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07-30-2012, 01:29 PM   #1
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3 stacked optical filters don't seem to affect IQ

I read on one of the forums where someone said they don't like to use UV filters cause they degrade the image with a layer of glass over the lens. While I'm not in the position to argue against that with lab conditions. I will say using 3 filters of glass over my lens did not seem to hurt IQ one bit.

Some background info...

I did not set out to do this test. Nor did I set out to shot the image with 3 filters on it. I was shooting some landscapes in the cemetery. I had a UV filter on, as I have on almost all my lenses. I also added a polarizer consisting of 2 glass filters. The polarizer was even dusty since I forgot to bring a blower with me. So 3 pieces of glass were in front of a 35mmA 645 lens. When it came time to shoot the gravestone I had forgot that I had the polarizer on it or would have removed it.

Let me apologize to those that are offended by religious symbols. I'm not religious myself. (Well I may be 'religious' about shooting in the cemetery!) So I did not pick the subject matter to do this test on. It caught my eye as an interesting grave stone with the weathering. And only after I saw the results and remembered the 3 filters did I decided to do a writeup on it. And to those of you who are devout in your beliefs...well you get a bonus with the filter test!







Pentax 645D, Pentax 645 35mmA lens. Top image has been cropped about 15-20% Hand held, no mirror lockup, no tripod. RAW image was processed as a 0,-1,+1 HDR with 3 images created from 1 RAW file.

The resulting TIFF is much sharper than these reduced JPEGs. But, you can still see the sharpness with 3 filters. Now it may be sharper with no filters. I never shot it wihtout at least 1. But the point here is 3 filters and it is still doable very nicely.


Last edited by slackercruster; 07-30-2012 at 03:57 PM.
07-30-2012, 03:43 PM   #2
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QuoteOriginally posted by slackercruster Quote
I read on one of the forums where someone said they don't like to use UV filters cause they degrade the image with a layer of glass over the lens. While I'm not in the position to argue against that with lab conditions. I will say using 3 filters of glass over my lens did not seem to hurt IQ one bit.

Some background info...

I did not set out to do this test. Nor did I set out to shot the image with 3 filters on it. I was shooting some landscapes in the cemetery. I had a UV filter on, as I have on almost all my lenses. I also added a polarizer consisting of 2 glass filters. The polarizer was even dusty since I forgot to bring a blower with me. So 3 pieces of glass were in front of a 35mmA 645 lens. When it came time to shoot the gravestone I had forgot that I had the polarizer on it or would have removed it.

Let me apologize to those that are offended by religious symbols. I'm not religious myself. (Well I may be 'religious' about shooting in the cemetery!) So I did not pick the subject matter to do this test on. It caught my eye as an interesting grave stone with the weathering. And only after I saw the results and remembered the 3 filters did I decided to do a writeup on it. And to those of you who are devout in your beliefs...well you get a bonus with the filter test!







Pentax 645D, Pentax 645 35mmA lens. Top image has been cropped about 15-20% Hand held, no mirror lockup, no tripod. RAW image was processed as a 0,-1,+1 HDR with 3 images created from 1 RAW file.

The resulting TIFF is much sharper than these reduced JPEGs. But, you can still see the sharpness with 3 filters. I've got a hell of a lot of sharp lenses, I wont complain about this one ...even with 3 filters stacked on it!
Yeah the shoots look good. I have also used (on 35mm) a polarizer and red filter with no IQ issues shooting b&w film.

Phil.
07-30-2012, 04:01 PM   #3
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Not bad! I've never been much for UV filters.

What brand of filters were you using?

I've never notices a IQ difference with my polarizers, although I've never actually done a direct comparison either. My ND8 leaves a crosshatch pattern that is slightly noticeable at 100%.
07-30-2012, 04:23 PM   #4
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Looks good but what would it look like without those filters? One of the lens rental places did a nice article on filters and their negative impact on IQ, much more convincing.

07-30-2012, 06:30 PM   #5
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Okay , so you are happy with these results. Thats good. You dont really need a 645D then. The third example is totally ruined by the filters. Might as well shoot jpg on a point and shoot. And in the second example , the shadowed spider webs in the cross should be visible as spider webs not blobs of hanging dust, but the filters on the lens obliterated the detail I shoot 645D for...
07-30-2012, 09:41 PM   #6
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QuoteOriginally posted by 672 Quote
Okay , so you are happy with these results. Thats good. You dont really need a 645D then. The third example is totally ruined by the filters. Might as well shoot jpg on a point and shoot. And in the second example , the shadowed spider webs in the cross should be visible as spider webs not blobs of hanging dust, but the filters on the lens obliterated the detail I shoot 645D for...
What on Earth are you talking about??? And why the attitude??? Guess what, if you don't want to shoot with filters, don't. But we don't need your condescension. And you do understand that all of these are crops of the same image. One taken handheld.
07-30-2012, 09:54 PM   #7
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I agree with 672--the quality of the pictures are low--and should not be a basis for saying filters don't have a detrimental impact. And the results do look like a P&S camera.

Nevertheless, sure 2 filters are OK if the subject is improved by it. Then you should use them.

But still one strives to have the best quality and filters will degrade resolution, can introduce some curvature of field, and more air-glass interfaces will cause more flare. So the usual recommendation--don't use a filter if you cannot give a good reason for it--is still a good idea. Or more generally do all you reasonably can to get the best technical quality.
07-31-2012, 04:43 AM   #8
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QuoteOriginally posted by JenniferLeigh Quote
Not bad! I've never been much for UV filters.

What brand of filters were you using?

I've never notices a IQ difference with my polarizers, although I've never actually done a direct comparison either. My ND8 leaves a crosshatch pattern that is slightly noticeable at 100%.

Tiffen. And I don't like them that much. I find a good amount of QC issues with them.

07-31-2012, 04:47 AM   #9
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QuoteOriginally posted by Docrwm Quote
Looks good but what would it look like without those filters? One of the lens rental places did a nice article on filters and their negative impact on IQ, much more convincing.

Don't know? Once I get a lens clean and free of dust I never remove the UV unless I have a good reason. I'm not that motivated to remove the UV.

Between JPEG, reducing and photobucket the IQ has been cut a lot. The TIFF's are about double sharp as the ones I posted here. Don't know how to post the TIFF files.
07-31-2012, 04:52 AM   #10
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QuoteOriginally posted by dms Quote
I agree with 672--the quality of the pictures are low--and should not be a basis for saying filters don't have a detrimental impact. And the results do look like a P&S camera.

Nevertheless, sure 2 filters are OK if the subject is improved by it. Then you should use them.

But still one strives to have the best quality and filters will degrade resolution, can introduce some curvature of field, and more air-glass interfaces will cause more flare. So the usual recommendation--don't use a filter if you cannot give a good reason for it--is still a good idea. Or more generally do all you reasonably can to get the best technical quality.

Sure one should not use filters for no reason. I had 3 filters on by mistake. I use a UV all the time for protection and that is about it.

Just saying some togs fear using a filter at all for fear of degradation. As I said the TIFF is much sharper. If you can tell me how to post it I will be glad to.

That would be a good experiment in itself. Showing loss of IQ comparing original to one reduced and hosted by photobucket. I tried to make them as big as I could. But photobucket stalled a few times with just a slightly larger image.

Last edited by slackercruster; 07-31-2012 at 05:08 AM.
07-31-2012, 04:58 AM   #11
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QuoteOriginally posted by 672 Quote
Okay , so you are happy with these results. Thats good. You dont really need a 645D then. The third example is totally ruined by the filters. Might as well shoot jpg on a point and shoot. And in the second example , the shadowed spider webs in the cross should be visible as spider webs not blobs of hanging dust, but the filters on the lens obliterated the detail I shoot 645D for...

Depth of field

Shot fairly wide open. The screws are sharp as hell in the TIFF.

Also, you can't cut a pix down to post here and expect to keep every spec of detail. But what is in focus is very sharp in the original RAW/TIFF.

Last edited by slackercruster; 07-31-2012 at 05:10 AM.
07-31-2012, 05:05 AM   #12
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QuoteOriginally posted by JenniferLeigh Quote
Not bad! I've never been much for UV filters.

What brand of filters were you using?

I've never notices a IQ difference with my polarizers, although I've never actually done a direct comparison either. My ND8 leaves a crosshatch pattern that is slightly noticeable at 100%.

I get my lenses dirty a lot of the time. I like a UV if possible. Rather clean the filter than the lens.

This weekend got some grease spots on the front element at a street fair. No filter allowed on that lens. Took grease off with Q tip and cleaner. Then recleaned with cleaner and lens paper. Wish I was able to use a filter on that lens, but had to make do.

A lady hit my lens with her cane. Didn't hit the glass. But If I had a filter on it and she hit the glass filter may have helped some. I've always used UV or skylight on a lens. Just like to be careful.

Last edited by slackercruster; 07-31-2012 at 05:11 AM.
07-31-2012, 06:21 AM   #13
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QuoteOriginally posted by Yamanobori Quote
What on Earth are you talking about??? And why the attitude??? Guess what, if you don't want to shoot with filters, don't. But we don't need your condescension. And you do understand that all of these are crops of the same image. One taken handheld.
You get all types on the forums. But I don't care. I always like to check into complaints. So I looked at the size reduction from my originals to what ended up here to see if the scoffers have any credibility.

The RAW was about 55mb. I uploaded about 900kb jpeg to photobucket. What came out here was a little over 300kb

What is that? About 1/2 of 1% is left from the original? Plus JPEG destruction? I think it is still fantastic res for a 99.5% loss from the original.

And it is good to have pixel peepers like these guys. I never noticed the spider webs. Too focused on the interesting patina of the metal. The webs could have come out better on a tripod and a small aperture. But anyone can see the DOF is very shallow.

Anyway, let me know how to post the TIFF if you want to see em guys. (gals)

Last edited by slackercruster; 07-31-2012 at 06:30 AM.
07-31-2012, 06:28 AM   #14
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QuoteOriginally posted by slackercruster Quote
I get my lenses dirty a lot of the time. I like a UV if possible. Rather clean the filter than the lens.

This weekend got some grease spots on the front element at a street fair. No filter allowed on that lens. Took grease off with Q tip and cleaner. Then recleaned with cleaner and lens paper. Wish I was able to use a filter on that lens, but had to make do.

A lady hit my lens with her cane. Didn't hit the glass. But If I had a filter on it and she hit the glass filter may have helped some. I've always used UV or skylight on a lens. Just like to be careful.
Those are the reasons that I always use a hood.
07-31-2012, 07:13 AM   #15
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It is possible that i over reacted to slackercrusters images. I apologize. What i meant to say was. I recently ruined four days of shooting in sedona arizona with my 645D. Not having done any testing , i decided the red rock country would be ideal for a polarizer. I shot with 645A 45mm, P67 75mm 2.8, and 645FA 400mm. Every single shot on every single lens with a pola is , to me , useless , except as a web photo, not what i shoot the 645D for.

I used a Moose Petersen warm polarizer in 67mm and a Schneider polarizer in 77mm size. No lens , polarizer, aperture combo looks acceptable for large prints and in some cases not acceptable for small prints.

Also my Cokin Grads in grey or tobacco , which made 67ll film images sing are totally useless on digital....
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