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GH2 - Difraction test for the M.ZD 45mm F/1.8 - 100% Crops.
  • When comparing neighboring apertures the effect it's not very apparent but usually comparing crops 2/3EV apart you will see a difference. Having said that, I can say I'm pretty confortable up to f/11-13 even though if you compare to f/9 you can spot a marginal difference. These are 100% crops. Had to shoot these at ISO640 because that was the needed amplification for F22@2fps. Shot on tripod with constant lighting. At very wide apertures (F/5.6 and faster) there is flickering from the lighting but it doesn't make a difference for this purpose.

    BTW I also tested with a chart on the center and another on the corner but the diffraction settles in equally as expected, so I'm publishing this test where I zoomed in on the chart and it's easier to see the differences.

    A zip file with all images is also here:

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  • 9 Replies sorted by
  • @Vitaliy_Kiselev : I wondered whether I should post that in the Lenses Section, but then I though "Diffraction is a sensor characteristic" so it will be similar for all lenses that out-resolve the sensor (and at video resolutions mostly all will) so I posted here in the Camera Section.

  • @duartix Great to see the tests. :)

    Though diffraction affects all lenses, the aperture where you start to lose resolution varies from lens to lens.

  • This test is extremely useful for astrophotography which I am heavily invested(literally) right now. Most scopes are F10 out of the box. Any barlows at all will push it out to F20 and beyond.

    I bought an 8" 800mm F4.0 scope so I can use a 3x barlow without much issue. I have a 2x, 3x, and 5x on the way. I can also use the 2.6x and 3.9x ETC features to get around the diffraction issue at extreme amplification.

    I laugh when everyone asks why there isn't a 800mm F4.0 lens for m4/3s. Attached is a picture of a reasonably priced 800mm F4.0 lens. Trust me this will not fit in your pocket.

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  • @mpgxsvcd : Is it stabilised? How much was "heavily invested"? And I don't mean pounds... oh wait, perhaps I do, where in the planet are you?

  • A 600mm f/4.0 Canon L series costs over $10,000 U.S. - tack on another $500 or so for 2x extender. Not sure how the telescopes compare but that`s the most expensive I used for astrophotography so far and with the case it was ca. 30 lbs to carry around.

  • I live in North Carolina in the US. The 8" Astro tech weighs about 20 pounds. The scope itself was only $499 and it is just about perfect for most deep space objects. The real cost is a decent Goto German equatorial mount and all of the accessories that go with it. I have about $2000 invested into those.

    The scope wouldn't be very useful for day time application. It is very useful for AP though.

    I am working on a video tutorial on how to do Astro Photography from a heavily light polluted back yard on a budget. We finally have clear skies tonight so most of the footage will come from tonight's session.

  • LOL I have exactly the same set-up 8" F5 reflector - sadly bang in the middle of London - got some nice shots of Jupiter and moons though the other day

  • @soundgh2

    I find that the 2 minute 8 second exposure limit of the GH2 means focal ratio is everything. That is why I went with the F4.0 scope instead of an F5.0 or greater. The 800mm focal length is nice as well. It allows me to frame the full moon in 16:9 perfectly and Orion's Nebula just fills the frame.