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smaller baffle plates?

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  • #16
    Re: smaller baffle plates?

    Originally posted by mike_j View Post
    I'm no optics expert but I should think that a rough edge to the aperture of the baffle might cause small scale distortion/diffusion which would degrade the image slightly. I haven't tried making a baffle yet so this is only conjecture.

    I think I will laser cut some 'perfect' 17mm dia holes in some thin acrylic and run some comparisons. Blacked shim steel would be better but I can't get that laser cut (at least not free).
    True - more a proof of principle rather than a finished article - definitely better even with my half-arsed job! The hole diameter is about 18mm - so beyond area where it might interfere, but it should still cut down reflections. Given the CCD is shiny (more so than film), it will be impossible to completely cut down all returned light. It is interesting that lens sold by, say, Nikon and Canon for APS-C/DX and full-frame should also benefit from the baffle on the smaller sensor - as should four-thirds Sigma DG (i.e. derived from full-frame) unlike the DC lenses.

    Andy
    Olympus E-M1 ZD 7-14 f4, 300 f2.8, PL 25 f1.4D
    mZuiko 12-40 f2.8 Pro, 60 f2.8, 40-150 f2.8 Pro
    EC-14, EC-20, HLD-7
    Metz 58 AF-1&2 , Manfrotto 441, Gimbal Head, Velbon Neopod 74


    Gallery: http://picasaweb.google.co.uk/elliott.aje.andy

    Website: 361photography.com 361wild.com

    "Oly_OM" @ e_group

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    • #17
      Re: smaller baffle plates?

      I just read this thread with great interest. I was just about to make a baffle for my Minolta-4/3s adapter. I wanted to double check what the diameter of the center hole should be. I read both 17mm, and 18mm in this thread. I grabbed a 14-54mm lens, and the rear element measures 18mm from edges of the glass.

      I then started wondering if all the ZD lenses have the same size baffles and rear elements. They do not. The faster the lens, the larger the rear element, and also the baffle. The 35-100mm baffle has a giant opening in the baffle compared to the slower lenses. See attached pic.

      So now I'm wondering if an 18mm hole in my homemade baffle is not a good idea. Since the 35-100mm is f2, a legacy lens like a 50mm f1.2 or f1.4 seems like it should have AT LEAST the same size hole in the baffle as the 35-100mm lens.

      What do you guys think?

      Marc
      Attached Files

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      • #18
        Re: smaller baffle plates?

        I'm going to have to give this a try with the OM 20mm.

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        • #19
          Re: smaller baffle plates?

          I measured the rear of the 11-22mm and came to 27mm, so the should be some play.
          On the other hand the Olympus Digital lenses have a better control of how the light strikes the sensor: straight on instead of under an angle.
          I just have my old 1.8/50mm left.....

          But with some black cardboard you can draw a number of circles on it and start with the smallest one and use the hole that gives you not dark corners.
          That should be the propper baffle, purely theoreticly ofcourse.

          Time to experiment !

          Peter

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