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  1. #1

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    Hand held meter and lens focal length.

    I'll be testing the Minolta SRT-201 today.There are 2 lenses that I will use: #1.50mm 1.7 #2.70-200.
    Will I have to adjust the metering to compensate for the different glass?

    Thanks

  2. #2

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    what will you be shooting?

    my short answer is no. If you were photographing a cat and the meter says f5.6 at 1/125 it will be the same for a 200mm shot as it would be for a 50mm shot.

    The problem is if you shoot the 50mm at the same distance that you shoot it at 200mm the field of view will change. The shot at 50mm will have a bigger field of view and potentially have more variance in the highlight and shadow areas.

    So yes you might have to adjust the exposure for the 50mm shots to make sure the highlights and shadows record enough information.

    Confused yet? I am.

  3. #3
    Rol_Lei Nut's Avatar
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    Better example, if you photograph the cat sitting on a pile of coal in a snowy lanscape:

    With the 200mm, you might only frame the cat itself (presumably close to neutral grey in tone) and so get a "correct" exposure.
    With the 50mm (if you are now taking in the whole scene), you might be getting more or less of the snow or coal in the image, and the camera's meter might be "fooled" by the lighter or darker objects one way or another.
    But with both lenses, if you are careful to only meter the cat, no exposure compensation is needed (the meter should give the same results).

    Also, if the zoom's aperture varies with its focal length, you need to take that into account if using a hand-held meter.
    M6, SL, SL2, R5, P6x7, SL3003, SL35-E, F, F2, FM, FE-2, Varex IIa

  4. #4

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    incident readings will be the same as it doesn't really care about the subject (only what light is hitting the subject)

    however if you take a reflected light reading with the handheld meter. The meter will have it's own 'field of view' (it probably will say in the manual for the meter). So whatever that field of view is will be what is averaged to give you the meter reading.

  5. #5

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    No, this was a question on a recent quiz my students took. Focal length is not a factor in determining exposure (except in micro/marco situation when one must calculate bellows extension).
    When I grow up, I want to be a photographer.

    http://www.walterpcalahan.com/Photography/index.html

  6. #6

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    Thanks all!!

  7. #7

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    My favorite is the Pentax Spot Meter.
    http://photo.net/large-format-photography-forum/00AuDA

  8. #8
    Christopher Walrath's Avatar
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    Yeah, um, no. f/4 is f/4. Just a larger entrance pupil in a longer lens than a shorter one. Ratio of diameter to length remains the same.
    Thank you.
    CWalrath
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  9. #9

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    Last edited by Pumal; 02-21-2010 at 06:45 AM. Click to view previous post history.

  10. #10
    benjiboy's Avatar
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    My experience of using a separate meter with prime lenses and zoom both with daylight and flash(strobe) leads me to believe that there is a significant difference between you're 50mm f1.7 prime lens and you're 80-200 zoom , because apertures are proportions, for example f8 means that the diameter of the front element of the optic divides eight times into the focal length and is no real indication of how much light is passing through the lens,which is why in the film industry zoom lenses use T stops not f stops because they are a true indication of light transmission, so with a 80-200 zoom the light has to possibly go through twelve or more elements before reaching the film I find it's a case of getting to know you're own equipment, and giving a little more exposure with the zoom bases on you're own experience.
    I find that as other members have written that with lenses of different focal lengths because of their different angles of view if you are unable to get close to the subject a spot meter is very useful, but if you don't have one I find that taking an incidental light reading if the subject isn't too far away can do the trick.
    Last edited by benjiboy; 02-21-2010 at 08:42 AM. Click to view previous post history.
    Ben

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