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cbeasley

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About cbeasley

  • Rank
    Sea Wasp

Additional Info

  • Show Country Flag:
    United States
  • Camera Model & Brand
    Olympus OM-D E-M5 mk ii
  • Camera Housing
    Olympus PT EP 13
  • Strobe/Lighting Model & Brand
    2X Inon D2000
  1. This is a very useful experiment. Thanks! I did something similar and my results agree with yours. However, I think the way you state the magnification is a little unusual. To my mind, magnification is the ratio of the sensor size divided by the actual, real world size of the image. So, when you show you get about 18mm at the closest focus range for the 60mm lens, the magnification is 17.3/18 = .96x. Olympus quotes this lens as a 1:1 macro lens, so a 1X magnification, so this is very close and reasonable for a field test. I measured about 13mm (horizontal) with my E-M5 mkii, underwater with the Oly 60mm lens and INON 165mm diopter (said to be +6). This yields 17.3/13 = 1.33X. Again, thanks for all the tests, but I think your magnifications are different from what one would normally use. After all, the only thing that matters is that you will be recording the image on the m4/3 sensor, not a 35mm sensor. I should mention that the crop factor is a factor of about 2, so what is true is that one would need a 2X60mm 120mm lens on a 35mm camera to achieve the same magnification. Another question I have been researching is what magnification loss occurs if one uses a dome port with the 60mm lens. I wonder because I find my Zen port VERY difficult to change. Even after lubricating with siliconne, I still need a strap wrench and a lot of effort to get it on and off. Anyway, according to my tests, if you use the Oly 60mm macro behind the Zen 4" dome, max image size is about 22mm. So in this case, you get 17/22 = .77X. This is a 25% reduction in magnification, which might be acceptable in some situations. Perhaps there is image distortion too, so if anyone can comment on that, please do. Also, any tips on how to make the Zen port easier to change? The flat port can be turned by hand!
  2. I'm a new member because I have kept running into this site when I do searches. I decided I'd like to join some discussions, hence I am joining now.
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