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05-18-2018, 05:58 PM   #1
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Can anyone explain what caused this?

Note the squiggly looking bands of light across the image. This is with the K-1 and the DFA 24-70 @ f/16, 30 seconds and ISO 100. Using a 10 stop ND filter. I have images before and after that do not show the effect. This occurred at several different locations on two different days. The pattern is exactly the same on all images (over 30).

I guessed it was light entering the viewfinder but I've since tried to duplicate and cannot so far. Most images were taken using liveview but some were through the finder.

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05-18-2018, 06:05 PM   #2
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Is your sensor clean, I really don't know, but I'm going to take a wild guess. Maybe you wet cleaned sensor, and some residue stuff was left? Or something else? As it looks clouded over/misted in the image. I guess does the sensor look clean? Hope you find the problem (and can fix it easily)
05-18-2018, 06:08 PM   #3
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Sensor has never been wet cleaned. And I have several day's shots (400-500) taken after that show no sign of the pattern.
05-18-2018, 06:39 PM - 1 Like   #4
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Hi John, this article may help. Good luck.

Complete Guide to Neutral Density filters ? Part 4 Problems & Solutions | Discover Digital Photography

05-18-2018, 07:12 PM   #5
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Is this a slot-type filter or screw-in?


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05-18-2018, 07:35 PM - 2 Likes   #6
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Your first guess is probably correct. With a 10 stop ND on the lens, any light coming in the viewfinder would be significant. Since it doesn't appear on previous or following shots, it's very unlikely to be the camera or its sensor. It's handy to make a small viewfinder cover (use a small slab of foam polyurethane with double stick tape) and use it anytime you're making a long exposure because some light leaks can get in. It's also possible that there were light leaks elsewhere but not all that probable. The problem is when you aren't putting much light on the sensor (high ISO and/or long exposures), just a small leak in bright conditions can overwhelm the image being formed (particularly in darker areas). Makes no difference whether LV or VF because the mirror is in the same position for each when the exposure is made. Next time you see this (if you do), repeat the shot covering the viewfinder and see if it makes a difference.
05-18-2018, 08:11 PM   #7
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I have a ten stop nd filter and I never had such a problem... I never covered the viewfinder. Could it be poor filter?

05-18-2018, 09:04 PM   #8
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QuoteOriginally posted by pjv Quote
Hi John, this article may help.
Thanks I'll check it out
QuoteOriginally posted by stevebrot Quote
Is this a slot-type filter or screw-in?
Screw on. I've used the same one before with no issues.
QuoteOriginally posted by Bob 256 Quote
It's handy to make a small viewfinder cover (use a small slab of foam polyurethane with double stick tape) and use it anytime you're making a long exposure because some light leaks can get in.
Yep. Thanks. I actually have one I built but forgot to put it on. See post #25 in this thread for mine: K-3 underexposes with ND filter - Page 2 - PentaxForums.com But the effect I see with this shot is not like what I was getting when I built this cover.
QuoteOriginally posted by IgorZ Quote
I have a ten stop nd filter and I never had such a problem... I never covered the viewfinder. Could it be poor filter?
Good guess, but no. The filter is from Breakthrough Photography. By far the most expensive filter I've ever bought. And I've used it for the same type of shots for a couple years with no issues.
See the thread linked above for images showing what often happens if you don't cover the view finder. But it depends on the light and the angle of the light.
05-18-2018, 09:25 PM   #9
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QuoteOriginally posted by jatrax Quote
But it depends on the light and the angle of the light.
Perhaps the filter is delaminating?


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05-18-2018, 09:38 PM - 1 Like   #10
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QuoteOriginally posted by stevebrot Quote
Perhaps the filter is delaminating?
Thanks Steve, careful examination shows no sign of any issues with the filter.

I tried this afternoon to duplicate the effect, same camera, lens and filter and the images look great. I'm still leaning toward light through the viewfinder but I've never seen anything quite like this before.
05-18-2018, 09:47 PM   #11
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Gaps in the clouds?
05-18-2018, 09:53 PM - 1 Like   #12
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QuoteOriginally posted by aoeu Quote
Gaps in the clouds?
I had the same thought, some light rays coming through the clouds. But the bands are identical in all images. From three completely different locations. So no way it can be that.
05-18-2018, 11:05 PM   #13
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QuoteOriginally posted by stevebrot Quote
Perhaps the filter is delaminating?
That was my first thought too.

De-lamination is common with polarisers, I have never seen it occur with my Lee Polariser or ND filters. Though with certain mid to low tier filters I have seen all kinds of manufacturing disasters.

This is isn't a simple matter of light entering the viewfinder which invariably leaves horizontal lines on the image, this could be a bizarre combination of things going wrong at the same time - I'm looking at the fogging and deep magenta cast that appears on the right side of the shoreline.

You weren't trying to use pixel shift by any chance?

Last edited by Digitalis; 05-18-2018 at 11:23 PM.
05-18-2018, 11:13 PM   #14
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I would clean the filter. Remove it and clean it. It looks like smudge marks of some sort of light oily residue that got smudged around somehow. It would disappear in warm/hot weather but could be particularly visible in humid conditions. Sort of like how you can notice the smudge marks on your windshield early in the morning but after it all warms up it seems clear.
05-19-2018, 02:48 AM   #15
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Same pattern over multiple days? Exact same orientation of the bands? I'm thinking it might be unlikely to have a screw on filter in the exact same orientation if it's been on and off.

More sample images might help. Good luck!
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