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IQ3-100 with C1 10 Diffraction "correction".

Bill Caulfeild-Browne

Well-known member
One of the latest features of C1 is Diffraction Correction in the Lens tab. Today I set out to see how effective this is. All shots were taken with a sturdy Gitzo, Cube, Electronic Shutter and Vibration Delay, focussed with Live View and triggered with Capture Pilot. The lens is the BR SK 150 f3.5 as it goes down to f32. All shots with C10 defaults only.

The first shot is at f5.6 where there should be no diffraction. (F8 and F11 were virtually indistinguishable from F5.6 so I have not posted them.) The second is F16 with Diffraction Correction, then F22 and F32 likewise with the correction..

Looking at JPGs, even at 100%, really doesn't show the differences. But at 100% in C10 on my screen I can see clear improvements, particularly in the texture of the label. The F16 shot looks almost as good as the F5.6 and much better than before the correction was applied. F22 is also improved but is clearly not as good as F5.6. The F32 shot is, well, really crappy before correction and not a lot better with it.

My conclusion from my monitor is that the DC is very well worthwhile at F16 and certainly a help at F22. F32 is improved but nowhere as good as the F5.6 shot.

F5.6


F16


F22


F32


PS - not sure why the blue cast appears on the F5.6 shot, upper right side! May have been a result of changing lighting.
 

bab

Active member
Bill
This lens focuses down to 5.5ft not sure at what distance you shot the images of the label.
I put this into the Pro-Optumum CSP calculator and I (maybe I don't know how) cant seem to get a blur diameter reading at 5.5' except upwards toward 200. If I use a focus distance of 80' I can bring the blur diameter down to a respective reading. What I saying limited on my understanding of you tests Im not sure that lens depending on the (distance you selected) running the image thru C1 show you any diffraction correction?

Barry
 

Bill Caulfeild-Browne

Well-known member
I shot the images at about 9 feet. I'll post some "before and after" correction images tomorrow - they may be more informative than contrasting them with an F5.6 image.
 

Bill Caulfeild-Browne

Well-known member
Here's a different way of seeing the correction. SK 120 BR at f22, no output sharpening. First is uncorrected, second is with Diffraction Correction applied. All other settings C1 defaults.




 

Wayne Fox

Workshop Member
Bill
This lens focuses down to 5.5ft not sure at what distance you shot the images of the label.
I put this into the Pro-Optumum CSP calculator and I (maybe I don't know how) cant seem to get a blur diameter reading at 5.5' except upwards toward 200. If I use a focus distance of 80' I can bring the blur diameter down to a respective reading. What I saying limited on my understanding of you tests Im not sure that lens depending on the (distance you selected) running the image thru C1 show you any diffraction correction?

Barry
I'm not sure I understand what you are saying. seems like diffraction is based on the size of the aperture and the percentage of light getting "bent" by passing near the blades, which of course dramatically changes as the aperture gets smaller. I'm not seeing how this would be affected substantially by where the lens is actually focused.
 

4*Paul

Member
Prompted by Bill’s post, I decided to try out the C1 10 “diffraction correction” with Rod 40mm & SK 60mm lenses on an Alpa STC and an SK 120mm macro on an XF – all with the IQ3 100.
Focus distances varied from approx ∞ down to <0.5m/20 inches (XF) and found that f16 corrected appears to be remarkably similar to f8 uncorrected, on all lenses, ISOs and distances used.
Not a controlled test but I was surprised and impressed by how well the correction tool worked - and at just how much extra DOF (with 100MP levels of sharpness) you get at f16!
I haven't gone that far down the aperture scale for over 30 years so will be looking for a bottle of Combe aux Jacques to celebrate.
Cheers Bill.

Paul.
 

4*Paul

Member
Now try f22, Paul! It's pretty usable IMHO.
Bill, I did shoot a few frames at f22 as well but, although the correction tool made a definite improvement, I felt that they were still a bit soft when viewed at 100%.
That’s only in comparison with the very high standards of the IQ3 100 and, I suspect that they would still make very acceptable prints.
So just need to get out there now and make use of the new-found DOF.
Paul.
 

Bill Caulfeild-Browne

Well-known member
Yes, I agree a truly sharp F22 would be magic - but it is usable in a pinch. (Stacking and Helicon Focus would be a better solution if the subject permits....)
 

TimoK

Active member
Do anybody know what is the technique behind this "diffraction correction"? I'll bet convolution sharpening with smart settings for current aperture.
I don't have C1, so I ask if you can adjust amount of correction, or is it only depending in F value in EXIF data?
Can you manually set aperture value (different to real F-number in shot) ? If so , What are the results if you apply e.g. F32 or F45 correction to F22 shot?
 

Wayne Fox

Workshop Member
Do anybody know what is the technique behind this "diffraction correction"? I'll bet convolution sharpening with smart settings for current aperture.
I don't have C1, so I ask if you can adjust amount of correction, or is it only depending in F value in EXIF data?
Can you manually set aperture value (different to real F-number in shot) ? If so , What are the results if you apply e.g. F32 or F45 correction to F22 shot?
It's based on deconvolution, but I can't see anyway to manually set an aperture value. You can set the lens, and of course it knows the back that was used. So any aperture value used is based on EXIF. The webinar specially states the aperture value is used in the formula so I'm not sure what they are doing if you are using a tech lens.

I've tried it on a few images with very little difference, but most of my images are shot at f/8. I need to find some where I closed down to 16 or 22 and see what I get.
 

etrump

Well-known member
The f/22 correction even looks promising IMO. A little post could make it close enough to the corrected f/16 that you would never notice in a print.

In the old days of anti-aliasing filters I had a simple overlay correction that used emboss to offset the alias blur. Would be interesting to try that on the f/22 and see how close I could get the wider apertures.

Very interesting Bill and the discussion is valuable.

Ed
 

John Black

Active member
It's based on deconvolution, but I can't see anyway to manually set an aperture value. You can set the lens, and of course it knows the back that was used. So any aperture value used is based on EXIF. The webinar specially states the aperture value is used in the formula so I'm not sure what they are doing if you are using a tech lens.

I've tried it on a few images with very little difference, but most of my images are shot at f/8. I need to find some where I closed down to 16 or 22 and see what I get.
Wayne, I don't know if this app is compatible with Phase One raws - https://exifeditorapp.com. I use it to backfill missing data on my Leica DNGs, including aperture values, lens names, etc. I've not played much with deconvolution, but it needs the distance too, right?
 

EsbenHR

Member
It's based on deconvolution, but I can't see anyway to manually set an aperture value. You can set the lens, and of course it knows the back that was used. So any aperture value used is based on EXIF. The webinar specially states the aperture value is used in the formula so I'm not sure what they are doing if you are using a tech lens.
You can set (or overrride) the aperture in the movement tab of the lens tool. The reason it is there is because of, well, technical cameras.

You can play with it, but don't expect good results if you lie to your software. It is a nice piece of software, why would you lie to it :)
 

Bill Caulfeild-Browne

Well-known member
:OT:


I've had it and liked it! Curious to hear what you think. And reasonably priced too!

Dave
Opened it tonight. None left in the bottle.....which probably answers your curiosity! Joking aside, quite light and nicely rounded - a very nice casual drinking wine.

Cheers!
Bill
 
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