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Author Topic: Images turning colours-why?  (Read 482 times)

John R

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Images turning colours-why?
« on: February 13, 2017, 02:54:23 PM »

Anyone seen this before: longer exposure=dark purple; shorter exposure=dark green. I have not had chance to examine my 16-45 Pentax lens, but I suspect it is the culprit, since everything went back to normal after I changed out said lens. At first I suspected the two filters, 3X factor and polarizer, but as I said, everything went back to normal after I changed out lens. Would a sticky aperture cause this?

JR

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Eric Myrvaagnes

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Re: Images turning colours-why?
« Reply #1 on: February 13, 2017, 05:00:41 PM »

That is truly bizarre.

If you give the same exposure, one with slow shutter and one with fast, but compensating with aperture, does it give you the same effect?
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John R

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Re: Images turning colours-why?
« Reply #2 on: February 13, 2017, 06:17:55 PM »

At this point Eric, I really don't know what went wrong. First I had trouble with my SD card, camera would not respond card error. Changed card, everything seemed fine, so I thought it was card issue. I shoot jpeg and raw together. I  proceeded to photograph. First seven shots seemed Ok, then No8 forward came out green or purple, so I changed aperture to get fast shutter speed. Next image was purple, this went back and forth as I changed aperture. then I removed the two filters, same result. If I tried to compensate for white snow, it would go purple; if I underexposed or shot with no compensation, it would go green. Then finally I changed lens and everything seemed fine. I put filters back on, again fine. I guess I will try the lens again tomorrow to try and pinpoint problem. I thought it was bent aperture lever, but it seems fine by eye. It's almost like CA out of control! Still scratching my head.

JR
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John R

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Re: Images turning colours-why?
« Reply #3 on: February 13, 2017, 06:37:03 PM »

Just tried the lens again with about 6 shots, seems fine. Also tried SD card I thought  was defective, seems fine also. What the heck? Perhaps it is the no-name cheap batteries I bought. About two years old now. They seem to show 2/3 power as soon as I take one shot. So will try and change the battery also. Just checked, the raw images are also off-coloured. Still, how will Lightroom remove all that CA- ha, ha...

JR
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BrownBear

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Re: Images turning colours-why?
« Reply #4 on: February 13, 2017, 07:01:01 PM »

I've seen the same type of color shifts with DSLRs when stacking ND and POL filters to knock down light and allow long exposures in bright outdoor light. As I rotated the POL, the colors could really shift.

Don't remember the details all these many years later, but I also experienced color shifts with a couple of varieties of film and long exposures.

Based on my experience, you had winkyjinky things going on with the stacked filters.
« Last Edit: February 13, 2017, 07:37:57 PM by BrownBear »
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Eric Myrvaagnes

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Re: Images turning colours-why?
« Reply #5 on: February 13, 2017, 07:49:55 PM »

It sounds like the solution has two parts:
1.   Don't use filters, and
2.   Convert everything to monochrome.

 ;D
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-Eric Myrvaagnes    (A sampler of my new book is on my website.)
http://myrvaagnes.com  Visit my photo website. New images each season. Also visit my new website: http://ericneedsakidney.org

BrownBear

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Re: Images turning colours-why?
« Reply #6 on: February 13, 2017, 08:08:01 PM »

It sounds like the solution has two parts:
1.   Don't use filters, and
2.   Convert everything to monochrome.

 ;D

Or Solution #3: Use high grade filters of the same brand. In my case the issues started when stacking Hoya and Schneider. Switched both to Schneider and the issue (mostly) went away.
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John R

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Re: Images turning colours-why?
« Reply #7 on: February 13, 2017, 08:45:50 PM »

Thanks for the interest, Eric and Brown Bear. I think Brown Bear has it right. Have to stick with one brand or not use more than one filter. I like a little blur in rapid moving water, doesn't have to be a lot. I over did it when I turned the polarizer to maximum.

JR
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BrownBear

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Re: Images turning colours-why?
« Reply #8 on: February 13, 2017, 09:09:52 PM »

...a little blur in rapid moving water....

That's what my shoot called for- a model in front of a blurred waterfall. But the shoot was scheduled midday in direct sunlight.  Don't ever want to see skin tones like that again!  :o 

Fortunately I had additional filters in my location kit. I was able simply to change filters and finish the shoot. Kinda settled me on carrying only one brand of filters on any future shoot, though.
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