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Author Topic: Is the problem of diffraction over-rated?  (Read 17132 times)
Jack Hogan
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« Reply #60 on: March 25, 2013, 08:22:03 AM »
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One of my favorite images is this one, which is worth a look whenever one is getting too obsessive about detail. It predates DSLR's, I believe.

Hi Ted,

Yes, quite interesting.  And eye-opening.
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Jack Hogan
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« Reply #61 on: March 25, 2013, 08:36:13 AM »
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The important notion is that InFocus combines 2 operations, first a generic (or deblur) deconvolution, and second an optional sharpening operation. One should probably not try and solve the entire blur issue with only a single deconvolution (because you have no influence on the 'strength' of the effect), they are supposed to work in tandem (although I'd rather prefer more control over the deconvolution process). The optimal deconvolution radius setting seems to correspond reasonably well with the Sigma radius that my tools determines, maybe dialing in a tad smaller radius can help avoid the generation of excessive artifacts. It is not obvious which deconvolution method (generic/deblur) would be best. Deblur seems a bit more aggressive, it seems to be more than just a different PSF shape. Many unsatisfied reactions are caused by using too large a deconvolution radius. Assuming the two operations are executed in sequence, the sharpening radius to use should then be smaller than the deconvolution radius, unless one tries to achieve creative sharpening.

Hi Bart,

Thanks, interesting that.

I generally try 'Estimate' with a 2 radius, 0.3 softness and 0.2 artifact suppression first.  It typically works pretty well on my landscapes, but if I think it is being too aggressive I will switch to Generic and play with the radius, leaving artifact suppression at 0.2.  Radius usually ends up between 0.9 and 1.3.  I virtually never use the built-in optional 'classic' sharpener, preferring to do that elsewhere.   Maybe I should give it a second chance.  Does it work as well/better than what you can typically achieve later in the workflow?

I think I like InFocus a little better than the FM trial I've been playing with.
« Last Edit: March 25, 2013, 08:40:18 AM by Jack Hogan » Logged
BartvanderWolf
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« Reply #62 on: March 25, 2013, 09:17:45 AM »
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I generally try 'Estimate' with a 2 radius, 0.3 softness and 0.2 artifact suppression first.  It typically works pretty well on my landscapes, but if I think it is being too aggressive I will switch to Generic and play with the radius, leaving artifact suppression at 0.2.  Radius usually ends up between 0.9 and 1.3.

Hi Jack,

Yes, 'Estimate' sometimes works fine, sometimes not. It depends on the subject and the location of the focus plane. It's too bad one cannot import a custom made PSF kernel. Maybe something for the long overdue updated version.

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I virtually never use the built-in optional 'classic' sharpener, preferring to do that elsewhere.   Maybe I should give it a second chance.  Does it work as well/better than what you can typically achieve later in the workflow?

No, not necessarily. It's just that one shouldn't try to do everything with only a single deconvolution pass. For very good control over subsequent 'Creative sharpening', their 'Topaz Labs Detail' plugin is very useful. It's like adding Clarity on steroids, to be used with restraint but very powerful.

Cheers,
Bart
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Jack Hogan
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« Reply #63 on: March 25, 2013, 09:28:34 AM »
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For critical work, I suggest that an aperture of 5.6 is likely optimal with the D800e. What do you think?

Hi Bill,

I was thinking about your comment above.  I hope I am not saying something too obvious but total system sharpness is fully dependent on the contributions of individual system components.  In other words total system MTF is the product of individual component MTFs (or the convolution of individual PSFs).  The way you maximize system MTF is by maximizing each component MTF - independently of the others.

All this to say that the best aperture with a given lens to maximize MTF is that best aperture period, independently of whether you are shooting with a D800e or a D40.  The difference is imo that with a 'e' you will notice much sooner when you are not in the sweet spot.

Cheers,
Jack
« Last Edit: March 25, 2013, 09:36:44 AM by Jack Hogan » Logged
Jack Hogan
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« Reply #64 on: March 25, 2013, 09:34:55 AM »
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No, not necessarily. It's just that one shouldn't try to do everything with only a single deconvolution pass. For very good control over subsequent 'Creative sharpening', their 'Topaz Labs Detail' plugin is very useful. It's like adding Clarity on steroids, to be used with restraint but very powerful.

Agreed, Bart.  Detail reminds me of my first motorcycle, a Suzuki GS650: way too powerful for my own good.  I stopped using it shortly after purchase as well, as a result of a couple of near fatal crash-and-burns.  Great fun though  Smiley
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