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derekt

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  • Posted on: Canon TS-E 50mm f/2.8L Macro Review

    Under 'obvious applications' the major one missing is commercial product photography - websites, catalogues etc. This would be an ideal lens
    • 15 Nov 2017 11:39AM
  • Posted on: I'm Back Digital Back Kickstarter

    Samellos' reasoning in his post is illogical - it doesn't stand up. It'd be good to see the rear of one of these adaptations to see where this digiback sits/projects, i.e. can you still get your eye to the viewfinder without breaking your nose?
    • 18 Oct 2017 1:37PM
  • Posted on: Irix 15mm f/2.4 Review

    Depth of field is determined by 2 factors: aperture and magnification. i.e. not angle of view or focal length. Same view of caravan above (same size in frame) taken by a 15mm and 50mm will have same DOF. Cutoff to out of focus will be more dramatic with longer lenses, but DOF is about what is in focus not what is out of focus. The effect of the wide angle to give apparent DOF is only due to lower magnification, if you moved in closer it would disappear thus proving it's not a 'feature' of the lens.
    • 26 Oct 2016 12:42PM
  • Posted on: Canon EOS 100D DSLR Review

    I agree with the observation about lens size. What's missing are more small lenses to go with it. The 40mm pancake is a great option for a short tele and the combined size and weight would make this a pocketable combo. But who wants just one tele lens or bigger primes and zooms? The best idea would be to convert the 22mm pancake (from the M series) to use on this body, producing a semi-wide walkaround lens that would be a winning combination for me and, I suspect, many others ...despite it being too small for my hands
    • 5 Jun 2013 10:54AM
  • Posted on: Pentax 645D V Canon EOS 1Ds Mark III Comparison

    Neither Gary's nor Vic Barnes' comments on DOF are entirely correct. DOF is determined by aperture and magnification ONLY. The lens used is irrelevant. Somebody wrote that wide angle lenses have more dof in an amateur article way back when, so all journos have been quoting it ever since.

    Bigger format = greater magnification thus less DOF. Macro shots = greater magnification thus... etc etc ... you get the picture. Try using 10x8 film to see DOF of a few millimetres on head & shoulders portraits - doesn't matter what distance or lens, if it's head & shoulders, you get the same DOF (but not the same perspective, as Vic pointed out).

    Vic is correct that if you fill a frame with an object it will have same DOF (at same aperture). If you put a wide angle on and walk closer to fill frame in same way. Just zooming out or fitting a wide angle will have more DOF but it isn't the same shot, so the 2 aren't comparable. Likewise if you take in the same (wider) view by moving back with the tele lens fitted, that would have more DOF too (the same amount) - it's not the lens.

    As per which camera/format/price combination? If you have the dosh and muscles and time, get the pentax (or a Phase One) otherwise a 5D mkII!
    • 25 Feb 2011 4:22PM

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