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Thread: Using legacy lenses - infinity focus problems

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    Senior Member kevinparis's Avatar
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    Using legacy lenses - infinity focus problems

    OK

    so I have got over my initial ebay fever and have a groaning shelf of lenses and a pile of adapters for my 510.

    Now my problems begin ... it is spring and I am venturing outside and I am finding that some of my lenses are really struggling to focus.

    The nikons and the OMs seem good, and the contax is fine too - but my M42 takumars seem to lose interest in focusing beyond a couple of feet.

    anybody have recommendations on good adaptors - of course i went for the cheap and simple - but i refuse to pay a mark up to Joe photo in boise idaho for selling me the same stuff i can get on ebay.

    cheers

    Kevin

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    Re: Using legacy lenses - infinity focus problems

    I think you're in a self-contradicting situation: if you get the cheapest possible adapters off eBay, you're taking a higher risk and incurring more inconvenience if you have to return/exchange something. If Joe Photo is worth his markup, he'll prevent or solve such problems with less inconvenience to you, but then you're having to pay more. You pick...

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    Senior Member kevinparis's Avatar
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    Re: Using legacy lenses - infinity focus problems

    point taken regarding you get what you pay for.

    I am just curious to how critical these tolerences are ...are we talking milimeters or fractions of a millimetre being the difference between infinity focus and no infinity focus.

    the cost of manufacture of these things must be low - they are not complex devices - making a good one will not be four or five times making a bad one. Its ironic that I am having trouble with what should be the simplest mount

    I accept Joe photo needs to make his mark up - but i am sure he is sourcing from the same chinese plants.

    apologies to any genuine Joe photo organisation out there - just using that name to make a point

    any recommendations of good sources for an m42 to 4/3 adaptor would be appreciated

    cheers

    K

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    Re: Using legacy lenses - infinity focus problems

    Quote Originally Posted by kevinparis View Post
    point taken regarding you get what you pay for.

    I am just curious to how critical these tolerences are ...are we talking milimeters or fractions of a millimetre being the difference between infinity focus and no infinity focus.

    the cost of manufacture of these things must be low - they are not complex devices - making a good one will not be four or five times making a bad one. Its ironic that I am having trouble with what should be the simplest mount

    I accept Joe photo needs to make his mark up - but i am sure he is sourcing from the same chinese plants.

    apologies to any genuine Joe photo organisation out there - just using that name to make a point

    any recommendations of good sources for an m42 to 4/3 adaptor would be appreciated

    cheers

    K
    See my post below about Zeiss lenses. I was unable to achieve infinity focus using the CQ adapter, but the Milich adapter worked. Difference in thickness between these two adapters is about 0.12 mm.

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    Senior Member kevinparis's Avatar
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    Re: Using legacy lenses - infinity focus problems

    thanks scho
    -interesting to know that the tolerances are that tight

    K

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    Re: Using legacy lenses - infinity focus problems

    Quote Originally Posted by kevinparis View Post
    I am just curious to how critical these tolerences are ...are we talking milimeters or fractions of a millimetre being the difference between infinity focus and no infinity focus.
    We're talking fractions -- small fractions -- of a millimeter.

    I had one M adapter for 4/3 that clearly wouldn't reach infinity; I measured it against a known-good adapter with a dial caliper and found that it was off by 0.08 (eight-hundredths) of a millimeter.

    I've bought independently-made screw-to-M adapters that were too thick by a matter of 0.02 - 0.05mm, which was enough to cause a visible infinity "miss" with a rangefinder camera.

    To use these adapters I thinned them down by rubbing them against fine abrasive paper held on a flat surface. In most cases I could get them down to the correct value (0.98-0.99mm) by removing the chrome finish on the front flange, revealing the brass underneath.

    This made me suspect that the subcontractor who had made the brass adapter had machined it to the nominal thickness -- rather than allowing for the additional thickness of the chrome plating, which might well have been done by a different subcontractor. So that can be all it takes -- the difference between unplated and plated metal.

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