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Thread: 100 mm lens shot

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    Default 100 mm lens shot

    Hello All,

    I wanted to know, and I am not a scientist so go easy on the answers, when I shoot (example: a face and shoulders) with a lens of 100m, and do it again with a different lens set to 100mm, and a third , why there are subtle differences in the renditions.

    I have a 100-300, and a 70-200, and a 28-135, they really are not alike. The nose is different in each for example.

    I can do the same thing at 50mm using a 50mm lens, and the 28-135 at 50 mm.

    Any theories or factoids?

    Thanks,
    Ujay.

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    Default Re: 100 mm lens shot

    Hi Ujay, welcome to the forum!

    There are a couple of things that I can think of that might influence the rendering of the same subject differently by different lenses.

    Most zoom lenses, in particular those with internal focusing, are actually focused closer by a shortening oft the focal length. It means that 100 mm on the zoom scale is less than 100 mm in reality and hence the image will be rendered at a smaller scale compared to a real 100 mm lens.

    Different lenses may not allow the same maximum aperture (minimum f/#) which, in turn, influences the depth of field (DOF) and hence also the rendering of the subject. If the focal length is the same, this effect is only noticeable when shooting at the largest apertures when DOF is limited.

    Another effect may be that the rendering of the out-of-focus parts of the image (so called 'bokeh') is different for each lens. for a portrait situation, one would again need to shoot at the largest apertures in order to see any distinct effect on for example the rendering of the nose. When stopped down, the DOF will be large and only the background will be affected by different bokeh.

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    Default Re: 100 mm lens shot

    All of what Jens says is correct but there's also something else you may not have thought of. It's not always the lens that makes the difference but the metering. If you're spot metering especially, but not only and on one shot you have the metering spot on something light in color, as in a highlighted part of the face, the overall image will be a little darker. If the next shot you happen to move your lens over just enough to get the metering spot on somethig darker, as in a shadowed area on the cheek, the overall image will be a little lighter. It's basic but when I was new to photography it took me a while to figure even that out.
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    Default Re: 100 mm lens shot

    One other thing is, the 100mm mark is at a different part of the zoom range in all three lenses, so the perceived look will be different because of the differences in lens elements shape, mountings etc,
    like the diff between a 10mm fish eye and a 10mm regular WA, just not that exaggerated
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