[biz-engineer]

Could you recommend a suitable loupe to view these images at dot pitch resolution? – I feel somehow I'm missing out on proper evaluation of monster prints.

Yes, I have two: one is x15 (I can see the dots of the inkjet printer, I can also see the laser steps of the light-jet machine), the other one is x 2 and x 5. I'm not using any of these for looking at a 40"print, I'm standing 20" away, and I can't see any pixel at all, but I do see diffraction blur at f10, it looks like a test print I made at 125 PPI. => half of pixels are wasted

---------- Post added 22-04-20 at 22:08 ----------

The issue isn't whether the OP's desires are achievable (clearly they are), but that he's expecting to achieve them with his current equipment (which isn't going to happen)

I don't know. I'm thinking about how far I can stretch my system , since I'm not going to spend 50K Euros into a Phase One system. For example it came to my mind that I could do aperture brackering: take 4 shots of the same scene at f5.6, f8, f11, f16. The f16 increase the DoF to give me the foreground in focus (with some amount of diffraction). The f11 narrows a bit DoF but decrease diffraction of f16 where f11 is in focus. etc... etc... Since my camera hasn't moved for each of the 4 shots, I should have to layer them and mask portions of frames depending on DoF and f number. I can combine with pixel shift. So in the center I max out sharpness, in the foreground sharpness is not the best but better than if it was out of focus.

---------- Post added 22-04-20 at 22:14 ----------

Some ideas given in this thread are worth considering, such as tilting the camera forward. That's one option. It good to understand options and limitation, so that we have more choices in the field.

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Last edited by biz-engineer; 04-22-2020 at 01:15 PM.

[BigMackCam]

I don't know. I'm thinking about how far I can stretch my system , since I'm not going to spend 50K Euros into a Phase One system.

Then your best option is focus stacking - to which I'll add, a lens with a fairly flat field would be advantageous here.

The tilt lens option is an interesting possibility too, but won't be suitable for every type of scene since you'd be altering the plane of focus, not increasing the depth of field for the whole frame...

Beyond that, my congratulations - you have successfully stretched your system as far as possible for this particular application

[pschlute]

Many artists rely on technical perfection for the artwork to stand

So does this mean that before Pixel shift a great shot could not be achieved on a DSLR, and one had to use large format like Hofer ?

I believe too many photographers today are fixated on sharpness in an image.

[biz-engineer]

Then your best option is focus stacking - to which I'll add, a lens with a fairly flat field would be advantageous here.

Focus stacking is a workaround diffraction like lens tilt. However, as I mentioned, when I tried to focus stack and stitch , it didn't work.


If I do aperture bracketing, there is no focus breathing involved. And I can still stitch. Since aperture bracketing was removed by Ricoh since the K3 (Pentax added automatic aperture bracketing on the K5), I need to use my phone with image sync to change the aperture without touching the K1, it also works with pixel shift.


The other thing that seems to work is to capture exposures of a panorama composite and refocusing the lens. The focal length changes at every shot (focus breathing), but it seems that Hugin is able to deal with variations of focal length. Then the issue is to about blur area in the stitched panorama, it can be done by having a lot of overlap between frames.

---------- Post added 22-04-20 at 22:31 ----------

So does this mean that before Pixel shift a great shot could not be achieved on a DSLR ?

Possibly because view cameras continued to be used by a number of artists long after the market of digital camera became the dominant market. Even today, some professionals still use 4x5 or 8x10 film cameras, especially the ones who can't afford a Phase One 150Mp or when full frame resolution is insufficient. I've read that Clyde Butcher is now using a digital camera (Sony A7R) but he is shifting the Sony A7R mounted at the back of a Cambo Actus in combination with his large format lenses.

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Last edited by biz-engineer; 04-22-2020 at 01:33 PM.

[house]

So does this mean that before Pixel shift a great shot could not be achieved on a DSLR ?

I think you need to read the whole of the post you are quoting. There was another example photo. For the record I think a great shot can be achieved on any piece of kit but all shots can not be achieved on all kit. The argument that a blurry subject is detrimental to a photo is as bad as the argument that technical perfection is detrimental. It depends on what it is you want to do.

Of course there is a valid and interesting discussion to be had about what subjects and expressions can have real meaning today but this forum is not the place for that discussion.

[photoptimist]

Why can't pictures just be beautiful?
Over-analysis is the death of art.

That same "over-analysis" also contributes to the birth of art! I've known many an artist was was amazingly technical because getting the most out of a medium means really understanding how that medium works.

Some of use want to understand why some pictures are beautiful (whether sharp or blurry) and why some aren't (whether too sharp or too blurry). We want to understand the confluence of the neurobiology of human vision and the refractive physics of glass to understand how to make the viewer of a photograph see what the photographer wanted them to see using the equipment at hand. We'd like technical mastery over the medium so we can create beauty with more reliability than the typical spray-and-pray camera user does.

Maybe what we are talking about in this thread is just one of the many diverse paths to art or communication or whatever it is that each of us wishes to accomplish with our images. As just one of many path to art, some may find these technical digressions to be dry, enervating, and worthless. But others may find them thought provoking, enlightening, and quite valuable.

[BigMackCam]

Focus stacking is a workaround diffraction like lens tilt.

Every approach is going to be a workaround of one sort or another, since no lens for a large sensor is going to give you sufficient depth of field. Even Clyde Butcher's use of camera / lens movements is a workaround to address this very problem. The tilt lens I suggested is the closest to his approach, albeit more limited in the range of movements.

However, as I mentioned, when I tried to focus stack and stitch , it didn't work.

That doesn't mean it can't work. Since you're wanting to stretch the capabilities of your existing system as far as possible, it seems further experimentation here is worthy of your time. Have you deduced why it didn't work? Did the stacking of individual sections work OK? Did you try stitching just a single pair of stacked frames at a time to see if it was failing on a specific portion of the composite? What focal length and aperture were you shooting with? Does the lens have a relatively flat field? Did you take sufficient shots at each focal distance to ensure sufficiently sharp results across the frame (specifically in the borders)? Did you leave sufficient overlap between sections for the stitching software to work properly? Did you properly correct distortion in every frame shot?

If I do aperture bracketing, there is no focus breathing involved. And I can still stitch. Since aperture bracketing was removed by Ricoh since the K3 (Pentax added automatic aperture bracketing on the K5), I need to use my phone with image sync to change the aperture without touching the K1, it also works with pixel shift.

I don't understand how aperture bracketing would help with increased depth of field... Could you briefly explain your approach?

[biz-engineer]

Every approach is going to be a workaround of one sort or another, since no lens for a large sensor is going to give you sufficient depth of field. Even Clyde Butcher's use of camera / lens movements is a workaround to address this very problem. The tilt lens I suggested is the closest to his approach, albeit more limited in the range of movements.

That's what I meant. Lens / camera tilt is an extra effort (what I called workaround) to have the whole image in focus , while it would only be possible to have the whole image in focus with lots of diffraction without the tilt. Tilt or focus stack are both extra steps taken to go pushed back the negative impact of diffraction.

---------- Post added 22-04-20 at 23:06 ----------

Have you deduced why it didn't work?

I believe focus stacking and pano stitching didn't work because each operation is done by a different software. After focus stacking is done, the stitcher tries to stitch images using lens type of distortion not knowing that the image was distorted by the focus stacker. The stitcher expect images from a camera , not images modified by a focus stacking operation. I tried a few times and I gave up.

[BigMackCam]

I believe focus stacking and pano stitching didn't work because each operation is done by a different software. After focus stacking is done, the stitcher tries to stitch images using lens type of distortion not knowing that the image was distorted by the focus stacker. The stitcher expect images from a camera , not images modified by a focus stacking operation. I tried a few times and I gave up.

Have you tried stitching the images for each focal distance first (after applying the same lens corrections to each shot, of course), then stacking the resulting frames?

[biz-engineer]

I don't understand how aperture bracketing would help with increased depth of field... Could you briefly explain your approach?

Aperture bracketing would be a partial approach. If use my 100 macro lens for wide angle panorama, I need to stop down the lens to f16 (for example) due to the 100mm focal lens DoF is reduced, so I need to stop down the lens as if I was shooting with a 4x5 camera. With f16, my 5um K1 pixels are blurred by diffraction, so f16 improves my DoF but destroys my resolution. If I use f8, the center of the image (focus with center point) is in focus and not so much affected by diffraction, but the outer part of the image is out of focus. If I blend the f16 image with the f8 image, I can keep the center of the frame from the f8 image and the replace the out of focus part of the image by the f16 frame parts. Doing so, I avoid diffraction in the most in focus image aera, and I let more diffraction be in regions where focus is not as good. This avoid to have diffraction hit 100% of the frame.

Practical example: I have a big rock in the foreground with lots of pixels to define that rock, and I have small trees far away in the distance with few pixels to define tree branches. I take one shot at f16 to get the rock in focus, the tree in the distance looks fuzzy due to pixel level diffraction. I take an other shot at f8, the rock in the foreground is OOF, but the tree detail is sharp. I blend the two images to keep the rock in the foreground from the f16 exposure, and keep the tree in the distance from the f8 exposure. This is not focus stacking since changing the lens aperture doesn't change the focal length of the lens, refocusing the lens in case of focus stacking would due to focus breathing.

[swanlefitte]

That same "over-analysis" also contributes to the birth of art!

Very true.
The Mona Lisa is very technical but it is famous for being stolen😜. Monet for his technical study of light. It is a high level of understanding that allows for a new way of using the medium. Indeed rules od composition are based on technical aspects. Everyone else just produces the same thing.
Lewis Carrol agreed that the science made it worthy. Somebody let the rabble in. The technically happy were doing photography with wet plate. Yet the influx of photographers with dry plate shows most don't want to be bothered.

[biz-engineer]

Have you tried stitching the images for each focal distance first (after applying the same lens corrections to each shot, of course), then stacking the resulting frames?

Yes. I've tried that. So I get two panoramas that should be focus stacked. The stitching software use control points that are sharp details (avoid clouds for example) to make use frame alignment is accurate. Since the focus is not the same for one pano compared to the other, the stitching software doesn't use the same control points to create each panorama. So when you try super-impose those two panorama they don't match.

[MJKoski]

That aperture bracketing thing does actually work. I have used it few times in the same manner - to get "sharp" areas around the critically sharp primary subject in a landscape scene. It is useful in another technique as well - sometimes trying to focus stack with a telephoto lens the foreground may have parts which cover other distant parts of the image. Then, even the best focus stacking software will have problems trying to blend in the foreground with the background when large aperture is used. But if one stops down enough for the foreground parts, it will ease the blending job for the stacking software.

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An example of aperture bracketing with focus stacking:



Here I used 100mm WR Macro to take a good bunch of f/5.6 exposures at different focusing distances closing the aperture down towards f/11 when focusing got closer to camera. There are no foreground parts covering background areas but stopping down more towards close distance radically lowered the amount of exposures needed. Helicon Focus was used to stack the exposures.

[BigMackCam]

Aperture bracketing would be a partial approach. If use my 100 macro lens for wide angle panorama, I need to stop down the lens to f16 (for example) due to the 100mm focal lens DoF is reduced, so I need to stop down the lens as if I was shooting with a 4x5 camera. With f16, my 5um K1 pixels are blurred by diffraction, so f16 improves my DoF but destroys my resolution. If I use f8, the center of the image (focus with center point) is in focus and not so much affected by diffraction, but the outer part of the image is out of focus. If I blend the f16 image with the f8 image, I can keep the center of the frame from the f8 image and the replace the out of focus part of the image by the f16 frame parts. Doing so, I avoid diffraction in the most in focus image aera, and I let more diffraction be in regions where focus is not as good. This avoid to have diffraction hit 100% of the frame.

Practical example: I have a big rock in the foreground with lots of pixels to define that rock, and I have small trees far away in the distance with few pixels to define tree branches. I take one shot at f16 to get the rock in focus, the tree in the distance looks fuzzy due to pixel level diffraction. I take an other shot at f8, the rock in the foreground is OOF, but the tree detail is sharp. I blend the two images to keep the rock in the foreground from the f16 exposure, and keep the tree in the distance from the f8 exposure. This is not focus stacking since changing the lens aperture doesn't change the focal length of the lens, refocusing the lens in case of focus stacking would due to focus breathing.

Thanks for the explanation That's an interesting and rather clever approach.

I'd have thought it's a lot of work to successfully blend such that on close inspection, the guy with his nose a couple of inches isn't able to see the transitions. But if it gets you where you wanna go, awesome!

[biz-engineer]

I'd have thought it's a lot of work to successfully blend such that on close inspection, the guy with his nose a couple of inches isn't able to see the transitions. But if it gets you where you wanna go, awesome!

Well, 40x 60" posters framed on canvas shot with 22Mpixels are easy to find at Ikea and Amazon, you can have one for 39 euros or less. No need to go through the effort of using a Pentax camera and going through the creation of the photographs, post processing , ordering it to a photolab and framing it. However, the prints shot on Phase One that are sold by Lumas in Berlin, Paris and Vienna sell at prices from 3500 euros to 8000 euros each. The price for a 40 x 60" C-print on high end paper (from the same lab as the one working for Lumas) costs me between 100 and 200 euros, so you can see my stitching and stacking effort could be worth several thousand euros.