Magenta cast on DP2x

There's always been a slight magenta cast problem with all the Sigma DP's I've had, but the latest camera (DP2X) is much worse now.

It never originally had a strong magenta cast, it was almost invisible in fact but just recently, over the last few months, the cast has become impossible to work with. It is always more prominent on any over-exposed frames, I am doing a lot of auto-bracketing and the 2 stops over just gives me a magenta and white image mostly. Hardly any other colour showing. Really horrible. The 'normal' exposed frame gives magenta cast too but this is more controllable with post-processing. The under exposed one is not too bad but still a faint evidence of magenta cast on them too. What bothers me is it is getting worse and I am unable now to get rid of the cast completley using Photoshop. I have had a little more success with Oloneo Photo-engine, but it should not be necessary to have to do all this drastic tweaking. I use RAW format all the time.

Does anyone else have this bad problem and is there a solution? Unfortunatley the camera was bought just over 12 months ago so I can't claim anything under warrantee.

The sample JPG is of one of the over-exposed frames, converted from RAW.

Any advice welcome.

Thanks.

Stupid question, but did you check your monior? When CFL backlight starts to go bad it will give you magenta cast in darker areas and sometimes does the same thing happens when calibration goes wrong.

barrykap wrote:

There's always been a slight magenta cast problem with all the Sigma DP's I've had, but the latest camera (DP2X) is much worse now.

It never originally had a strong magenta cast, it was almost invisible in fact but just recently, over the last few months, the cast has become impossible to work with. It is always more prominent on any over-exposed frames, I am doing a lot of auto-bracketing and the 2 stops over just gives me a magenta and white image mostly. Hardly any other colour showing. Really horrible. The 'normal' exposed frame gives magenta cast too but this is more controllable with post-processing. The under exposed one is not too bad but still a faint evidence of magenta cast on them too. What bothers me is it is getting worse and I am unable now to get rid of the cast completley using Photoshop. I have had a little more success with Oloneo Photo-engine, but it should not be necessary to have to do all this drastic tweaking. I use RAW format all the time.

Does anyone else have this bad problem and is there a solution? Unfortunatley the camera was bought just over 12 months ago so I can't claim anything under warrantee.

The sample JPG is of one of the over-exposed frames, converted from RAW.

Any advice welcome.

Thanks.

Could you post a (non-overexposed) X3F file somewhere so others can try developing it? My first guess is that the RAW converter (SPP?) is applying some wrong color management profile or something..

barrykap wrote:

Sorry I forgot to mention I am taking +/- 2 stops for HDR set.

If the shot was taken from an auto bracketing sequence (and not manually
set to +2), the broken color balance is due to a bug in all non-Merill
Sigma DPs: the correct white balance is only done for the correctly
exposed shot. In the following test the issue is shown in low-light shots,
but the white balance problem is true for normal light as well:

http://rftobler.at/Photography/Tests/Sigma-DP1-Auto-Bracket/

Note that this is fixed in the Merrill cameras.

Greetings,

Robert

barrykap wrote:

Is the same problem (re non-merril bug) apparant in the SD15 too?

Since I only own the DP1 and the DPx Merrills, I can't say.

Thanks again.

You are welcome.

Greetings,

Robert

PrebenR wrote:

barrykap wrote:

aaaaah. Thanks. That really answers my question perfectly. Yes I was using auto-bracketing as it is obviously convenient to use especially as the 'compact' camera is carried in my pocket without a tripod handy.

I have a SD15 too, which I also take HDR sets on auto-bracketing and this seems to be a lot better, although there is the occasional magenta saturation in these too. But much better than the DP2x. Is the same problem (re non-merril bug) apparant in the SD15 too?

I suppose my solution is to just use the SD15 for HDR's and if I do need to use the DP2x then to use a tripod and manual under/over expose the bracketing.

Thanks again.

Maybe I missed the point, but didn't you say you shoot in RAW? Simply set the WB afterwards to the same in all frames...

HA! You were absolutely just checked it out changing from auto to sunlight got rid of magenta cast.

Now i am curious if he would have shot not with auto wb but sunlight or whatever would he have the same problem ?