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10-06-2008, 12:47 AM   #16
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depends on lens, with the 50mm 1.2 pentax-a i have, i always get filter ghosting....this unknowingly killed some of my shots..sigh, the 1.2 doesnt have a filter in place, unless it rains/potential problems

but i have a filter on every other lens which has no problem with filter ghosting

10-06-2008, 12:57 AM   #17
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Some of the newer Pentax lenses have the SP coating that protects the exposed lens elements from grease and dust. Another reason to do away with a UV filter.
10-06-2008, 01:36 AM   #18
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QuoteOriginally posted by wlank Quote
...Forget about pixel-peeping. Print the results, display them on you monitor, do whatever you do with pictures...
Pixel peeping is the ONLY way to decide on such maters (lens, camera, filters ).
Any other way you only judge the photographer
My opinion ...
10-06-2008, 04:03 AM   #19
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QuoteOriginally posted by drewdlephone Quote
Just curious, why not compressed air? Thats actually what I have been using, in conjunction with a microfiber cloth, for keeping the glass clean. I've only used microfiber on them once (I somehow got a fingerprint dead center on my filter) and the rest of the time I just check for dust, and use the air can, albeit VERY lightly.
It's simply due to the power of compressed air. A person runs the risk of blowing dust farther back into their lens unless they do as you do and use the canned air carefully.

10-06-2008, 05:26 AM   #20
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QuoteOriginally posted by TaoMaas Quote
It's simply due to the power of compressed air. A person runs the risk of blowing dust farther back into their lens unless they do as you do and use the canned air carefully.
And also the residue, it's NOT just air that comes out, but some propellant as well. Canned air is bad, Ive had bad experiences and Im using the stock I gathered to clean my shaver with now.

For my camera I use a rocket blower and microfibre cloths and nothing else.

Venturi, I feel the exact same.

As for ghosting, Amen to whoever said to remove it for night shots. I have so many photos with streetlamp ghosting in them
10-06-2008, 06:37 AM   #21
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QuoteOriginally posted by drewdlephone Quote
Just curious, why not compressed air? Thats actually what I have been using, in conjunction with a microfiber cloth, for keeping the glass clean. I've only used microfiber on them once (I somehow got a fingerprint dead center on my filter) and the rest of the time I just check for dust, and use the air can, albeit VERY lightly.
There is a theory that canned gas will jump out of its container and ruin whatever it touches. Anecdotes gleaned from the internet abound, but factual cases of damage are rare as gold plated hens teeth.
If you are talking real compressed air, be aware that air compressors build up humidity inside the tank which can spray out the line, and this is made worse if the compressor is an oil type.

I've used canned gas (Dust-Off, specifically) for some 35 years for routine dusting of the insides of cameras with no damage.
I am planning on buying a tank of nitrogen, ostensibly for tire maintenance on my vehicles, but I will likely run a line into the house as well with the intention of using it for camera maintenance.

As an aside, I just did some very extreme macro the other day (bellows and 100mm bellows lens). I didn't bother to blow off the K20 sensor first, and I also didn't see any dust on the sensor, which normally shows up very badly in macro work.
The dust removal on start up seems to do something for dust reduction.
Regarding filters, I wouldn't bother. I haven't used UV filters on lenses for 25 years, and have yet to damage the front of a lens.
I do NOT baby my equipment, either.
A few specks of dust doesn't have the potential to hurt your pictures as much as a filter does.
Personally, I think people get too hung up on keeping their lenses too clean, and that is when they start getting cleaning marks, which really do degrade image quality.
10-07-2008, 11:01 AM   #22
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QuoteOriginally posted by sewebster Quote
Am I correct in assuming that UV filters do nothing useful with regards to actually filtering UV light when used on a digital camera?
I hope not. I am hoping to do some UV photography, I have some 70 year old documents where the writing is unreadable and I was recommended to try UV reflection photography (apparently this is used by forensic scientists). From what I have found on the web, digital cameras are sensitive to UV, but they are more sensitive to IR and visible. The problem is that UV (transmissive) filters also allow IR (ie they block out the visible light between UV and IR) so you have to have an IR blocking filter too. Also, optical glass and multicoatings absorb UV too. The combination of having to get expensive UV filters, IR filters and a UV lens makes the whole process seem too expensive for me. And that is to get UV into the camera! If it is so difficult to get UV into the camera it makes me wonder why anyone is worrying about filtering out UV! :-)

In my searches on UV photography I have come across "cheap" solutions where you are encouraged to polish off the multicoating off your chosen lens (imagine doing that to an smc lens!) or to use a cheap non-coated lens with few optical elements (the single coated Helios 58/2 was suggested on one site.) Or you can modify a flash to produce more UV.

Anyway, here's more about UV photography.

Richard
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