I had a problem with some long exposure photos of a beach in sunlight. The overall exposure is fine, but the clear sky turned out very uneven, from very dark blue to almost white.

D700, 16-35mm, ISO 100 (low-1), F/22, 8 seconds. Singh-Ray Var-ND-Duo set to block 8 stops.

Any idea what caused this? I have a whole bunch of photos from the same shoot with the same problem, so the problem is consistent.

I'm guessing it may be the Var-ND-Duo and the way it's mechanism variably blocks light, but before I go spending money on one of their new 10-stop filters, I'd like to be sure.

Thanks!!!

Attachment #1, (jpg file)

While a lot of trouble at this point, it looks like a lens filter is the issue. I'd try reshooting without any filter on the lens.

I have seen this sort of thing on wide angles and polarizing filters.

David

"Sawed that board three times and it is still too short... "

Visit my Nikonians gallery.

>While a lot of trouble at this point, it looks like a lens
>filter is the issue. I'd try reshooting without any filter on
>the lens.

The lens works great otherwise. I have shots of the same coastline without any filters (but different exposure settings obviously) which all look fine.

>I have seen this sort of thing on wide angles and polarizing
>filters.

Then perhaps it's the polarizing part of the vari-nd-DUO? Maybe a regular Vari-ND would work better?

Thanks!

P.S. Is the correct forum for this question? Maybe the Landscape forum would be better? Wasn't really sure where to post...

Your problem is with the polarization part of the filter. Polarizers don't work well on wide angle lenses when the sky is in the shot. Polarizers have the strongest effect when 90 degrees to the sun, if you point the camera directly towards the sun or 180 degrees from the sun (sun at your back) then the polarization effect is basically zero. Wide angle lenses can allow large areas of the sky to be in the photo so this effect looks just like what you see in your photo.

Pete Wilson
Nikonian from Lake Orion, Michigan
My Nikonians gallery

Nikonians membership - My most important photographic investment, after the
camera

Looks like David and Pete have you covered. What you are seeing is very common with wide-angle lenses when using polarizing filters.

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Joseph K
Seattle, WA, USA

D700, D200, D70S, 24-70mm f/2.8, VR 70-200mm f/2.8 II,
50mm f/1.4 D, 70-300mm f/4.5-5.6 VR, 18-70mm f/3.5-4.5 DX

Makes sense now. Thanks everyone!