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05-23-2022, 04:54 PM   #16
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You're really hurting yourself shooting at f22, Marinb!

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05-24-2022, 08:05 AM   #17
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I hardly if ever post, and I don't own a K1 and f22 would be the prime suspect... but I have had to callibrate the focus on my K7 and K3 MkII which were both pretty obviously bad and really annoying until adjusted and in both cases intially blamed on the lenses!
05-24-2022, 08:33 AM   #18
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Well if you listened to the pentax presentation you would know by now the old SMC coated lens are failing; In reguard to 1.4F to 2.8F would make no difference if your using 22F stop. Me I would take it outside on a cloudy day no sunlight and place your subject on the ground use a telephoto lens or even a mirror lens select the lens that suits the size image you want and try that. The reason it looks poor is too much light on one side then the same colour with the shadow on each grain creates an illusion of unsharpness hence getting rid of unnatural lightening then next possibly a f8 with a much faster shutter speed and and as low an iso that you can achieve k5 does 80 iso.with a zero to minus av setting. Also drop the light temperature so it's a brighter yellow (possibly and incandessant light) so the grain and shadows are more distinct you could even test a ringflash in flash mode there are alot of options to experiement with. Even placing it on a light box would create shadows from the grain if you didn't use a flash and all the shadows would be above the grain which would disguinguish each grain also. You can't just take a photo of that grain without being creative. Adjustable ND filters might also help.

Last edited by Kombivan; 05-24-2022 at 08:50 AM.
05-24-2022, 09:37 AM   #19
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Thoughts

On the other hand I admit I was trying to avoid some post production by using f 22. I understand it was a mistake because of the diffraction. I do use most of the techniques related above:

It is tempting. And gives inferior results. Been there. Done that.

1. the image above is focus stacked from 2 images - one focus on top, one focus on paper's surface.

Try focus stacking from 20 images. Youīll be surprised.

Generally speaking: The easiest way to get basically infinite resolution is to take a ton of detail pictures and stitch them together digitally.

2. I do use high pass to sharpen my images

Phew. It does not really sharpen. It enhances edges mostly. That would be the last step I think.
3. I am not using flat lighting. This light creates almost no shadow. I know the sidelight creates shadows and texture.
4. For some reasons, I thought pixel shift can not be used with flash, but flash is 100% my lighting source. I searched the manual - ... can not be used with X and B modes... Hm... I am always using M mode.
Frankly: Not much point in flash with macro for me. Not if it doesnīt move.

Other things to consider: Avoid vibration as good as possible. Stable tripod, stable table. Stable everything. Donīt even think about pushing the shutter release manually or trigger the shutter when the mirror is not switched up.
And donīt forget to switch off shake control. If you want to squeeze out the last bit of sharpness it wonīt help.
(Sorry if this is silly advice for beginners. Itīs just mistakes I made myself.)

05-24-2022, 10:11 AM   #20
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Go medium format digital. The right tool for the job.
05-24-2022, 10:32 AM   #21
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QuoteOriginally posted by grahamcoad Quote
Go medium format digital. The right tool for the job.
I'm not saying medium format - at least the right camera and especially the right lens - wouldn't work well (I'm sure it would), but I submit the OP can achieve what he wants with any format (m4/3, APS-C, "full frame" or medium format), a half decent macro lens stopped down to the optimum aperture (or close to that) and avoiding diffraction, and stacking of multiple shots taken at slightly different focus distances. I'm not against switching or adding formats to one's kit, but it's an awfully expensive move unless we've exhausted other options with existing gear...

Last edited by BigMackCam; 05-24-2022 at 11:35 AM.
05-24-2022, 10:59 AM   #22
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......

.....Nevermind. Previous comment was uploaded before I got mine posted

05-24-2022, 05:21 PM - 1 Like   #23
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QuoteOriginally posted by clackers Quote
You're really hurting yourself shooting at f22, Marinb!
Since the 100mm was used (I believe) the scores are even worse. at f/8 center 2092 vs f/22 1189.

unfortunately these are also tested at infinity and not close distance. My sigma 70mm macro at macro is incredible at f/8 but still great at f/16 where DOF means even more. with my 20 MP sensor by f/19 there is a significant drop but still pretty good but at f/22 it is terrible. keep in mind that at macro distance the effective aperture is much higher.
05-24-2022, 06:32 PM - 1 Like   #24
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Macro lenses are fairly simple optically, I strongly doubt that a decent macro lens from even the 70s is going to be significantly worse than a modern one. Pentax, Nikon, Yashica, Lester A Dine, etc are all respectable lenses.
05-24-2022, 08:24 PM   #25
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If you stop down past f/11 diffraction negatively affects things really fast.
05-24-2022, 09:47 PM   #26
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What I would be watching is how large you want to display the final product, how much you are cropping the image and base how much you stop down the lens when using first 2.

The more you crop the more diffraction you will see, the more larger you display the image the more diffraction you will see. If you are going to crop I would look at using a wider f stop, if you are using more of the image without cropping the more you can stop down the lens. For me if I am using most of the frame on a FF camera there is no problem stopping down to ƒ20 -ƒ32 for macro as long as you are using more of the frame.

If you are going to crop I would take into account how much you are looking to crop lets say you are only using a cropped 1.5 I would think about limiting it to ƒ15-21
05-24-2022, 10:03 PM   #27
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QuoteOriginally posted by Ian Stuart Forsyth Quote
For me if I am using most of the frame on a FF camera there is no problem stopping down to ƒ20 -ƒ32 for macro as long as you are using more of the frame.
But you notice a difference - during your post-processing at 1:1 reproduction - between the optimal aperture of, say, f/5.6 - 8 vs f/20 - 32, yes?

In the last few months I've been digitising 35mm and 120 film at home using a camera and copy stand - admittedly, with my APS-C K-5 and K-3 rather than a full-frame. To allow for film that wasn't completely flat, I initially used f/11 for greater depth-of-field - but opening the lens up to f/8 made a noticeable difference in critical sharpness when viewed at 1:1 reproduction on my laptop screen. Now, I can't really see that difference when the image is downsized to fit my display - but it's there nonetheless...
05-24-2022, 10:18 PM   #28
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QuoteOriginally posted by BigMackCam Quote
But you notice a difference - during your post-processing at 1:1 reproduction - between the optimal aperture of, say, f/5.6 - 8 vs f/20 - 32, yes?
Yes at 1:1 that's why its important to have a ball park as to how the image is going to be display.
Diffraction limit often promotes the wrong idea as to how much one should stop down a lens. take a FF 36mp camera shot at ƒ16 will capture more resolution than a 12mp camera shot at its sharpest ƒ-stop

QuoteOriginally posted by BigMackCam Quote
Now, I can't really see that difference when the image is downsized to fit - but it's there nonetheless..
This is why you have to put the ƒ-stop into context and how you are going to display the final image It is very easy to shoot a FF camera at ƒ22 and display it at 15-24mp and you won't see much in the way as diffraction
05-24-2022, 10:53 PM   #29
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QuoteOriginally posted by Ian Stuart Forsyth Quote
Yes at 1:1 that's why its important to have a ball park as to how the image is going to be display.
Diffraction limit often promotes the wrong idea as to how much one should stop down a lens. take a FF 36mp camera shot at ƒ16 will capture more resolution than a 12mp camera shot at its sharpest ƒ-stop.


This is why you have to put the ƒ-stop into context and how you are going to display the final image It is very easy to shoot a FF camera at ƒ22 and display it at 15-24mp and you won't see much in the way as diffraction
Agreed... if you know in advance that the image will only ever be viewed on a smartphone, a 15" laptop screen, or printed at small dimensions, diffraction is less of an issue; you can be somewhat cavalier in stopping down well into diffraction territory. There's an argument, though, that if you want to maximise your options for display (both medium and dimensions) - and, indeed, cropping (as you previously mentioned) - avoiding strong diffraction might be wise...

I have no issue with shooting at apertures where diffraction reduces detail, when appropriate. The intention with my film digitising is to capture as much detail in the negatives as possible (given the equipment I'm using), whilst maintaining just enough depth-of-field to allow for film that's not completely flat. I don't yet know for sure what I'll want to do with my digitised images... Most likely, the majority of them will only ever be viewed on one of my PC screens, but at some point I'll may have some of them printed, and it's just possible one or two of those prints might be larger - in which case I'll want to see all the detail in those images as rendered by the combination of the film camera's lens and the film medium, with minimum impact from the digitising camera and lens. As such, avoiding obvious diffraction at the digitising stage makes sense (to me, at least )...

Last edited by BigMackCam; 05-25-2022 at 05:09 AM.
05-25-2022, 01:27 AM   #30
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QuoteOriginally posted by marinb Quote
1. the image above is focus stacked from 2 images - one focus on top, one focus on paper's surface.
Sharp focus is a region that extends on both sides of the actual focus point, so you're wasting some of the sharpest focus regions both below the paper and above the powder. That means the part of your pile of powder halfway between the top surface and the paper is actually your least focused region.

Focus stacking more layers is always better, but at a minimum try adding a third image focused halfway between the paper and the top surface. If you must limit to two layers for processing time or workflow, try selecting points at about 25% and 75% of the total thickness you're interested in. That should help maximize the overall clarity of your focus stack.

(I stack microscope images where the depth of field is measured in microns and one extra layer can add 5-10 minutes of processing time, so I've had a lot of practice optimizing focus points for what I need to show.)

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