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Thread: Well said, Robert

  1. #1
    Member SpringfieldPhoto's Avatar
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    Oct 2016
    South Wales

    Default Well said, Robert

    I had to respond to Robert's excellent article, Outspoken EOS. I spend hours on this subject in my capacity as Training Officer for my camera club. Members are confused by this subject and Canon, along with other manufacturers and several magazines, perpetuate the myth that placing a lens on and APS-C camera, magically changes its properties.
    I recently showed some pictures that I had taken with a 50mm lens using an aperture between f2 and f2.8 on my 5D Mk IV and was asked how I managed to achieve the blurred backgrounds so well when they couldn't using a 35mm lens and similar apertures. This is a common problem and one that I have to deal with with each new inexperience member and more worryingly with many experienced members.
    The Myth appears to be heavily embedded. I recently set up a presentation using some pictures that I took specially for the job.
    I took pictures in my studio using my 5D Mk IV, a borrowed 7D Mk11 and my old Zenza Bronica SQAI with 100 ISO film. I used 50mm on the 5D and 50mm 'equivalent' lenses on the other two cameras. I carefully set things up to get the same field of view for each and used f2.8 on all the lenses. The resulting shots were quite convincing as you might expect.
    Anyway, thank you Robert for the article, I shall be making reference to it in future presentations to the Club.

    2 5D Mk IVs, EOS 3, Canon 20mm f2.8, Sigma 35mm f1.4 Art, Sigma 50mm f1.4 Art, Sigma 105mm f1.4 Art, Canon 85mm f1.4, Tamron 24-70 f2.8, Sigma 70-200 f2.8 and Sigma 150mm f2.8 macro.


  2. #2

    Default Re: Well said, Robert

    Robert is of course correct.
    At my local camera club, at least two pro photographers who visited have stated that the APS-C body gives more reach and lens "magnification" which shows how embedded these myths are.
    I used to have a little sympathy with the "more reach" idea (not the lens multiplication factor) when comparing APS-C sensors with FF with larger pixels. If the pixel size is smaller between two bodies, then that would, in principle, provide higher resolution. When the 5D had around 22 Mp at 6.25 microns and the 7D II 20 Mp at around 4.5 microns, there was some justification for 1.6x resolution (though the ratio is nearer 1.4x than 1.6x).
    With the 30 Mp 5D Mk IV even that, rather weak, argument has now disappeared.

    However, in accordance with other comments Robert has made in the past, I think there is still a little more to be said about field of view. This has come up before when comparing APS-C with FF. Although the DOF is always going to be controlled by the focal length of a lens, the aperture and distance in front of the lens to the subject, this last factor means that when using an APS-C body, an equivalent field of view to FF requires a lens 1.6x smaller FL when the subject is the same size in the viewfinder relative to the whole image. But the shorter FL lens will increase the DOF. So to create a similar field of view on an APS-C body to a FF means using a wider aperture. In some cases this might not be possible (e.g. if a portrait has been taken on FF using an 85 f/1.2 there is not a 50mm f/0.8 lens available).

    Can I raise a gripe of my own? That is the term "100% crop". I'd like to propose this is as meaningless as "1.6 crop", as to me, it implies "no cropping at all" i.e. 100%=full size. Of course in standard Photospeak it means cropping an image to the point where the displayed pixel resolution is the same as the image pixel resolution i.e. 1 image pixel= 1 display pixel. That may mean no change, or a big change, too, depending on the display resolution, so even this is open to different perceived resolution, which also depends on viewing distance, one's eyes resolution and so on.

    I'd prefer "50% crop" to mean, for a given image, it is half the original image size. In cases where the resolution is being compared, this might then be sized up to match the original to give a magnification, but that is a separate factor to the crop. "Enlarged crop" seems to me to be the term which accurately describes comparison shots.
    Don't suppose I'll get much support for this, but that seems more logical.
    Last edited by neonlamp; 04-04-2019 at 11:37.


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