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Thread: M8: How does it know what F stop Im using?

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    Senior Member dude163's Avatar
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    M8: How does it know what F stop Im using?

    The camera is magic!!


    how does it detect what f stop I am using, even though the lenses are manual?

    Is it some light detection algorithm? or a mechanical connection between the lens and camera?

    Thanks

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    Re: M8: How does it know what F stop Im using?

    Quote Originally Posted by dude163 View Post
    The camera is magic!!


    how does it detect what f stop I am using, even though the lenses are manual?

    Is it some light detection algorithm? or a mechanical connection between the lens and camera?

    Thanks
    It makes an educated guess . . . good though!

    Just this guy you know

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    Senior Member dude163's Avatar
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    Re: M8: How does it know what F stop Im using?

    I agree

    look atthis

    http://www.flickr.com/photos/rivervi...61784732/meta/

    its 100% correct! and when i was using f2.8 and f2 it was correct then also

    LEICA!!!

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    Re: M8: How does it know what F stop Im using?

    If you look at the front of the camera, there is a small bluish dot to the upper left of the Leica red dot. This is a secondary light meter. It takes an EV reading then compares the current shot's ISO and shutter speed to calculate the aperture. While not 100% accurate due to the reading not being through the lens (TTL), it is usually within a stop of the actual aperture.

    David
    David Farkas
    Leica Store Miami

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    Senior Member Per Ofverbeck's Avatar
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    Re: M8: How does it know what F stop Im using?

    Quote Originally Posted by dude163 View Post
    ....how does it detect what f stop I am using, even though the lenses are manual?...
    One might say the M8 (and the M9) has two exposure meters. One measures light through the lens, and thatīs the one that actually determines exposure times in Auto, or generates the readouts in Manual.

    The other, simplified one has its cell in the little round window just beside the Leica īred dotī. It measures light falling directly on the front, and so has no idea of the f/stop set on the lens, but the coding on the lens (or the manual lens setting) tells it the maximum aperture (it also probably helps in setting auto white balance, but thatīs another thing).

    So, the difference in reading is assumed to depend on how much the lens is really stopped down, and thus the f/stop setting can be computed.

    But, just as an old-fashioned MR meter with external cell is usually less accurate than a TTL meter (influenced by stray light outside the image field & c), this comparison doesnīt give exact results.

    Edit: Dave beat me to it, just when I was writing....

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    Member HenryFool's Avatar
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    Re: M8: How does it know what F stop Im using?

    That's pretty cool, it's not working for me though...

    http://www.flickr.com/photos/henryfool/5531809378/meta/

    I'm guessing that the lens has to be coded for this to work???
    Last edited by HenryFool; 28th March 2011 at 03:09.

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    Senior Member dude163's Avatar
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    Re: M8: How does it know what F stop Im using?

    I dont think it has to be coded as my cron is from 1964

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    Re: M8: How does it know what F stop Im using?

    I'm guessing that the lens has to be coded for this to work???
    For focal length and max aperture data, yes, you need to be using a 6-bit coded lens on the M8. The M9 has an option to manually select the lens from a menu.

    LR and C1 display aperture info. I don't think Aperture reads and displays this info (a little ironic, actually). Any Aperture users want to chime in here?

    David
    David Farkas
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    Re: M8: How does it know what F stop Im using?

    Quote Originally Posted by dfarkas View Post
    I don't think Aperture reads and displays this info (a little ironic, actually)
    LOL

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    Re: M8: How does it know what F stop Im using?

    Unfortunately, this system doesn't work very well when using a strong ND filter. I guess that makes sense though, there's no way for the camera to know what you're putting in front of the lens, and obviously a lot less light is getting through.

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    Re: M8: How does it know what F stop Im using?

    Quote Originally Posted by dfarkas View Post
    LR and C1 display aperture info. I don't think Aperture reads and displays this info (a little ironic, actually). Any Aperture users want to chime in here?

    David
    its true, Aperture can't display the aperture...
    I was pleasantly surprised when I used C1 and got the aperture info

    Peter

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