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Iris and diffraction

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Carlo Ferraro
Iris and diffraction
on Sep 7, 2010 at 7:38:12 pm

The lens closes up to f11, what would be the best aperture to avoid iris diffraction on bright sunny illumination?


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john lenihan
Re: Iris and diffraction
on Sep 16, 2010 at 11:41:45 am

Carlos,

I have not done any conclusive tests, but I have observed that if the light is brighter than about a 5.6, the camera will say something like ND1 or ND2 to suggest using the neutral density filter to avoid the aberation. I think that is the camera manufacturer giving a hint.

I usually stay no smaller than an f8 unless I am looking for a specific look. Since you have two ND filters and can set the shutter speed high, that is not a problem.

John Lenihan


LeniCam Video Productions
http://www.lenicam.com

John Lenihan

LeniCam Video Productions
http://www.lenicam.com


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Carlo Ferraro
Re: Iris and diffraction
on Sep 16, 2010 at 5:23:48 pm

I'read a technical review wher the author states that the optimun apreture was 4.4. I made som trials stating at f11 and endid up at 4.4. I blew up the image up to 8x and found that really resolution is lost over 5.6, being mor noticeable at f11, together with contrats lost. I have been working so far at f5.6 and the image looks great all the time, wheter with sun or on open shade.
Another problem is shutter, I've not been able to do a decent slomo to 50 or 30% with any shutter speed from 50 to 200. Using the device on the camera to record at 215fps is a piece of crap, at 3 secs the image is only worth if you use it at 1/4 of the screen size.


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john lenihan
Re: Iris and diffraction
on Sep 16, 2010 at 6:04:40 pm

Thanks Carlos,

Would you like to upload the results of your tests?

Regarding Slo Mo, I didn't know that the NXCAM even had that feature.

John Lenihan

John Lenihan

LeniCam Video Productions
http://www.lenicam.com


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Carlo Ferraro
Re: Iris and diffraction
on Sep 16, 2010 at 6:19:49 pm

I simply blew up consecutive frames on Final Cut at different apertures and went from frame to frame continuously to see the difference on a led display.Nothing Pro, just visual experience and 40 years of doing photography, the eye is the ultimate judge. Try the slomo....


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