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  1. #1
    hdeyong's Avatar
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    Light meters in the dark

    I have a couple of Olympus OM's that I use all the time, and they're always kept in a bag. Just a habit I got into long ago, when I realized I couldn't stand a camera hanging around my neck. Plus, the protection, etc.
    Anyway, sometimes I forget to turn the camera off, (for several days at a time), and it doesn't seem to affect battery life.
    So, my question is, if the light meter has nothing to meter, is there little or no battery drain?

  2. #2

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    confirmed e. g. the Rolli 35T slip case is like a changing bag saves cost of switch

    but Pentax K1000 and earlier spots have a auto
    light sensitive switch to reduce residual to zero in near dark

    no way of telling how good your bag is...

    so undesirable unless bag is light tight and you use caps switch off & affix cap before sticking in bag

    the OM1 sensors can detect light leaking from eye piece

    you need to be using silver or air battery for 1/3 of a stop accuracy.., the Pentaxs can use any battery with some life left, they have a balanced bridge circuit

    OM are nicer though... furtively hides awaiting wrath

    but if you are using om2 leave them off all the time they only need to be on if the shutter is slower than 1/30 they will meter off the film ok in auto when speed faster than 1/30

    The other OMs are automatic but you need to down load the manual.
    Last edited by Xmas; 09-24-2013 at 12:33 AM. Click to view previous post history.

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    Both my OM10 and OM2 can stay on for days without any problem! In the end though, you just have to change battery earlier than you would if it would have stayed of.. My OM10 hasn't had a new battery since March 2012, and it still works like a charm after all the times I forgot to turn it of or it accidentally got turned on when carrying it.

  4. #4

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    Quote Originally Posted by McErland View Post
    Both my OM10 and OM2 can stay on for days without any problem! In the end though, you just have to change battery earlier than you would if it would have stayed of.. My OM10 hasn't had a new battery since March 2012, and it still works like a charm after all the times I forgot to turn it of or it accidentally got turned on when carrying it.
    An OM10 goes into a low battery drain condition after 90 seconds unless it is in a tight fitting g bag, and the first pressure tripped repeatedly, if you carry a OM1 all day with cap off and switched on in good light it uses battery all day.

    You don't need to turn an OM2 on if you know the shutter speed is going to be more than 1/30. It does an OTF and 1st blind pattern exposure reading even when switched off doing an ok exposure from 1/1000 to1/30.

    I never turned my OM2 on or replaced batteries.
    Don't think you need to turn on an OM10 either just hit the shutter for good exposure.

  5. #5
    Peltigera's Avatar
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    There is no need to turn on the OM 10 so long as you are happy with the camera selecting the shutter speed. Mostly I am, but if the light is not too good, it might select a shutter speed a tad too slow without you realising it.

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    Thanks for the confirmation.
    but if you leave it off and drop it back in gbag it won't have to worry about how dark it is if there are loose articles in with it tripping the first pressure.
    The OM10 and OM2 real clever.

  7. #7

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    Quote Originally Posted by hdeyong View Post
    I have a couple of Olympus OM's that I use all the time, and they're always kept in a bag. Just a habit I got into long ago, when I realized I couldn't stand a camera hanging around my neck. Plus, the protection, etc.
    Anyway, sometimes I forget to turn the camera off, (for several days at a time), and it doesn't seem to affect battery life.
    So, my question is, if the light meter has nothing to meter, is there little or no battery drain?
    The photocells in a meter circuit have very high resistance in the dark, as the light level increases the resistance falls - this is how meters work.
    Depending on the type of cell, the resistance can be on the order of megohms when no light is falling on it.

  8. #8
    hdeyong's Avatar
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    That makes sense. Thanks E.

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    It would be true for cameras like the OM but for modern cameras like a Nikon F5 for example, if the meter doesn't time out and shut itself off it would draw about the same current even with the lens cap closed.

  10. #10

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    true but each of the OMs are different.
    a simple CdS cell draws no current in a changing bag but a off on switch is desirable as they will work (draw current) in overcast moonlight even if the meter or coupling does not register it.
    Only the OM1n and OM1 have a CdS cell.
    The other OMs have photocells which react more quickly for offthe film or shutter curtain metering and spot metering depending on model.
    I normally omit the battery from my OM1s.
    Unnecessary complication, bit like a phone in pocket really.
    Though with an F5 you can show people you have not taken their photo.
    hee hee hee

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