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Author Topic: Diffraction confusion.  (Read 5747 times)
Petrus
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« Reply #20 on: February 07, 2013, 11:39:28 PM »
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The first time I noticed diffraction in real life was when doing some macro photography, where stopping down is necessary for DOF. Lo and behold, pictures actually started getting softer after f:11 (shooting with 16 MPix FF body) and f:22 was already quite bad and f:32 even more so. These were not for exhibition prints and for a half page reproduction even f:22 was usable, but the effect of diffraction was crystal clear.
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ErikKaffehr
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« Reply #21 on: February 08, 2013, 12:31:18 AM »
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Hi,

This is a good example of loss of image detail:



The line pattern is not visible on the f/16 image on the left but clearly resolved in the f/5.6 image. Both images deconvolution sharpened in LR.

Full article: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/68-effects-of-diffraction

Best regards
Erik




The first time I noticed diffraction in real life was when doing some macro photography, where stopping down is necessary for DOF. Lo and behold, pictures actually started getting softer after f:11 (shooting with 16 MPix FF body) and f:22 was already quite bad and f:32 even more so. These were not for exhibition prints and for a half page reproduction even f:22 was usable, but the effect of diffraction was crystal clear.
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BartvanderWolf
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« Reply #22 on: February 08, 2013, 05:59:43 AM »
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In a real world, ignore the theory. Use the diaphragm stop that will give you the depth of field that you require, and that's all you need worry about.

Hi Rob,

The problem with such broad sweeping statements is, that they are worthless advice in specific circumstances that many professionals and amateurs alike encounter on a daily basis. Granted, some of those are not producing 'artistic images' where blur and lack of resolution can be coined to be a feature rather than a flaw.

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Folks have to realise that they are dealing with a photograph and not a laboratory test. Unless they actually do see their photography as a sequence of laboratory tests, in which case, good luck to them, and have fun.

That is also not helpful for those who want to make a more deliberate choice of their camera settings, understanding (all) the trade-offs involved. Mastering one's tools is also part of becoming a better photographer, and it's more fun than being mastered by one's tools. Do you shoot with your camera in Program mode, or do you deliberately choose a shutter speed or aperture priority for a given situation?

There apparently is still a lot of confusion about diffraction, which BTW is the topic of this thread, so if a few laboratory tests can help to improve one's understanding, I don't see the downside of that ...

Cheers,
Bart
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hjulenissen
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« Reply #23 on: February 08, 2013, 07:19:36 AM »
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Now that we have exposure bracketing (with in-camera hdr synthesis), flash bracketing, WB bracketing and what not, when are we going to have ergonomic focus bracketing?

"I want reasonable sharpness from 2m to 6.2m. I define sharp to mean a PSF not exceeding effective 3 pixels. Use the focus motor to take however many images needed, and let me know when you are done".

Or:
"I am touching the areas on my liveview touchscreen that matters to me (in terms of sharpness) in this image. Now make me an image that is sharp in those spots".

Some people would object to such automation, claiming that it is not "real" photography, and "where is the art in it when the camera does it all for you". Hopefully, Samsung does not listen to those, and choose to make cameras that help people make better images instead.

-h
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Slobodan Blagojevic
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« Reply #24 on: February 08, 2013, 09:40:57 AM »
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Wasn't Contax N (or whatever the designation was) providing focus brackating already years ago? Also, some Canon models used to have a mode where you select two focusing points and the camera calculates both the needed f/stop and sets the necessary distance to keep both sharp.
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Slobodan

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