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02-07-2010, 08:35 AM   #1
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Filter or no filter ?

It is my common practice to have a good UV filter (mostly B+W, and a couple of Hoya) mounted on my lenses.

To me, the big plus is lens protection and sparing the lens from repeated dust cleaning

However :
1) will this contribute to some image refractions/chromatic aberration/other problems (?...) especially on the picture edges ?

2) do you see a difference in image quality/definition with or without filter ? What focal lenses would be more deteriorated (if true) ?

3) Given the enhanced glass coating on the DA* lenses, if no filter used, is dust accumulation a problem ?

What is your experience and opinion about this ?

Ed

02-07-2010, 09:11 AM   #2
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There are so, so many threads about this that you can find here if you utilize the search function. But I will still answer your itemized questions:

1) No
2) No
3) Yes
02-07-2010, 10:55 AM   #3
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Nice, but I'll answer them *correctly*:

1. Yes, but not in all situations, and some people's eyes aren't good enough to spot the differences even when they do occur. Better filters means less degradation.

2. Yes, in some situations it is completely and painfully obvious even at web resolution; in others more subtle and only noticeable when comparing at 100%, and in others I dn't see any difference.

3. Never used a DA*, but dust isn't a problem on other lenses, can't see why it would on DA*.

Beyond that, I second the recommendation to please browse/search these forums, as this has been discussed hundreds of times already. I'm moving this to the Beginner's forum.
02-07-2010, 12:52 PM   #4
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QuoteOriginally posted by EdB Quote
It is my common practice to have a good UV filter (mostly B+W, and a couple of Hoya) mounted on my lenses.

To me, the big plus is lens protection and sparing the lens from repeated dust cleaning
Dust, as I write further below, is not a real problem in 95 % of all shooting situations, but reflections are. There are a few shooting envirinments, where protective filters do make sense, especially near salt water, where salt water spray may end up on your lens and that is a sticky stuff. Also wind, together with sand can be dangerous to a glass surface and then protection makes sense. But otherwise, against simple mechanical bumps, a good lens hood offers usually enough protection.

However :
QuoteOriginally posted by EdB Quote
1) will this contribute to some image refractions/chromatic aberration/other problems (?...) especially on the picture edges ?
You will see more flare and ghosting and thus a reduction in contrast when you use filters, if you shoot anywhere near a light source. This is especially pronounced near the sun, or when specular highlights are within the image frame. Also, I have had significant flaring and loss of contrast, with flash outside of the fielf od view but aimed at my subject. Even a good lens hood would not prevent that.

With good filters, what I never have been able to detect was a loss in resolution.

QuoteOriginally posted by EdB Quote
2) do you see a difference in image quality/definition with or without filter ? What focal lenses would be more deteriorated (if true) ?
I used to say in the past, that wide-able lenses would be more prone to unwanted reflections by the filters due to their more curved front surface. But concerete experience shows, that even a short tele will suffer. So, I do not think, that in practice the focal length of the lens is relevant. Relevant is only the amount of the flare/ghosting/unwanted reflection compared to the amount of the light from the subject.


QuoteOriginally posted by EdB Quote
3) Given the enhanced glass coating on the DA* lenses, if no filter used, is dust accumulation a problem ?
Dust accumulation is hardly ever a real problem with lenses, unless you shhot in windy and dusty environments (beach, desert etc.) A few dust specs on the lens will do nothing to either the lens nor the final image. A lot of dust will deterioate contrast when shooting against a bright background etc. But usually some blows with a Rocket Blower or a very light use of a dedicated lens brush will remedy that without scratching anything.

Ben

02-08-2010, 05:22 PM   #5
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Since you already have filters, my suggestion would be to take identical photos with and without. There is no doubt there is a loss of contrast and resolution when using filters, but if you can't detect those differences, they may not matter to you. There are certain times when it's obviously wise to use a filter (salt spray for example), and times when it's not (bright backlight), so you'd want to test situations that don't fall into those categories.

Paul
02-08-2010, 06:37 PM   #6
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Thank you all, I appreciate your responses
Ed
02-08-2010, 06:50 PM   #7
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2 Filters you must have.

B+W clear filter To protect the lens
B+W circular polarizer to remove reflections of shinny surfaces an add contrast to the sky.

You Most definitely do not need a UV filter. Most people claim they use it to protect there lens. To protect your lens use clear filter. Digital sensors and modern lenses are not sensitive to UV in any way. UV filter will not help protect your lens and can degrade from the quality of your image. Only use UV filter if you have a non digital film camera.

B+W filters can be expensive, but you pay for what you get. Not having a quality filter can degrade from the quality of your image. You don't want to place a cheap piece of glass in front of your high quality lens.
02-09-2010, 03:12 AM   #8
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QuoteOriginally posted by Alex00 Quote
2 Filters you must have.

B+W clear filter To protect the lens
B+W circular polarizer to remove reflections of shinny surfaces an add contrast to the sky.

You Most definitely do not need a UV filter. Most people claim they use it to protect there lens. To protect your lens use clear filter. Digital sensors and modern lenses are not sensitive to UV in any way. UV filter will not help protect your lens and can degrade from the quality of your image. Only use UV filter if you have a non digital film camera.

B+W filters can be expensive, but you pay for what you get. Not having a quality filter can degrade from the quality of your image. You don't want to place a cheap piece of glass in front of your high quality lens.
In how far do UV filters degrade the image more than so calles "protective filters"? I cannot really see a difference.

Filters may degrade the IQ NOT because they filter out a certain part of the spectrum, but because of their surface roughness or the lack of plano-parallel surfaces (cheap filters often have a wedge error). Cheap filters are only "flame polished", which means, heated until the worst surface roughness after cutting the filters, melt down. This leaves an "undulating" surface, which obviously is detrimental to IQ. A good filter (as the B+Ws you mentioned, but also the more expensive Hoyas/Kenkos) are really mechanically polished, which gives a much smoother surface.

Also, UV filters might not be needed for UV filtration under usual photographic circumstances, they can help reduce the secondary spectrum of older lenses. Ref: Legacy Lenses Tamron SP 300mm f2.8 LD IF - Fourthirdsphoto Forum see epsecially the posts of "TamronSP".

This thread has been accompanied by a lot of interesting graphs and measurements, but somehow these are not visible now. May be only, when you are looged-in? Anyway, the discussion quite clearly shows, that for legacy glass, the use of a good UV filter might even be very beneficial.

Ben

02-09-2010, 03:33 AM   #9
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For DSLR's Your front glass is already UV coated. You don't need double UV filtering. This can cause lens flares, difference in IQ - lower contrast, washed out colors and will cause softness in the images. Clear Filter is the way to for protecting your lens.

On the other hand For Film camera go with a UV filter.

Speaking about Hoya Filters. Have you ever tried cleaning one. It's a nightmare. B+W the best around.
02-09-2010, 04:19 AM   #10
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QuoteOriginally posted by Alex00 Quote
For DSLR's Your front glass is already UV coated. You don't need double UV filtering. This can cause lens flares, difference in IQ - lower contrast, washed out colors and will cause softness in the images. Clear Filter is the way to for protecting your lens.

On the other hand For Film camera go with a UV filter.

Speaking about Hoya Filters. Have you ever tried cleaning one. It's a nightmare. B+W the best around.
Sorry, your statements seem a bit short on facts to me. It is clear, that ANY filter on a lens can cause flareing and ghosting and added reflections. But I cannot see, why a so called "protection" filter would cause less of these problems than a UV filter?

Anyway, all lens elements are acting to a degree as UV filters, as plain glass already filters out UV to some extend.

Don't misunderstand me: I do not recommend, that UV filters should be used as lens protection under each and any circumstance. I can see (as I wrote in my other posts), some well-defined situations (beach, sea shore, desert etc.), where lens protection makes sense. And whether that be done with a "protective" filter or a UV filter seems to me quite pointless, because both types will provide the same problems.

Furthermore in excess UV environments, like very high altidtude, snowy mountains, very clear skies at the sea etc., a UV filter will cut down this excess UV and thus prevent added reflections inside a lens and a loss of sharpness and contrast, as basically no lens is computed to focus the deep blues (except those rare UV lenses like the old Takumar Ultra-Achromat).

For filter brands: I can see a point for B+W and I can see a point for other high grade filters. I use both, B+W (Pols and UVs) and Hoya/Kenko (Pols and UV) and have not experienced problems with any of them. Yes, I have cleaned my Pro Digital 1 filters as well.

Ben
02-09-2010, 11:58 AM   #11
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The questions is why would you put a UV filter i your DSLR sensor is already equipped to remove UV light. Why the redundancy. UV filters may be useful at high altitude where there is a lot of UV but at lower altitude image look less "warm".

There are many articles and examples at dpreview that shows before and after with uv filters.
Have you tried holding up a b+w clear filter to the light. You can't even tell there is a glass in there.

Last edited by Alex00; 02-09-2010 at 12:40 PM.
02-09-2010, 02:04 PM   #12
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QuoteOriginally posted by Alex00 Quote
The questions is why would you put a UV filter i your DSLR sensor is already equipped to remove UV light. Why the redundancy. UV filters may be useful at high altitude where there is a lot of UV but at lower altitude image look less "warm".

There are many articles and examples at dpreview that shows before and after with uv filters.
Have you tried holding up a b+w clear filter to the light. You can't even tell there is a glass in there.
That's not my question. You wrote:

"For DSLR's Your front glass is already UV coated. You don't need double UV filtering. This can cause lens flares, difference in IQ - lower contrast, washed out colors and will cause softness in the images. Clear Filter is the way to for protecting your lens."

So, how would a clear filter lead to less IQ degradation than a UV filter? I simply do not understand your argument here and I would be grateful for an explanation. Thanks!

Ben
02-09-2010, 02:20 PM   #13
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I always always buy filters for my lenses. It not only helps prevent accidental damage, but also prevent water from anywhere from splattering the front element, it also reduces the amount of dust that could get inside. But to me it's not the water or accidental damage, it's all about minimalizing dust that can get inside. I actually just ordered a Kenko 67mm MC UV filter for only 15 bucks just 10 minutes ago.
02-09-2010, 02:38 PM   #14
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Both the DSLR sensor and and uv coating the lens block UV light. You don't need to throw in yet another UV filter on top. If you google this UV filter image quality topic you will find an overwhelming number of sites talking about image quality and softness using UV filters.

Should you use a UV filter on your lenses ? - Photo.net Casual Photo Conversations Forum
UV Filter causing soft images.: Canon SLR Lens Talk Forum: Digital Photography Review

B+W clear filter offers the World's best optical glass, Highest possible polishiing technique and no degradation, veginating, softining of your photos. I was honestly surprised when i couldn't tell there there is a glass inside the ring. I even put the filter up to the light and i took me a while to see it. That's what i call quality. The filter will not degrade quality or change speed of the lens and stated by B+W and from my experience using the filter. The Multi Resistiant Coating reduces moisture, dust, and other dirt particles, as well as significantly increases the scratch resistance of its surface.

Lastly, Using common sense it makes more sense to to use clear filter since a UV filter is not needed.
02-09-2010, 02:41 PM   #15
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QuoteOriginally posted by LeDave Quote
I always always buy filters for my lenses. It not only helps prevent accidental damage, but also prevent water from anywhere from splattering the front element, it also reduces the amount of dust that could get inside. But to me it's not the water or accidental damage, it's all about minimalizing dust that can get inside. I actually just ordered a Kenko 67mm MC UV filter for only 15 bucks just 10 minutes ago.
Dust simply does not get into a lens through the front element. This is really one thing, where a filter does not do any good at all.

Ben
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