M4/3 at F8 and beyond???

archaeopteryx

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Plus the info provides a good support for your original premise that f/4 - f/5.6 is the sweet spot.
I should probably caution 12 mm on m43 is kind of a special case among ILCs. As always, one can choose different analysis approaches. But the hyperfocal distance is a common starting point for everything in focus landscape photography. Within this discussion, probably most the interesting parameter is where the near focus distance falls for a given an aperture, focal length, and circle of confusion. Taking the circle of confusion to be the pixel size yields the figure below, the main point being the near focus distance increases with the square of the focal length. So for example, while f/5.6 works well with the style of the 12 mm example photograph above, if one wanted to make the same use of the sensor at 25mm on m43 you'd need to stop down past f/22 and then remove over four stops' diffraction. That has the small problem of being really hard.
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There are a couple other things I find interesting here. One is, looking across the formats, m43 and smaller aren't diffraction limited at the equivalent of 12mm f/5.6 whilst the additional MP of larger sensors puts them into diffraction. For the oft-cited 1-2 stop differences between m43 and APS-C and full frame to apply the number of MP has to stay constant. Which, personally, kind of defeats the purpose of hauling around larger, heavier, more expensive kit. The other is the phones I've used lack an aperture control, which makes their hyperfocal near focus distances a bit longer. It happens I do a lot of wide documentary images and this contributes to deciding when to get out the G7 versus using my phone.
 
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Giiba

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I should probably caution 12 mm on m43 is kind of a special case among ILCs. As always, one can choose different analysis approaches. But the hyperfocal distance is a common starting point for everything in focus landscape photography. Within this discussion, probably most the interesting parameter is where the near focus distance falls for a given an aperture, focal length, and circle of confusion. Taking the circle of confusion to be the pixel size yields the figure below, the main point being the near focus distance increases with the square of the focal length. So for example, while f/5.6 works well with the style of the 12 mm example photograph above, if one wanted to make the same use of the sensor at 25mm on m43 you'd need to stop down past f/22 and then remove over four stops' diffraction. That has the small problem of being really hard.
There are a couple other things I find interesting here. One is, looking across the formats, m43 and smaller aren't diffraction limited at the equivalent of 12mm f/5.6 whilst the additional MP of larger sensors puts them into diffraction. For the oft-cited 1-2 stop differences between m43 and APS-C and full frame to apply the number of MP has to stay constant. Which, personally, kind of defeats the purpose of hauling around larger, heavier, more expensive kit. The other is the phones I've used lack an aperture control, which makes their hyperfocal near focus distances a bit longer. It happens I do a lot of wide documentary images and this contributes to deciding when to get out the G7 versus using my phone.
We seem to have killed the conversation with science...

But I am enjoying these graphs immensely, so I'll keep chatting. I see your point about a sweet spot at 12mm, and see justification for the choice of f/22 on m4/3 lenses. Really at that aperture your no worse off than a top end FF camera.

I think the question to bring us back into the original intention of this thread would be: is there a way to compare the resolution between a picture at a given aperture vs a stacked affair at larger aperture.

Or at what point in stopping down for added DOF are you better off to focus stack?
 

50orsohours

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We seem to have killed the conversation with science...

But I am enjoying these graphs immensely, so I'll keep chatting. I see your point about a sweet spot at 12mm, and see justification for the choice of f/22 on m4/3 lenses. Really at that aperture your no worse off than a top end FF camera.

I think the question to bring us back into the original intention of this thread would be: is there a way to compare the resolution between a picture at a given aperture vs a stacked affair at larger aperture.

Or at what point in stopping down for added DOF are you better off to focus stack?
99.99% of the time when I’m out on a walk or hike, I’m with my wife. Which means a lightning fast stop and then running to catch up with her. So stacking, most of yeh time is out of the question. But, the rest of the time, for the type of landscape that we are surrounded by, I will stack at F4. Every single time. But I do get it, that if one doesn’t print, or print large, it maybe a waste of time.
 

archaeopteryx

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Or at what point in stopping down for added DOF are you better off to focus stack?
If you need 1/30 or faster for stopping subject motion then with current technology it's going to be stop down, maybe up ISO, and (if you're pushing limits) do diffraction removal and noise reduction in post. For optimal stacking it's straightforward maths (though I suggest the more accurate form over conventional DoF formulae which give negative DoF at close focus).

In the 12 mm case we've been considering, stacking two optimally spaced frames slightly exceeds the near focus of f/11 hyperfocal (1.93 vs 1.96 m) and stacking four frames is similar with f/22 (96 vs 98 cm near focus). Whether stacking is faster than a stopped down exposure depends on the time the lens takes to move to the next focus position, shutter speed, frame rate, ISOs used, and how closely the camera can be configured to focus bracket at the optimal distances. With current implementations bracketing is probably not going to be optimally sequenced and therefore has a good chance of taking longer. This increases the potential for motion blur of the subject and, when there's enough light, some of the stopping down can be "free" in the sense that one continuous exposure keeps the shutter open during what would be unexposed time between bracketed frames.

Results are structurally the same at 25 mm with increasing focus distances and decreasing depth as one would expect. Other factors held constant, DoF decreases essentially with square of focal length. I didn't plug in the bracketing distances below 1.59 m as it's a tedious way to produce a cluttered figure but one can see the corresponding squared increase in the number of frames to stack emerging.
m43 hyperfocal stacking.png
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If one's interested in stacking at f/4 or some other aperture the behavior's not much different. Probably the main things be aware of, however, are the cropping, reduction in MP, and increased encoding loss of 4k frame extraction relative to focus bracketing. Nearly all my 4k stacking is in macro, where considerations are rather different, but to the limited extent I've compared my sense is stopping to f/16 or 22 and deconvolving can be competitive with a 4k stack on image quality as well as speed in the field. Lots of potential for variation with software in post.
 
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ralf-11

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at f/22 how much diffraction is there - relative to the out of focus blur at f/8 at distance x???

x is measured as a distance from the plane of focus
 

archaeopteryx

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That's kind of an interesting question. Here's one way of showing the lens (f²/N) part of it (the diffraction bit having been covered over the last couple pages).
12mm blur.png
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25mm blur.png
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EDIT: Some additions due to discussion elsewhere.
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ralf-11

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I thought the question was interesting b/c it is exactly what we want to know, right?

We care about diffraction because of unsharpness.
 

archaeopteryx

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it is exactly what we want to know, right?
Well, I'd say more it is exactly what defines the problem.

Another way of putting my remarks above is I chose m43 in part because it's arguably an optimal f²/N tradeoff under current and likely near future sensor pixel densities if one's doing (ultra)wide everything in focus landscape stuff. Which is something I commonly do. In part, it's also because Panasonic and Olympus have lacked Canon, Sony, and Nikon's incentives to block features such as focus bracketing on lower cost bodies to encourage full frame purchases.

I'm curious where Panasonic is going to go with L mount DFD. Partially for positioning features in future bodies but mostly because DFD relies on knowing point spread functions across the entire sensor in real time. So Panasonic has industry leading potential for deconvolving diffraction. And, if the diffraction compensation in my G7 is anything to go by, they're not using any of it. :rolleyes-38: In lieu, it's a little silly current diffraction removal methods in post are spatially invariant even though PSFs are spatially variant. (Though piccure+, being mostly but not entirely dead, is an exception.)
 
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