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  1. #11

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    Quote Originally Posted by keithwms View Post
    Also, my religion is that you can probably get by with uncoated filters on the the rear element.
    Not really. A filter adds two reflecting surfaces, no matter where they are.


    The biggest filter you may ever need approach does work (financially too), if you get a big one that - with cheap adapters - can be used on all of your lenses.
    In the end cheaper than getting a filter for each filter size your lenses need.
    Unless, of course, if your (other) lenses all share one and the same size.

    A problem with a big filter and step up rings is that it is unlikely that you will be able to attach a good shade.

  2. #12

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    A 77mm hoya or whatever polarizer won't vignette on on a 50mm. I sometimes use a 77mm glass polarizer then a Lee wide angle adaptor with a 100mm ND grad on the front of that and it still doesn't vignette on the 50mm.

  3. #13
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    Quote Originally Posted by Q.G. View Post
    Not really. A filter adds two reflecting surfaces, no matter where they are.
    While it's (trivially) true that a filter always adds two reflecting surfaces, it is incorrect to imply that the situation is as bad for an internal or back filter as for a front filter. By the time the light comes through the aperture it is quite well collimated. Moreover, if you just think about the total amount of direct and stray light reaching the filter, it is clearly far less an issue for internal and back filters. My own evidence is that even inexpensive, uncoated filters work dandily on the back. People do need to find their own evidence of course.

    <end of side track on this thread>
    "Only dead fish follow the stream"

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  4. #14

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    I don't know ...

    A glass surface reflects light. All that it needs is light hitting it.
    If the last surface, it will reflect light back to the surfaces in front of it, which reflect it again to ... It just gets worse, no matter where the filter is.

    The light may be collimated (it isn't) but that doesn't matter much. Just consider that all the surfaces that are in front of it, all the surfaces the light it reflects is bounced off again, are curved.
    It will bounce around in all directions imaginable.

    The light reaching the last glass element in a lens is very strong, compared to the light that reaches the film. In fact, it's just about at the same level, right?

    So i don't see anything to convince me that it would be less a problem if the filter is behind the lens. The position matters very little, if at all.
    That's not just trivially true.

  5. #15
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    Apertures collimate. That's what they do. Moreover, the lens barrel and hood in front of an interior or back filter also greatly reduces the solid angle of (stray) light reaching the filter. This is why sensible people use hoods, especially when they use a front filter.

    So, filter position most certainly does affect the likelihood of artifacts. Whether you can see that or not really doesn't affect my conclusions because I have done my own experiments... as everyone should.

    This discussion is also off topic and I will not entertain it further.
    "Only dead fish follow the stream"

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  6. #16

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    Quote Originally Posted by keithwms View Post
    Apertures collimate. That's what they do.
    And the glass in front of it and behind it bend the light.
    Etc.

    But i guess you're right in that this is going nowhere.

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