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  1. #1

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    Do different lenses typically expose differently?

    I had always thought that there was supposed to be little to no perceptable difference between different lenses when it came to exposure. In other words, f/8 at 1/250 second with one lens should give the same exposure as f/8 at 1/250 second on another lens. But, for whatever reason, it seems like there is quite a bit of variance between my lenses. For instance, my 50/1.4 seems to overexpose compared to my 24-70/2.8, probably by around half a stop (or maybe even more). Is this sort of thing normal?

  2. #2
    PhotoJim's Avatar
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    To some degree, yes. The more elements are in a lens, the less light will be passed. Cinematographers use T-stops (which consider lens transmission, not just the focal length-aperture ratio) to ensure that they use the right aperture.

    Also, at wide apertures some lenses will be more prone to light falloff, which can darken the corners.
    Jim MacKenzie - Regina, Saskatchewan, Canada

    A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.

    Favourite film: do I need to pick only one?

  3. #3

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    to some degree yes. Up to half a stop, I have seen. More than that then one of both of the lens aperture setting is considered out of whack.

  4. #4

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    The more I use the Soft Focus lenses such as Verito's, the more I think I am seeing a stop or more of exposure in 8X10, compared to say a Commercial Ektar
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

    Regards
    Bill

  5. #5
    wiltw's Avatar
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    The indicated aperture is just that... 'indicated' and not always 'actual'. Very common in lens tests from Modern Photo and Pop Photo in past decades to see deviation from the advertised f/stop!

    And even if the lens has a true aperture matching the rated speed, there is also the transmission differences that might be caused by multiple optical groups and loss of transmission efficiency in the air-to-glass interface.

  6. #6
    benjiboy's Avatar
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    Yes, particularly if they have between the lens leaf shutters, It's a case of getting to know your own equipment .
    Ben



 

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