-camera lens correction OFF or AUTO (although it's not as bad when OFF)
  • The patters DOES change based on aperture, and focus distance... actually focus distance makes a significant difference in shading and color shifts
  • I don't really see the effect with either the Summicron 35mm (pre-ASPH) or Summarit 35mm
  • It's not always feasible to take a "bespoke calibration image" - nor is it necessary. But I do have files at various apertures and near, mid, far focus distances. They clean things up pretty well, if not perfectly.

I'm not an engineer - but I'd bet that Sony's offset microlenses and some under-the-hood processing are part of what's going on. I'm not prepared to only blame the lens - but it's a pain in the ass!

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cwinte
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Re: Here's the Zeiss FE 35mm f/2.8 0 "Bullseye Color Shift"
In reply to LeicaBOSS, Dec 13, 2013

LeicaBOSS wrote:

The image below is the first one that made me aware of the issue. Foggy days are kind of the 'easy button' for making so-so locations somewhat interesting.

Given I had just dropped nearly $800 on a slow-ish 35mm... why would I fail to investigate?

Few additional points:

  • The issue persists with in-camera lens correction OFF or AUTO (although it's not as bad when OFF)
  • The patters DOES change based on aperture, and focus distance... actually focus distance makes a significant difference in shading and color shifts
  • I don't really see the effect with either the Summicron 35mm (pre-ASPH) or Summarit 35mm
  • It's not always feasible to take a "bespoke calibration image" - nor is it necessary. But I do have files at various apertures and near, mid, far focus distances. They clean things up pretty well, if not perfectly.

I'm not an engineer - but I'd bet that Sony's offset microlenses and some under-the-hood processing are part of what's going on. I'm not prepared to only blame the lens - but it's a pain in the ass!

As you say, interesting. Looks like it might be an optical interference effect somewhere. Could even be between some elements that should be bonded and are not, somehow?? Is the lens generally sharp? Do temperatures change the effect?

An idea for how to find out more that I sue sometimes to investigate lens/sensor optics: shoot video and comment what you are doing as you focus in / out and change aperture. try to get some point light and dark 'sources' in your flat field to see how they disperse, especially when OOF.

I look forward to hearing back!

Edit: kinda obvious but you are testing without any filters, yes? I found all sorts of bad from filters and now avoid unless environment very unfriendly.

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