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Aperture control + test script

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Offline reyalp

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Re: Aperture control + test script
« Reply #30 on: 15 / October / 2018, 14:00:31 »
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Quote from: c_joerg on 15 / October / 2018, 06:06:33
Where does the value of 1920 come from?
Arbitrary large value. I wanted to make the minimum at 0 and range syntax expects two values. If you have a lens that goes past f/1024, feel free to adjust it  :haha
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Offline c_joerg

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Re: Aperture control + test script
« Reply #31 on: 12 / November / 2018, 03:18:19 »
It is also very easy to determine with the script at which aperture a lens is the sharpest. In doing so, I simply created shots of a noisy picture. It is then sufficient to sort only the JPG images by size. The largest JPG is then the sharpest picture. I compared that to other methods. That's pretty good. The following plot shows the curves of a 50mm lens on the EOS M3. The first curve is the JPG size. Not sure if the Script could log the JPG size of the image.
More info
https://translate.google.de/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=https%3A%2F%2Ffotoschule.fotocommunity.de%2Ffoerderliche-blende-welche-blende-ist-meine-schaerfste%2F&edit-text=&act=url

Interestingly, the SX50 goes beyond aperture f8. The Canon Interfacce is only available until f8.
Code: [Select]
range=3.50-11.31 (347-672)

On high apartures the script delivers wrong values as I descript in Reply #27
Code: [Select]
range=6.44--24.-3 (516-1032)
« Last Edit: 12 / November / 2018, 03:20:09 by c_joerg »
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Offline c_joerg

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Re: Aperture control + test script
« Reply #32 on: 21 / November / 2018, 04:59:25 »
Maybe still interesting:

I have now not only evaluated the entire image, but also sometimes parts, so 10% of the image area from the middle or on the edge. Again, almost everything is explainable. The edges at the wide angle were always significantly worse than the telephoto.

However, there is an inconsistency with the combination EOS M3 and the EF 50mm f1.8 USM (to a lesser extent also with the EF 24mm f / 2.8 IS USM). If I only look at the center, then the lens reaches a maximum at f2.8, then gets a minimum at f4.5 and then gets a new maximum at f9. At f4.5, the edges are slightly sharper than the center. It makes no difference if I focus again before each shot or just once at the beginning. It is probably a Fokusshift that arises when closing the aperture.

For the 6D and EF 50mm f1.8 USM this does not happen in LiveView. When focusing, the aperture is also set on the 6D. I have never noticed that. I always thought, it is focused with an open aperture. The break in the sharpness in the center is then no longer available. Maybe that's why the S110 does not focus on open aperture.

Presumably there is no way with CHDK to close the aperture when focusing?
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Offline reyalp

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Re: Aperture control + test script
« Reply #33 on: 24 / November / 2018, 19:17:49 »
Quote from: c_joerg on 12 / November / 2018, 03:18:19
It is also very easy to determine with the script at which aperture a lens is the sharpest. In doing so, I simply created shots of a noisy picture. It is then sufficient to sort only the JPG images by size. The largest JPG is then the sharpest picture. I compared that to other methods. That's pretty good. The following plot shows the curves of a 50mm lens on the EOS M3. The first curve is the JPG size.
Good idea.
Quote
Not sure if the Script could log the JPG size of the image.
You can get the file name:
string.format('%s/IMG_%04d.JPG',get_image_dir(),get_exp_count())
and then get the size with os.stat

Quote
Interestingly, the SX50 goes beyond aperture f8. The Canon Interfacce is only available until f8.
Code: [Select]
range=3.50-11.31 (347-672)
Yes, most powershots work to somewhat higher f numbers than the UI max, and much higher when zoomed.
Quote
On high apartures the script delivers wrong values as I descript in Reply #27
Code: [Select]
range=6.44--24.-3 (516-1032)
This should be fixed in trunk 5126. I don't think any powershots get close f/32 but maybe you could put something on the Ms that does.

Quote
For the 6D and EF 50mm f1.8 USM this does not happen in LiveView. When focusing, the aperture is also set on the 6D. I have never noticed that. I always thought, it is focused with an open aperture. The break in the sharpness in the center is then no longer available. Maybe that's why the S110 does not focus on open aperture.
I wonder if this depends on available light. With good light, then using the same aperture as the shot should be best, but at some point the SNR probably matters more?

Quote
Presumably there is no way with CHDK to close the aperture when focusing?
If setting CHDK overrides doesn't, then probably not. Hooking into the AF process could be useful, but I'm not aware of any work in that area. One thing I'd love is to be able to limit the range of the AF scan, so if you are shooting far away it can just sweep say 100m+ instead of the whole range.
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Offline c_joerg

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Re: Aperture control + test script
« Reply #34 on: 25 / November / 2018, 03:28:45 »
Quote from: reyalp on 24 / November / 2018, 19:17:49
This should be fixed in trunk 5126. I don't think any powershots get close f/32 but maybe you could put something on the Ms that does.
Thanks a lot I've just tested it works really well. Of course there will always be some f-stops on the M's but higher values do not really make sense anymore.
Quote from: reyalp on 24 / November / 2018, 19:17:49
I wonder if this depends on available light.
It's hard to say how far that depends on the available light. The aperture on the S110 is already very small to determine that. It does not work on the real aperture but only fades something off.
It's the same with the 6d. It does not completely go to the selected aperture. It looks like the aperture is only a little bit closed, may be enough to avoid the focus shift. That seems to be so even in low light. In the case of a lot of light, it seems to dazzle much more in the live view and to be easily opened when focused.
Quote from: reyalp on 24 / November / 2018, 19:17:49
With good light, then using the same aperture as the shot should be best, but at some point the SNR probably matters more?
From a certain aperture, the depth of field is probably so big that the camera no longer finds maximum
Quote from: reyalp on 24 / November / 2018, 19:17:49
If setting CHDK overrides doesn't, then probably not.
In the M3, I have a button with which I can control the depth of field. When I press the button, the camera goes to working aperture. What could be behind it? Could I search for a function in the firmware?
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