Have you ever seen this? strange green cast problem! help!

Started Oct 2, 2010 | Discussions
jungli New Member • Posts: 8
Have you ever seen this? strange green cast problem! help!

Hi there,

I think Ive got a problem with my DP1S, take a look at the strange narrow green cast, have you ever seen this? Anyone can help?

http://www.flickr.com/photos/szymekkrusz/5043813696/in/pool-sigma-dp1photos/szymekkrusz/5043813696/in/pool-345849@N23/

regards
jungli

OP jungli New Member • Posts: 8
Re: Have you ever seen this? strange green cast problem! help!

LMC54 Forum Pro • Posts: 11,808
Re: Have you ever seen this? strange green cast problem! help!

IMO, you have a couple of things going against you.

You are using a DC wide angle lens which generates light falloff at the edges, which was made for small sensors.

You are exaggerating the vignetting effect by using a relatively small aperture of f6 with the DC lens, I know you want good wide focus but the this will bring out the worst in a DC lens.

First thing I would do is get rid of the lens.

Regards,
Larry

jungli wrote:

-- hide signature --

Seriously, can you take DPR seriously?

OP jungli New Member • Posts: 8
Re: Have you ever seen this? strange green cast problem! help!

I don't understand we are talking about Dp1s, there is green cast on left and right border of picture, and the same problem appears for example in landscape views:

LMC54 Forum Pro • Posts: 11,808
Re: Have you ever seen this? strange green cast problem! help!

Ahhh OK, DP1. Same difference in away but the vignette is corrected by software RAW. What software are you using?

Regards,
Larry

jungli wrote:

I don't understand we are talking about Dp1s, there is green cast on left and right border of picture, and the same problem appears for example in landscape views:

-- hide signature --

Seriously, can you take DPR seriously?

Mehdi Amara New Member • Posts: 6
Re: Have you ever seen this? strange green cast problem! help!

This is the green corners issue that affects the dp1, dp1s cameras, to various extent depending on subject, aperture, iso... It seems due to the close distance between the wide-angle lense and the sensor in the dp1, which means that you are far from normal incidence for the rays converging at the egdes of the picture. At such incidences, the transmission of the UV-IR filter is affected which, in addition to the normal vigneting, changes the spectral composition of the light arriving on the sensor. In principle, this could be corrected in software. From my experience, the in camera jpg are well corrected, but there is a fault in SPP 4.0 and above. I myself prefer to use SPP 3.3 (mac) where the effect is present, but less pronounced.
Sorry... hope Sigma will hear us at last!

gustav988 Junior Member • Posts: 43
Re: Have you ever seen this? strange green cast problem! help!

I think you should have your camera replaced. I have never seen that kind of vignetting myself (dp1).

Some seem to have this problem though. One of the sigma peculiarities.

siward Regular Member • Posts: 212
Re: Have you ever seen this? strange green cast problem! help!

Mehdi Amara wrote:

This is the green corners issue that affects the dp1, dp1s cameras, to various extent depending on subject, aperture, iso...

But these examples are very extreme. I have seen DP1s images with no obvious color cast, so I can't believe this is normal. Don't you think this camera has a fault?

S.

OP jungli New Member • Posts: 8
Re: Have you ever seen this? strange green cast problem! help!

Usually I use SPP4.1 and always shoot in RAW. Thanks for quick replies, scene with the fish is extreme so I noticed it but earlier I have no clue about that. Now I'm searching my pictures and I'm much more dissapointed.

Has anyone can tell that DP1X will be free from this problem? this is trueI only issue? Also I have Dp2 and SD14 and never seen this cast before, it is true that on some of my pictures are more or less green casted.

Is it possible to give it ti Sigma warranty as a damage of camera?

anyone has expirience?

best regards
jungli

JW PHOTO Veteran Member • Posts: 3,012
I totally agree with gustav988.......

Your camera needs to be replaced! Sigma seems to have a QC issue with most of their line of SDxx and DPx cameras. I have a SD14 that I bought new and it has none of the problems that many people seem to have had with that model, but if you check this forum you'll see many SD14 owners had lock-ups, green casts and other issues. The earlier DPx cameras seem to have had a few similar problems also. We all understand that a bad sample might make it through the inspection process, but it seems that some of these inspectors at Sigma didn't show up for work one or two days a week. I would think that it would be very easy to check either the SDxx or DPx series cameras for the dreaded cyan/green cast before it ever leaves the factory, by duplicating a problem scene and checking your results. I sometimes get the impression that these cameras just come off the line, are stuck in a box and shipped on their merry way. The buyer then is the inspector! I would contact Sigma and get the camera back to them as that amount of green cast is unacceptable in any camera.

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lighttripper Contributing Member • Posts: 677
Re: Have you ever seen this? strange green cast problem! help!

jungli,

The green cast in image margins was clearly present in the DP1 cameras I have handled (one DP1 and one DP1s). The green cast in the images you show do seem especially excessive. Did you increase density or saturation of the images?

There has been discussion in the past on this forum that the green cast varies between individual cameras and even not present in some copies. Since this is being caused by a single lens at a single focal length, one would think Sigma could get its software to correct for the green cast. I've tried using a variety of earlier SPP software to see if the green cast is managed better, but it is always present to some degree.

Theoretically, stopping down the lens to, say, F8 and focusing with manual some 2 audible clicks past infinity should give yo the most optimum light path from the back lens element to the sensor, diminishing the greenish cast. This is what I do, but the cast is still present in my DP1s, though substantially less apparent than in your photos.

I just add/subtract incremental amounts of red and green to the image margins--which masts the cast to a satisfactory amount for me. Otherwise, the image quality is stellar for such a little camera with a fine lens.

Roland Karlsson Forum Pro • Posts: 28,124
Re: This green cast is why ...

This green cast (and other similarly irritating problems) is why I think it was very sad that Sigma was the only camera maker that uses Foveon. They have proven again and again that they are not competent to make cameras.

For some reason all the different versions of DP1 has this problem -- more or less. And it seems to vary wildly between camera units. It also varies greatly with what software you use. And also with what setting you use.

I am guessing - but keep in mind that it is only a guess - that the camera has very strong vignetting that is corrected in software. The vignetting is color dependent and the X3 to RGB conversion depends on exposure. This makes it very hard to find an acceptable correction for the vignetting.

Moreover - the actual sensor units probably vary greatly from sample to sample. So - it makes the task even harder. All this makes the green corner problem very elusive. Some sees it and some dont.

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Roland

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PatrickC Regular Member • Posts: 151
Re: Have you ever seen this? strange green cast problem! help!

This agrees with what I've seen (DP1s). I have a couple of shots with the green caste in one or two corners, where the vignetting is also especially visible. In the worst one, the light is mainly coming from a window that is in the opposite corner (diagonally) from the green/vignetting. Also, the green has only shown up so far at f4 but not above, though this is a very small sample. When there's enough light for no visible (obvious) vignetting, then no green caste.

Mehdi Amara wrote:

This is the green corners issue that affects the dp1, dp1s cameras, to various extent depending on subject, aperture, iso... It seems due to the close distance between the wide-angle lense and the sensor in the dp1, which means that you are far from normal incidence for the rays converging at the egdes of the picture. At such incidences, the transmission of the UV-IR filter is affected which, in addition to the normal vigneting, changes the spectral composition of the light arriving on the sensor. In principle, this could be corrected in software. From my experience, the in camera jpg are well corrected, but there is a fault in SPP 4.0 and above. I myself prefer to use SPP 3.3 (mac) where the effect is present, but less pronounced.
Sorry... hope Sigma will hear us at last!

Gary Dean Mercer Clark
Gary Dean Mercer Clark Veteran Member • Posts: 5,606
Re: Have you ever seen this? strange green cast problem! help!

Never seen a strange green cast problem.

http://www.garymercer.us

WHNewell Senior Member • Posts: 1,400
Re: I totally agree with gustav988......not

I left a comment on your flickr page. The vignetting or green cast is more than just a border vignette which can occur with certain wide angle zoom lenses whether it be a 35mm film camera or a DSLR. It appears you may have exaggerated it in your PP. What software are you using to process your images or are you using in-camera jpegs?

My recommendation would be to contact Sigma Service Center via a phone call and get some technical advice. Perhaps they will agree the camera needs replacement/adjustment. Also, do you have the latest firmware installed for your camera?
--

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Wally

OP jungli New Member • Posts: 8
Re: Have you ever seen this? strange green cast problem! help!

Thanks for replies,

so I think I will contact local dealer for replacement or fixing the problem, as far as I understand this is specific problem of some of examples dp1 and dp1s. I wonder how the service will respond for this, will replace te sensor or replace for another new dp1s.

I hope that will not be continued in dp1x, btw first picture exif is f6 speed 200 so that is not a problem of open lens.

Tommorow I will do some more tests and shots to prove for service that my dp1s is damaged...

Sigma I love you for the foveon but WHY???? why bodies are so bugged including sd14....

I use raw and SPP 4.1 never shoot in jpg, latest firmware...

the cast is different depending of light and conditions, f stop etc, but it is and for me as I see the photo of fish on my screen is totally unacceptable, there is no way to fix it in PP without croping but this is not a solution

regards

DMillier Forum Pro • Posts: 20,895
Looks like my Kodak 14n

I haven't seen this with my DP1 thankfully. But it looks remarkably like the problems my 14n had. Kodak built correction factors into the firmware and made you select a "lens type" for every lens.

It didn't work and the result was the famous italian flag: magenta on one side, green on the other. It was very camera and lens dependent and some people took to shooting a blank frame with a transulucent white filter over the lens, then subtracting the two frames one another.

I did a test once, shooting a picture of a white wall with my 350D and 14n. When viewing the shots on screen, the Canon shot was a nice even grey. The kodak was a kalidoscope of colour swirls. They had no hope of correcting that mess, just hoped you wouldn't notice. In the end after endless firmware updates they designed a new sensor/mainboard and offered to swap it out (for another £1200).

jungli wrote:

Hi there,

I think Ive got a problem with my DP1S, take a look at the strange narrow green cast, have you ever seen this? Anyone can help?

http://www.flickr.com/photos/szymekkrusz/5043813696/in/pool-sigma-dp1photos/szymekkrusz/5043813696/in/pool-345849@N23/

regards
jungli

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Jerry_R Regular Member • Posts: 468
Re: Have you ever seen this? strange green cast problem! help!

jungli wrote:

there is no way to fix it in PP without croping but this is not a solution

Hi Jungli

Maybe there is a workaround, exactly the same as I used for M9 and "red corners" on ultra wide angle lens.

You can create presets in LR - with graduated filter and color cast applied. The color cast depends on your color shift and white balance.

You would need to have few of them with different strength. Plus variants for left\right (or top\bottom). I checked that on your JPGs and it solves somhew the issue.

I write somehow - as it is manul activity, depending from picture to picture. So it definitely is not professional approach and workflow.

I would contact service.

-- hide signature --

Best Regards,
Jerry_R

OP jungli New Member • Posts: 8
Re: Have you ever seen this? strange green cast problem! help!

Jerry,

I think there is nothing to discuss, DP1s has a fault period it cant be done by some presets in LR this is way to worthless. The ugly truth about sigma is that they cant manage with a problem which seems to be on all dp1s, more visible or less but it is.

Cant wait till monday then I will discuss it with Polish service, hope that will respond for this corectly.

I'm very sad about this situation, love foveon work but faults are much more dissapointing, also I will try to contact Sigma Japan, maybe Shizno Fukui or Kazuto Yamaki will give me some answers

regards
pozdroofka Jerry:)

Zone8 Forum Pro • Posts: 17,276
Re: Looks like my Kodak 14n

DMillier wrote:

I haven't seen this with my DP1 thankfully. But it looks remarkably like the problems my 14n had. Kodak built correction factors into the firmware and made you select a "lens type" for every lens.

Not quite the full picture regarding the Kodak DCS14n. The Italian Flag syndrome actually occurs with many digital cameras in certain conditions and seems directly related to the lens being used. For the 14n there is a list compiled of lenses that can be used without exhibiting those traits - here's the link:

http://www.sveido.com/lensdb/search.asp?camera_id=1&lens_id=0&status=0&description=&source=&action=foo

I have a Tamron 28-200 (came with the 14n) that was superb - except for certain subjects, exhibited that IF phenomena and seemed also to relate directly to the actual zoom FL used.

I got a Vivitar 28-100 and that exhibits NO IF problems, so clearly lens dependent. I checked the posted listing at the time so that I could buy a lens that was said to be free of the IF trait - and it worked fine. I did also find setting Type 1 for the Tamron produced a majority of shots without the IF appearing but that also was dependent on the subject matter and lighting and the actual FL used on the zoom.

Hope that clarifies in regard to your (I felt unfair) too sweeping statement.

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Zone8

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