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10-10-2021, 01:28 AM   #16
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QuoteOriginally posted by biz-engineer Quote
That is the problem is classic DoF calculators being based on the goal of producing an acceptably sharp 8"x12" enlargement from a 35 film exposure. When I print, 24"x36", CoC of 28um is clearly too large.
I've found that for a bayer CFA type sensor, a two pixels wide CoC is realistic value (both conceptually, and what I could observe).
Unfortunately these "classic dof calculators" includes the dof scales on the old lenses.

10-10-2021, 02:43 AM   #17
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Depth of field is only a concept. The highest possible resolving power is at the plane of focus, and refocus blur is a largest contributor to resolution loss until lens aperture diffraction becomes the main contributor. The optimal f-number and focus distance are mostly not what's provided by calculators. For example, I shot a canyon picture with subject distance from 2m to 20m. The camera would set the lens to f11. But by taking into account sensor resolution, near and far distance and diffraction, the best setting was 28mm, f13, CoC = 0.013, focused at 3.8m, every other setting would provide less overall resolution. Other possible optimal setting would have been: FL = 24mm, f/11, CoC = 0.011, focus distance 3.8m. If lens aperture < 2 x pixel pitch , then use CoC = 2 x pixel pitch. If lens aperture > 2 x pixel pitch , then use CoC = f-number.

Last edited by biz-engineer; 10-10-2021 at 02:50 AM.
10-10-2021, 07:39 AM   #18
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QuoteOriginally posted by AggieDad Quote
I am curious if anyone is using hyper-focal distance when taking landscape and/or panoramas images.
Nope, not me. Hyper-focal is a fancy way of saying DOF that extends to the practical notion of infinity, something that may be much closer than one expects. Note that setting the distance scale on the lens infinity for a particular f-number on the DOF scale only provides hyper-focal focus within the limitations of the DOF scale (assumes 8x10" enlargement from 24x36mm frame viewed at 20"). For other formats or final magnifications, determining the hyper-focal distance requires calculation.

Thinking seriously about the question, I don't know that I use the calculated hyper-focal for anything.


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10-10-2021, 07:53 AM   #19
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QuoteOriginally posted by womble Quote
Many of my folders have a red dot on the focus ring and another on the aperture ring to indicate how to get the majority of the image sharp
Wide-angle Super-Taks, along with many K-mount wide-angles, have a similar "cheat" mark at f/8 with matching mark on the distance scale.


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10-10-2021, 12:35 PM   #20
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The is from the K Series lens manual:

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10-10-2021, 01:51 PM   #21
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Perhaps what one could do is to use the hyperfocal distance marks on the lens for f/8, but stop down to f/11 for “insurance.”


10-10-2021, 01:52 PM   #22
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QuoteOriginally posted by gofour3 Quote
The is from the K Series lens manual:

Phil.
Thanks for posting that. I learn something new every day! K.

10-11-2021, 02:42 AM   #23
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Has anyone knowledge about how field curvature of wide angel lenses has an impact on sharpness in infinity?
Is it advisable to focus on hyperfocal distance with a lens with strong field curvature? Shouldn't one just stop down to f=8 and hope the corners are sharp as well? Assuming all the subject is in infintiy, like in astrophotography for example.

I would be gratious if anyone had an explanation.
10-13-2021, 06:18 AM   #24
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I use it whenever I feel I need it, when I want things on different focal planes to be in focus. For me, it's just a tool in my toolbox. I didn't realize it was controversial

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10-13-2021, 07:36 AM   #25
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QuoteOriginally posted by womble Quote
As someone using manual lenses on film cameras often having no focusing aid, I use the scale on lenses frequently. Many of my folders have a red dot on the focus ring and another on the aperture ring to indicate how to get the majority of the image sharp. Even with 35mm I'll set the infinity mark to the set aperture on the focus ring to maximise depth of field.
My old film lenses had marks showing DOF for each aperture, so I would set aperture to around f/8 {f/5.6 for “APS-C” when I do it now}, then set the ‘high’ mark for that aperture to infinity ….. so DOF would cover everything from infinity down to as close to me as possible.
10-13-2021, 10:23 AM   #26
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I also miss many of the focus assistance tools common on older lens. However, they are not critical. One of the much used tools on my Super Program was the stop down lever. Several of the Pentax digital cameras do the same thing with the off-on-stop down dial around the shutter release.

My technique today is to use the center AF against the primary feature in my composition. That just gets me close to what I want. If the lens supports Focus Quick-Shift, I might use that (use the AF button in single mode to prevent focus change when you use the shutter release). Otherwise I switch to MF without changing the AF selected point. Then I use the stop down function and manually shift focus to the best compromise in the optical view finder. That compromise, may or may not require an aperture change with corresponding shutter and/or ISO change. It works well for any still life situation macro to landscape.
10-13-2021, 12:03 PM   #27
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QuoteOriginally posted by JimJohnson Quote
I also miss many of the focus assistance tools common on older lens. However, they are not critical. One of the much used tools on my Super Program was the stop down lever. Several of the Pentax digital cameras do the same thing with the off-on-stop down dial around the shutter release.

My technique today is to use the center AF against the primary feature in my composition. That just gets me close to what I want. If the lens supports Focus Quick-Shift, I might use that (use the AF button in single mode to prevent focus change when you use the shutter release). Otherwise I switch to MF without changing the AF selected point. Then I use the stop down function and manually shift focus to the best compromise in the optical view finder. That compromise, may or may not require an aperture change with corresponding shutter and/or ISO change. It works well for any still life situation macro to landscape.
I used to do similar, but I did begin to wonder how the AF/MF switch was rated for usage. I found myself switching back and forwards between AF and MF. This seemed daft. Why don't I just manual focus with LV (and a loupe)? Turns out it's easier for me for static subjects, both outside and in a studio setting.
10-14-2021, 09:28 AM   #28
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Well, I certainly received a lot of discussion in response to my little query. There seem to be a number of opinions about hyper-focal distance. Thanks to everyone for their thoughts.

For my own part, I think I will continue with my plan to add the calculation to my automated pano head, although @biz-engineer did raise possible questions about a usable value for the circle of confusion. I will have to do some more reading on that.

For me, the idea is simple. When my pano head system sets itself up with number of images, etc., it can show a hyper-focal distance on the display. I can choose to use it or not, depending on scene. It will be interesting to see how often I use it.
10-15-2021, 02:23 PM   #29
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QuoteOriginally posted by Bob 256 Quote
depending on what you need to capture and how much unsharpness you're willing to accept.
Focus stacking is a useful tool if you need a greater sharpness range.
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