Odd effects on long exposure shots

[LesC2009]

Tried some long exposure shots on a recent trip to Jersey and I'm trying to work out what's caused the odd effects on these shots.

Please ignore the fact the photographs are underexposed; I took shots at a variety of settings but the underexposed shots show the effects more clearly. Also please ignore the vignetting in the extreme top corners - I'm aware this is from the polarising filter fitted to the front of the Lee holder.

I used a Hitech 10 stopper along with a Lee landscape polariser, on a EOS6D + EF24-70 F2.8L II lens.

The first shot (long exposure 1, focal length 24mm, iso 100, f16, 35 secs ) shows some darkening in the sky to the top right corner of shot; I'm not too bothered about that - presumably uneven polarisation. However the top left portion is rather strange - there appears to be a darker vertical line running from the top of shot down to the land, about a quarter of the way in from the left?

I'm wondering if it's flare/reflections between filters/light leakage? I'm presuming the filters are the cause rather than the camera? No such problems with shorter exposures using just the polariser.


The 2nd shot of the lighthouse (long exposure 2, focal length 44mm, iso 100, f16, 15 secs) seems to show a darker area to the right sight of the frame, curving inwards towards the top. Again, could this be flare/reflections between filters/light leakage?

I've not noted similar effects before with this 10 stopper (with a different camera/lens combination) but then again, these shots were taken far from ideal conditions - strong overhead midday sun.

Inevitably, I guess I'll need to try some test shots under more favourable conditions to see if it happens again.

[tesarver]

Re: Odd effects on long exposure shots

Those can be caused by the polarizer filter. Polarizers work best at 45 degrees from the sun. Any variances can cause some parts of the sky to become darker in an uneven look.

Tom

[Parsen66]

Re: Odd effects on long exposure shots

Those can be caused by the polarizer filter. Polarizers work best at 45 degrees from the sun. Any variances can cause some parts of the sky to become darker in an uneven look.

Tom

I'd agree with Tom's statement above. And also add that stacking filters can cause light leaks and affect the image is rather strange ways. I assume the polariser was screwed to the lens and the Lee slid down in front of it?

[tesarver]

Re: Odd effects on long exposure shots

. Polarizers work best at 45 degrees from the sun.

Tom

Slight error, that should say 90 degrees from the sun.

[LesC2009]

Re: Odd effects on long exposure shots

Thanks chaps :) The polariser was fitted on the front of the lee holder on the 105mm polariser ring. I think I may have taken some without the polariser too that exhibited some lesser effects but can't recall for certain (should have made a note at the time!) Also remembered I had a skylight filter between lens & lee holder too. I'll try a few test shots soon but probably wont be able to receate the effect - I hope!

[Parsen66]

Re: Odd effects on long exposure shots

So at one point you had three different filters at once? Sounds like light leaks to me but I could be wrong. I much prefer a screw on filter personally

[jimsphotography]

Re: Odd effects on long exposure shots

At 24mm the Lee CPL is too thigh and causes vignetting. The best CPL for 24mm wide angle lenses is the ultra thin Heliopan - which even is reasonably OK at 16mm.
Can I ask how many filter slots you have on the holder ? It should have only one for the ND and then the adapter ring for the CPL - any more and the thick Lee CPL would seriously interfere with the shot.
Hope this helps
James

[jimsphotography]

Re: Odd effects on long exposure shots

Just read through this again.
Some advice worth trying -
1) you MUST always remove any screw on filters before fitting the Lee ( or any other) filter holder.
2) did you cover the eyepiece so no light leaked in from there ?
3) does your your 10 stop ND filter have a felt edge ( like a Lee one has) to seal it against light leakage? If so, make sure you fit it properly so no leakage takes place.
4) experiment taking shots with the 10 stop ND alone fitted to see if the darkening area still occurs
5) Make sure the edge of the ND filter is fitted square on and not at an angle.

Let us know how you get on.
James

[LesC2009]

Re: Odd effects on long exposure shots

James,

Thanks :)

Used the new Lee landscape polariser which is much thinner that the old one - similar to the Heliopan. Vignetting from this was only in the extreme corners.

1) you MUST always remove any screw on filters before fitting the Lee ( or any other) filter holder. Guilty as charged, I still had a skylight on ;)
2) did you cover the eyepiece so no light leaked in from there ? Yes but I had some difficulty getting in on properly so that could be a factor
3) does your your 10 stop ND filter have a felt edge ( like a Lee one has) to seal it against light leakage? If so, make sure you fit it properly so no leakage takes place. Yes, it does
4) experiment taking shots with the 10 stop ND alone fitted to see if the darkening area still occurs
5) Make sure the edge of the ND filter is fitted square on and not at an angle.

Thanks for the tips - will do some testing :)

[jimsphotography]

Re: Odd effects on long exposure shots

Looking forward to seeing the results
James

[pelliott1954]

Re: Odd effects on long exposure shots

Interesting thread this, please keep us posted with updates

Regards Paul

[collywobbles]

Re: Odd effects on long exposure shots

I would agree with what has already been said. That's a lot of extra glass infront of your lens. I would even remove my UV filter if fitting a polarizer.

[LesC2009]

Re: Odd effects on long exposure shots

Finally got round to doing some testing, only in the garden but similar conditions, bright overhead midday sun....

I tried shots both with 10 stop filter & with 10 stop + polarising filter & was unable to recreate the earlier effects (this even with a skylight filter attached to lens too). The only thing I saw was some flare at times which was to be expected.

I did notice when fitting the 10 stop filter that due to the positioning of the felt gasket, it is really important to place the filter in exactly the right position, even a millimetre or two either up or down will leave a little gap for light to creep in (I fitted filter to holder off camera & checked positioning with another adaptor ring in place). I also made sure the rubber eyepiece cover was correctly fitted although even leaving it off seemed to have no discernible effect.

So other than the possibility that I did not have the 10 stop filter positioned spot-on I can only assume the conditions at the time of the previous shots - bright sunlight/refective seas or a combination of both factors were the cause.

Thanks all for your input :)