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Author Topic: How to get a sharp image front to back?  (Read 4226 times)
BartvanderWolf
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« Reply #20 on: September 02, 2012, 05:52:05 AM »
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Good suggestion from Slobodan, but you need to choose the circle of confusion according to your viewing distance and print size. The 0.03 mm is an old standard based on smallish print viewed at 25 cm. A large print viewed at short distance will be most demanding.

Hi,

I agree with Erik, the COC diameter used in that web tool is much (approx. 3x) too large for critical work where larger output may be required. Personally I prefer a tool like VWDOF (a Windows only application), which allows to set one's own COC criterion, and output a number of different scenarios. It also allows simple text output which is easy to use in a spreadsheet or on a smartphone. That's what these DOF tools are most useful for, scenario testing before being confronted with a siuation in the field.

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Diffraction can be compensated with proper sharpening, at least to some extent.

That's correct, but how well that works also depends on microdetail contrast (and thus subject matter). It also helps to shoot at low ISO settings to reduce the noise, which will interfere with restoration sharpening. Low contrast detail will already get lost at apertures like f/5.6 - f/7.1 (for sensors with a 4.88 - 6.4 micron sensel pitch), and all microdetail (even high contrast) will be lost at f/22 on most sensors. And when I say lost, I mean without any possibility for recovery, lost. Depending on the lens quality and sensor, f/16 or f/18 are at the limit of being able to resolve fine branches against a bright sky, but lower contrast detail on the ground (soil/sand/twigs, grasses, leaf detail) will be compromised.

So the recommendation is to use an aperture as wide as possible, and as narrow as needed. As for what is needed, there is also a possibility to use focus stacking which requires multiple exposures at different focus distances, and not too much motion (branches swaying in the wind may cause 'ghosting' problems).

Cheers,
Bart
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BartvanderWolf
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« Reply #21 on: September 02, 2012, 06:11:58 AM »
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The three methods above produced a similar result - everything is in focus except that it's not razor sharp, but reasonably sharp - this is before applying any sharpening but I think Lightroom applied a 'default' sharpening value of "25" which is applied to all the images including sample (1) above.

So my conclusion is that my way of focusing works for me, however maybe my lens sucks? Maybe it's a bad copy because it has fallen on to the concrete once.

How sharp is "razor sharp" for an image produced by 1ds3 or nikon d3x / d800e etc? Hard to compare different photos / scenes / lighting situation unfortunately. Is it the case that the only way to find out is to get a rental and try and shoot the same stuff with different cameras / lenses?

For those who don't shy away from doing some fundamental work, it is possible to find the optimal Capture sharpening settings for any lens/aperture/sensor combination. The best results can be had with a proper Radius setting to start with, then the Detail slider setting (try 50 or more if diffraction plays a larger role), and finally the Amount, to push things as far as the quality allows. Masking will reduce the effects of noise in smooth (e.g. sky) regions. Noise reduction also plays an integral part in the sharpening effort.

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And here's the dirty question: will MFDB + technical camera (with tilt) totally solve the 'sharpness' issue?

Yes, tilt will solve some of the issues, but not all scenes can be shot equally well. There are still DOF limitations but they become more vertically oriented than depth/distance oriented. See the article from Anders Torger for some more info on Tilt related issues in landscape photography.

Cheers,
Bart
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shaunw
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« Reply #22 on: September 02, 2012, 06:26:25 AM »
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Essentially your technical issues are easy to solve...hyperfocal distance focusing will get you acceptably sharp throughout the image and do a net search for your lens sweet spot (very basically, f8 and stay away from extremes of focal length is generally accepted as sweetest. ive rarely found a need to stray beyond f16 for landscape scenes.

Back to the image....like that, cracking colours and sky....defo worth a trip back there armed with all the tips posted here. If you find yourself not in possession HFD charts/apps etc try focus a third of the way into the frame and review the image at x10, adjust as needed.


Shaun
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Canon 5D mk II Sigma 10-20, Canon 17-40mm L, Canon 24-105mm L, Canon 70-200 L, Lee Filters, Manfrotto geared head/tripod.

''Twelve significant photographs in any one year is a good crop''. Ansel Adams
http://www.shaunwalbyphotography.com
Jim2
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« Reply #23 on: September 02, 2012, 06:37:43 AM »
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I applied "Lens Correction" on Lightroom which seems to remove most of the reddish CA. The green spots I suspect are actually the real thing captured. It's just the beginning of spring so most of the grass is brown but some have grown green leaves in parts - not sure.

I've also played a bit more with Sharpening and setting "Detail" to 50+ and increased radius a bit, and readjusting sharpening level as much as possible but without causing a defining line between contrasting objects. I've also readjusted the Noise Reduction + increased color noise reduction too which resulted in removal of a lot of reddish blotches in the trees in the foreground.

Result of 100% crop attached, before and after.

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Jim2
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« Reply #24 on: September 02, 2012, 06:39:43 AM »
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I just noticed the red dot in the picture - this is a result of the cmos sensor exposing for too long? Clone tool will fix it!
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Jim2
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« Reply #25 on: September 02, 2012, 06:50:02 AM »
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Back to the image....like that, cracking colours and sky....defo worth a trip back there armed with all the tips posted here.
Shaun
That was a once in a lifetime sky (aren't they all? Smiley) - I went back there today - clouds were too low didn't even see any sun light. All dark grey.

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shaunw
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« Reply #26 on: September 02, 2012, 07:22:45 AM »
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That's a shame Jim...it's not just me that happens to then....lol. I think there is a lot to be said for having a well established familiar technique when it comes to landscapes...I just spent a week in the mountains my techniques, which I considered second nature needed some concentration after a fitful cold night in a bivybag and shooting at dawn. Find a setup frame expose and shot routine that works for you and work it until you can do it half asleep....as you often will be lol. I look forward to seeing more of your work.

Shaun
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Canon 5D mk II Sigma 10-20, Canon 17-40mm L, Canon 24-105mm L, Canon 70-200 L, Lee Filters, Manfrotto geared head/tripod.

''Twelve significant photographs in any one year is a good crop''. Ansel Adams
http://www.shaunwalbyphotography.com
degrub
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« Reply #27 on: September 02, 2012, 08:03:52 AM »
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since you mentioned the lens has been dropped - Roger Cicala at Lensrental.com has a couple interesting articles.
http://www.lensrentals.com/blog/2012/08/a-tilted-element-demonstration

http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover

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