deddard
newbie
Reged: 11/03/2008
Posts: 45
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Anyone else had any problems with polarizers on D60 (or any other DSLR)?
I went to Duxford at the weekend and hammered my SD cards - great!
Until I looked at the results.
I had the camera exposure set on Prog most of the time - it seemed to cope well with exposure.
I shot in Raw+ basic, and many of the shots are fine.
However, I put on a polarizer halfway through, to saturate the sky and slow the shutter a bit.
The results were awful. when I checked the exposure settings at the time they seemed fine, but for some oddball reason it seems to have given everything around 1/1000 at F5.6 even with the polarizer on at ISO 200.
The shots are a good two-three stops underexposed. One stop would be fine (I usually dial in 1/3 stop anyway) so the darker areas are full of noise if I try to recover the picture.
My wife's D60 coped well. All the settings were identical including matrix metering, ISO etc. The only difference is that she didn't use a polarizer and had D-lighting on.
The pics also look hugely vignetted. the centre is differently exposed to the edges - not the usual vignette you'd get with a wide lens (I was using 200mm mostly) but a real problem.
The filter is a middle-range Hoya (£30 ish) circular polarizer .
Anyone have any ideas?
Edit...........
Could it be a linear polarizer? could the filter be back to front? a bit of reading on the net suggest something like this.
Edited by deddard (14/07/2008 22:45)
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4241
Loc: Really Here In Name Only
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Could it be a linear polarizer?
Sounds very likely to me.
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could the filter be back to front?
I think you'd notice, for the reason that screw threads are invariably heterosexual.
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AlexMonro
addict
Reged: 05/06/2006
Posts: 689
Loc: Exeter, Devon (and Somerset so...
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Sounds like it could be a linear polariser, which could cause problems with the metering (and AF as well!). Have you used this polariser before?
Back to front could also explain it, though I'm not sure how it could've happened (I dropped my CPL once and it sprang apart. Fortunately nothing broke, and I got it back together the right way round first try  ). If you've got an LCD computer monitor, a simple test is to hold the filter up to the screen and look through from the lens side. If you can rotate it so that it goes almost completely black, it's correct.
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deddard
newbie
Reged: 11/03/2008
Posts: 45
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Quote:
Sounds like it could be a linear polariser, which could cause problems with the metering (and AF as well!). Have you used this polariser before?
Back to front could also explain it, though I'm not sure how it could've happened If you've got an LCD computer monitor, a simple test is to hold the filter up to the screen and look through from the lens side. If you can rotate it so that it goes almost completely black, it's correct.
Thanks for that - I did the test and it seems to be a circular polariser, and the right way round - I'd wondered if the glass had been put in the wrong way round in the factory (or dropped and hastily re-assembled somewhere along the line).
So it's a circ rathern than a linear, and no, I haven't used this one before in anger (not exactly been a polariser summmer!)
So where now? I guess I can test it on my Wife's D60 to see if it produces the same results or see if it could be the camera causing problems.
Your point about the AF is interesting - the shots do look slightly out of focus.
Could it be the quality? I've got a couple of higher-end Sigma circ polarisers here, so it may be possible to run a few tests there. It's as if the meter ignored the polariser, but where the weird vignetting came from I don't know.
I guess I'll have to ask Duxford to get all those Spitfires back so I can do the test shots!
Edited by deddard (15/07/2008 08:52)
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AlexMonro
addict
Reged: 05/06/2006
Posts: 689
Loc: Exeter, Devon (and Somerset so...
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Quote:
Thanks for that - I did the test and it seems to be a circular polariser, and the right way round - I'd wondered if the glass had been put in the wrong way round in the factory (or dropped and hastily re-assembled somewhere along the line).
So it's a circ rathern than a linear, and no, I haven't used this one before in anger (not exactly been a polariser summmer!)
Just a thought - you probably did this already, but did you try holding the filter up to the LCD the wrong way round (lens side towards LCD)? With a circular polariser, you should see little change (possibly a small colour shift) as you rotate it, I think a linear polariser would give the same effect as the propper way round (haven't got a linear to test this theory though).
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So where now? I guess I can test it on my Wife's D60 to see if it produces the same results or see if it could be the camera causing problems.
Your point about the AF is interesting - the shots do look slightly out of focus.
Could it be the quality? I've got a couple of higher-end Sigma circ polarisers here, so it may be possible to run a few tests there. It's as if the meter ignored the polariser, but where the weird vignetting came from I don't know.
I have a middle of the range Hoya CPL (the green box, I think single coated) and I've never had anything like this, though I only use that on a bridge compact (Fuji S9500) and manual film (Nikon FM2) which I don't think use any clever polarisation dependent half silvered mirrors. I use a low end Kood CPL with my Fuji S3 DSLR with no problems.
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deddard
newbie
Reged: 11/03/2008
Posts: 45
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I did try the polariser the wrong way round, and it gave the expected results.
This Hoya Filter is in a blue pack, which is I think the lower end of Hoya's range, but supposedly better than the cheapy no-names.
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