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  1. #1
    Join Date
    Feb 2006
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    Question Naked or filtered ... which works better

    I have performed this test with the CZ 135mm f/1.8 ... and found its autofocus deeply affected, close-up, on the wide aperture. Using Manual Focus, the UV-filter had no effect. I was able to achieve a sharp, accurate center-of-focus (or spot-focus) on my subject.

    The autofocus center-of-focus (f/2.5) shifted 1-3mm further back, directly caused by the addition of a relatively decent UV-filter. That can be a tremendous mis-focus, when you are going for sharpness and especially with a lens you paid over a grand for. Like I previously mentioned, manually focused, with the UV-filter on, I was able to get a sharp focus at the COF. Immediately switching back to AF ... it drifted back off to the 3mm displacement.


    Solution: Obviously, shoot NAKED! Yep, remove the filter when you are ready to shoot with AF ... and your focus should be right on the mark. Mine has shifted to precisely where it should be.

    The reason for this test was because it was suggested to me that I should try using my CZ 135mm f/1.8 in my remote bird shots. Well, as you can imagine, protecting the lens from damage is an important aspect of such an effort. The animals certainly have no respect for the costs involved and having squirrels crawling all over the equipment is to be expected. The weather, too, plays a major role, as we are having rain and wind storms every other day. Using a UV-filter in a prophylactic role seems only prudent ... but, it is screwing up the focus to such a degree, the 135mm is not performing any better than 70-300mm f/4-5.6 on a bad day. I would have gained nothing by risking it.

    But, as risky as it is, the reality of it is far worse. If I want to enjoy the power of this lens ... to hell with the filters.

    Just thought I'd share, just in case you wonder what happens shooting through UV-filters. I have personally found that lower-end lenses seem to be more tolerant of the UV-filters. The cheaper the lens, the cheaper the UV can be. Or ... the more expensive the lens ... the less protection you can provide it. Although, there is a limit to that, also. It is like having an extremely sharp scalpel ... it does not take much to dull its edge. If it is a butter-knife, who cares?

    Many will argue that putting a $50 filter on a $75 lens is silly. I would tend to agree and that's why you should probably lift your sights a little higher in your expectations. You really should assume that you are probably going to get a better lens, eventually. Within that line of thinking, already having a good UV or polarizer should be a consideration. If you spend less than $70 for a polarizer-filter (CP), then you have probably goofed up your autofocus to some degree when using it.

    Best way to check is to shoot the length of a yard stick, meter stick or tape measure.
    1. Place your focal target (something 3-D, not flat) along it at some point just past the Minimum Focus Distance (M.F.D.) of your lens. {if your M.F.D. is longer than 3-feet ... just move the yard stick with your focal target, so that you can see the graduations in front and after the focal target}
    2. Take an image (preferably on a tripod) w/o the filter
    3. Without changing the settings or distance, add the filter, refocus and reshoot


    At this point, you should be able to see the difference in image. Heck, shoot it a couple times (w & w/o filter), to repeat results and confirm. It should really open your eyes as to the image quality and impact your UV or CP filter is having on your photography.
    Last edited by DonSchap; 04-02-2009 at 01:32 PM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  2. #2
    Join Date
    Dec 2006
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    God's Country - Australia
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    interesting case, i cant speak for the effect on the sony AF system which according to your example is put out by the additional glass. from my experiecne i've never had a problem with either AF or IQ from using B+W UV filters which are fitted to all my lens'.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
    flickr

  3. #3
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    Cool The cost of doing photography ...

    'Rooz' - You just might want to make a slight mention that B+W CP-filters (not Linear) are about the MOST expensive available to the young photographers (even some older ones). A quick scan of prices and sizes is easily done at B&H ... and if this is the case, you can easily add another $100-$300 to your lens purchase. Again, depending on the optical quality of your lens ... you need to balance that on your "glass appreciation budget."

    Also, once you close down your aperture to f/4 or more ... who cares? It becomes a moot point.
    Last edited by DonSchap; 04-02-2009 at 02:53 PM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  4. #4
    Join Date
    Dec 2004
    Location
    Charleston, SC
    Posts
    2,364
    I've noticed that the Tiffen UV filter that came on my most recent lens caused it to jump focus back and forth.
    I removed it and replaced it with a B&W and have no issues.
    US Navy--Hooyah!

    Nikon D700/D300|17-35 f/2.8, 24-70 f/2.8, Sigmalux, 80-200 f/2.8, 16 f/2.8 fisheye,

    Lots of flashes and Honl gear.

  5. #5
    Join Date
    Feb 2006
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    You know ... since this is a bit of aperture issue ... I'm going to keep the UV-filter on the lens ... until I am indoors ... and then shed its skin with the lens cap removal. The lens cap can keep protecting the filter, in my pocket, while I get true focus through the aperture range.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  6. #6
    Join Date
    Jun 2008
    Posts
    2,204
    Quote Originally Posted by TheObiJuan View Post
    I've noticed that the Tiffen UV filter that came on my most recent lens caused it to jump focus back and forth.
    I removed it and replaced it with a B&W and have no issues.
    Might be a Tiffen issue? No problems with a Hoya Pro-1D CPL and UV here.
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

  7. #7
    Join Date
    Feb 2006
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    Des Plaines, IL
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    and that was at f/2.5?
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  8. #8
    Join Date
    Dec 2006
    Location
    God's Country - Australia
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    Quote Originally Posted by DonSchap View Post
    'Rooz' - You just might want to make a slight mention that B+W CP-filters (not Linear) are about the MOST expensive available to the young photographers (even some older ones). A quick scan of prices and sizes is easily done at B&H ... and if this is the case, you can easily add another $100-$300 to your lens purchase. Again, depending on the optical quality of your lens ... you need to balance that on your "glass appreciation budget."

    Also, once you close down your aperture to f/4 or more ... who cares? It becomes a moot point.
    yes they are expensive. you get what you pay for.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
    flickr

  9. #9
    Join Date
    Feb 2006
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    Cool Of course ... money to drop

    Quote Originally Posted by Rooz View Post
    yes they are expensive. you get what you pay for.
    Yes ... and if I had a Carl Zeiss lens for every time I have heard that clever response ... I would be selling them.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  10. #10
    Join Date
    Jun 2008
    Posts
    2,204
    The CZ filters are supposed to match CZ lenses pretty well with the t* coatings, but I think it's quite gimmicky lol
    flickr

    Canon 7D - 5D | 550EX - 430EX II - (2) PW FlexTT5 | 24-105 f4L | 70-200 f2.8L IS | 100 f2.8L IS | 50 f1.8 II

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