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Thread: Need help: MM & IR

  1. #1
    Senior Member rayyen's Avatar
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    Need help: MM & IR

    Need help:
    I'm using my MM with a newly bought IR850...
    Can anyone tell me what's wrong?
    Most grateful.

    Ray


    MM, 21 Elmarit ASPH, f8, 2min
    Leica | Angenieux | Alpa | Hasselblad | Phase One
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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR



    without IR filter, appears perfectly normal.
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    Senior Member JohnBrew's Avatar
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    Re: Need help: MM & IR

    Ray, several things come to mind. At the top you have filter induced flare, but with the lower right and it's severe vignetting it almost appears as if the filter is cocked crookedly on the lens. I'm sure you wouldn't make a mistake like that so it must be the filter isn't seated in it's housing correctly. I'd return it for another brand of filter. Personally, I only use B+W filters.
    A second thought is you might check whether or not your current filter is MRC also.
    Hope this helps.

    Hmm. On second thought I checked all my filters and they are all MRC EXCEPT my IR so maybe I am barking up the wrong tree on that one.
    Last edited by JohnBrew; 14th August 2014 at 04:46. Reason: addition

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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    Thanks John, my friend also suspect that might due to filter's internal reflection, lack of coating... but IR filter, do they have coating... I really not sure, I'll give B+W a try anyway.
    Thanks again! Ray
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    Senior Member segedi's Avatar
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    Re: Need help: MM & IR

    The unfiltered photo looks great!

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    Senior Member segedi's Avatar
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    Re: Need help: MM & IR

    I'd try a few things, same filter, but different lens (if possible) and same filter / same lens, but a much shorter exposure and same filter / same lens but different apertures. This should help narrow things down - if all images suffer, then it probably is the filter. If not, it may be the lens with internal reflection either due to design or aperture etc. Or a combination with the long exposure. What ISO was the affected image shot at?

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    Re: Need help: MM & IR

    This is a now well known light leak problem with long exposures. It isn't just your MM but also the M9 and M240, and the very long exposures from using an IR filter make it even worse. It has also been seen in the past with film M's and long exposures, but of course the recent fashion for 'ten stoppers' etc. is more recent and brought the issue back to the fore.

    There is a long thread on LUF which chronicles it and I've had it myself on all three cameras using a 'ten stopper' or IR filter with exposures over say 30 seconds, but the ambient light does make a small difference.

    The leak is around the area where the lens has the cutout in the lens flange for the focus arm to fit, so top left looking at the camera means bottom right on your image. You can even see the curve of the cutout in the lens flange on your image.

    The solution is simple, given there is no other option, Leica can't fix anything. And the solution is.......a hair scrunchy, the sort of fabric and elastic band thing that women use to bunch their hair up (I'm sure there is a more technical description possible than that). Put it around the base of the lens against the camera body and bingo no light leak, especially if you shade the area above the rangefinder window as well.

    Steve

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    Senior Member JohnBrew's Avatar
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    Re: Need help: MM & IR

    Steve nailed it. I hadn't noticed the IR image was a two minute exposure.

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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    Yes, the exposure was over 2 min.
    Thanks Steve, I'll try your method!!
    Thanks Segedi!!
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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    Steve, do you mind show me quick photo how exactly you tide elastic band on the base of the lens? I don't want to do something stupid and scratch the CCD...
    Many thanks!
    Ray
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    Re: Need help: MM & IR

    Ray, I think the hair band goes around the outside of the lens, externally, where the lens meets the body.
    Ed

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    Re: Need help: MM & IR

    Yes, just focus and then slip it over the lens when you want to make the exposure. You may need to momentarily take the lens hood off to get it over the lens, but it doesn't slow things down too much given you are going to be waiting two minutes anyway.

    It doesn't need to be a hair band, invent something else, but on LUF it seemed like cheap and available solution.

    Steve

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    Re: Need help: MM & IR

    i'd stop way down without the IR filter and try a long exposure; see if the problem remains

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    Re: Need help: MM & IR

    It remains, the leak is behind the aperture blades and is nothing to do with the filter, the f/stop, the ISO, flare from the sun, etc. but the length of the exposure.

    Steve

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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    Thanks guys!!! I'll test it again tomorrow morning

    Ray
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    Re: Need help: MM & IR

    The problem also is that you are using an IR filter that is unsuitable for the camera. As it passes IR in a band for which the sensor is well filtered, you will need extremely long exposures.
    If you use a 092 (B&W numbering) filter your results will not only look better, you will even be able to use the camera handheld if you up the ISO a bit.
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    Re: Need help: MM & IR

    Quote Originally Posted by jaapv View Post
    The problem also is that you are using an IR filter that is unsuitable for the camera. As it passes IR in a band for which the sensor is well filtered, you will need extremely long exposures.
    If you use a 092 (B&W numbering) filter your results will not only look better, you will even be able to use the camera handheld if you up the ISO a bit.
    A good point. I use a Heliopan RG715 that gives a full IR effect on the MM and at a useful decrease in exposure compared to the OP's 850.

    Steve

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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    I tried again with rubber band tie on my ASPH lens, it helps but appears couldn't prevent all light leak...
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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    I've read reviews on internet.
    Some people recommend B+W 093 (true IR block) instead of 092 (which is a dark red),
    any experience share.

    When I switch back to Hoya R72, exposure time cut from 3min to 3 sec, it helps a lot, but it didn't create the kind of white leaf effect like IR850...

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    Subscriber Member jaapv's Avatar
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    Re: Need help: MM & IR

    If you want to use an 093 you are better off with an M8, which is a considerably more effective IR camera than the MM or M9. The M 240 is slightly more IR sensitive than the M240, so you might get away with a 093 there as well.
    The M8 blocks 50% of IR light, the M240 80 % and the M240 at a guess about 70-75%.
    The further you get into IR, the more effective the filtering.
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    Re: Need help: MM & IR

    You can certainly do near IR through a sensor that has an IR cut filter. I would put an something that is opaque to light and IR over your camera and see it the leak is not coming through the body. Black plastic bags aren't that opaque to IR, so you may have to do some testing. It might be coming from the viewfinder/rangefinder

  22. #22
    Subscriber Member jaapv's Avatar
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    Re: Need help: MM & IR

    The effect is caused by visible light leaking around the bayonet flange.It has been documented since the M3.
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    Re: Need help: MM & IR

    Quote Originally Posted by rayyen View Post
    I tried again with rubber band tie on my ASPH lens, it helps but appears couldn't prevent all light leak...
    You need something with more volume and more substantial than a thin rubber band. If you can't find the right sort of hair band drape a cloth around the lens and over the mount.

    Steve
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    Likes 1 Member(s) liked this post

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    Senior Member rayyen's Avatar
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    Re: Need help: MM & IR

    Thanks Steve, I'll try that over the weekend.
    Cheers,
    Ray
    Leica | Angenieux | Alpa | Hasselblad | Phase One
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