PlymouthWoodworker Loc: Plymouth, MA

Longtime participant, but my first question to the group. I just purchased a B+W 67mm ND 3.0-1,000X with Single Coating filter. My purpose is to shoot long exposes of water, etc., that show motion/blur. I gave it a try today and got wierd results. Here's what I did: using a Nikon D7100 with Nikon 18-140 lens I composed and focused my shot on a tripod with no filters in place with the camera in aperture priority mode (set at f/16). I then set the camera to manual focus and manual exposure modes and mounted the 10 stop ND filter and lens shade. Then I increased the expose time to compensate for the filter and took 3 consecutive shots. In all shots the focal length was 27mm and the ISO was 100. Shots 1 and 2 were taken at 25 seconds and f/16, shot 3 was 60 seconds f/20. As you will see below, shot 1 looks OK (these are jpegs straight out of the camera, but the RAW files show the same results). Shot 2 (everything identical to shot 1) has a horizontal purple band. Shot 3 is even worse. I have other examples if needed. Can anyone explain the purple banding on some shots and not on others?
Thanks much

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Fred Harwood Loc: Sheffield, Mass.

Condensation?

Navywife66 Loc: NC

Did you cover the eye piece? It leaks light during long exposures that has been known to cause this type of banding.

PlymouthWoodworker Loc: Plymouth, MA

Thank you Navywife66. That's an excellent point. I will try that.

Longshadow Loc: Audubon, PA, United States

And the second is more exposed than the first.

Navywife66 Loc: NC

Your welcome, let me know if this works. I too have a brand new ND filter which arrived today. It’s a variable 10 stop too but it’s from Breakthrough Photography. I’m excited to try it myself. I’ve studied about the use of it extensively and when I read your post I didn’t see that step. I hope that it works!
T

rgrenaderphoto Loc: Hollywood, CA

Bingo! Light leak through the viewfinder has ruined many long exposure shots. If your camera does not have viewfinder shutter, a small piece of gaffer tape will work.

picsman Loc: Scotland

I put the camera strap over the viewfinder to block out the light, but only on non windy days and it works. Otherwise use some black material, tape etc to cover the viewfinder.

jerryc41 Loc: Catskill Mts of NY

Some info about covering the viewfinder. The first links shows an example of your problem.

https://www.unlockcreativephotography.com/do-you-need-to-cover-the-viewfinder-long-exposure.php
http://photographio.com/cover-viewfinder-long-exposures/
https://improvephotography.com/2475/night-photography-light-leak-leakage/

PlymouthWoodworker Loc: Plymouth, MA

That was it!! Thank you to all who answered.

FiddleMaker Loc: Merrimac, MA

I am glad I read this entire thread because I never knew this would happen. I think the D500 and probably the D850 have built-in viewfinder shutters for this purpose of blocking light. But my D750 does not. I would have to use black electricians tape.

Navywife66 Loc: NC

Your welcome, glad was an easy fix! Now create some magical pics!

rydabyk Loc: Florida Panhandle

Until I started shooting long exposures I never knew what that rectangular rubber thing was that came on the (Canon) camera strap, only then did I find out that it fits over the viewfinder (after removing the eyepiece) to block light from entering. The thing that bugs me is that I've never been able to find any extra ones to buy. Anyone know of a source?

Thanks!

Navywife66 Loc: NC

Probably eBay or adorama..

rgrenaderphoto Loc: Hollywood, CA

No, no, no. Electrical tape will leave a residue. Use Gaffer tape, which will not leave a residue.