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06-14-2008, 05:41 PM   #16
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Ah, thanks for clearing that up, RB. So, which model Cokin are you using with the FA? The particulars of your setup makes me wonder whether there's some interaction going on with the Pentax multi-coating, the Cokin's coating(s), and the sensor.

06-15-2008, 12:35 AM   #17
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Maybe Ghost Hunters will buy the filters off you for their show on the SciFi Channel.
06-15-2008, 05:21 AM   #18
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QuoteQuote:
The extra lights are reflections off the back side of the filter being sent towards the sensor.
isn't this the type of thing that pentax tried to git rid of with there 'ghostless' UV filters? I have one of those.
06-15-2008, 05:42 AM   #19
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QuoteOriginally posted by séamuis Quote
isn't this the type of thing that pentax tried to git rid of with there 'ghostless' UV filters? I have one of those.
Even with multi-coating filters, you can't eliminate all reflections, and night pictures with a strong light sources are prone to this. Since most of the frame is dark, the spots will be very obvious.

06-15-2008, 06:49 PM   #20
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I have seen this problem (''op'') with cheap filters. Been there, done that, learned the hard way..Now I only use B+W UV haze 10 filters or Polarizers...Problem solved.
06-15-2008, 07:33 PM   #21
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This is why I don't use filters except for..

Circular Polarisers and ND grads. I do not use any type of "lens protection" filters like skylight or UV as they may have a detrimental affect on the images as you have shown.
06-15-2008, 11:10 PM   #22
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Shoot a subject like a candle in a darkened room or a lighted point source like a street lamp at night and you can tell if you've got an el-cheapo filter or not. Less of a problem in the day but with night shots I usually remove any filters I have in front of the lens.

06-16-2008, 04:33 AM   #23
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Hoya UV... really great during the day... but at night...



Granted I was using a flash and those reflective stripes on our bunker gear are an absolute nightmare of reflections when trying to take pics, but I only got the ghosting when I had the filter on.

Pat
06-21-2008, 08:39 AM   #24
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Its not my FA200.2.8 problem. Looks like it happens with any lens/filter combination. I even thought for a moment it was related to my istD body, but this new test, shows its happening too with my new K20D and Fa 135/2.8 IF, with a good filter.

Attachment 14287

I will do some more tests with all my lens arsenal, since all of them, except my F17-28 zoom and my SMC-A 15/3.5 have protective filters.

I will post later my findings.

RB

Last edited by rburgoss; 08-14-2008 at 07:37 AM.
06-21-2008, 01:46 PM   #25
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More evidence for two propositions in the use of filters:

1) Buy the best quality coatings that you can afford, preferably applied to solid glass (not sandwich construction) filters.
2) Use your filters, if any, under appropriate conditions to obtain their benefits/effects without unintended results, such as flare and ghosting. Otherwise, get creative with the artifacts that occur!

The attached image was shot in 2006 with my old N***n, with a Hoya UV filter; the resulting effect isn't ghosting, but a flare resulting from the placement of the sun at the ridgeline interacting with the glass surfaces of the lens and the filter. The flare was not visible in the viewfinder at the time but was anticipated and incorporated into the design of the shot. Note that the surrounding forest is dead (from a 1995 fire); the flare emphasizes the pair of living trees (alongside the Snow Lakes trail) that survived the fire.
Attached Images
 

Last edited by christinelandon; 06-22-2008 at 03:44 PM. Reason: added image and comment
06-21-2008, 03:53 PM   #26
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QuoteOriginally posted by rburgoss Quote
Has anyone noticed similar results?

RB
Yes.

I took some moonshots on tuesday with my DA 50-200 at 200 at night. The lens had a Tiffen UV filter on it.

Nearly all the shots came out with two moons - one white, and another green shadow, of varying brightness.

And I couldn't see the shadow in the viewfinder. I only noticed on my computer.

A couple days later I took off the filter and shot the moon again, and no longer got any

I no longer have the bad shots so I can't attach them.
06-21-2008, 03:59 PM   #27
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Tiffen filters are just ordinary filters and will exhibit the flare.
06-21-2008, 05:30 PM   #28
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This effect may be real, it may not, and my inclination is to believe that it is ... but unless

- the camera is on a tripod, so
- the camera is not moved
- and nothing is changed except unscrewing the filter,

... these 'tests' prove little.

None of the pairs of photos exhibiting this effect are actually framed the same.
06-22-2008, 07:50 AM   #29
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QuoteOriginally posted by ChrisA Quote
This effect may be real, it may not, and my inclination is to believe that it is ... but unless

- the camera is on a tripod, so
- the camera is not moved
- and nothing is changed except unscrewing the filter,

... these 'tests' prove little.

None of the pairs of photos exhibiting this effect are actually framed the same.
In fact, they do prove that the use of filters, under "dark with bright spots" situation, produces ghosts of such bright spots. With the use of a tripod, such conditions will not change. Of course, the "slight" angle difference between shots (by not using tripod) will make no difference.

If my tests were focused on "where in the picture" or "at which angle in relation to the bright spot" the ghosting happens, of course, I would use a tripod.

Basically, the test as done, proves the only claimed point: Filters do create ghosts under such conditions.

Next test in a logical sequence, it would be to test different filter brands (coatings) to find out if such coatings do work.

RB
06-23-2008, 11:41 AM   #30
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QuoteOriginally posted by ChrisA Quote
This effect may be real, it may not, and my inclination is to believe that it is ... but unless

- the camera is on a tripod, so
- the camera is not moved
- and nothing is changed except unscrewing the filter,

... these 'tests' prove little.

None of the pairs of photos exhibiting this effect are actually framed the same.
Chris, filters on a lens will produce ghosts under the situations appearing in the original photo. You can have the most SMC'd lens and filter, it doesn't matter, the ghosting will happen. I thought this was a well-known fact, but apparently it isn't.
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