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Aperture control + test script

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Offline reyalp

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Re: Aperture control + test script
« Reply #10 on: 11 / September / 2018, 23:13:07 »
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I’m wondering why ISO increases every shoot in quick mode. Maybe it has something to do with the setting of ISO here (the difference of 1).
Yeah, looks like that plus sloppy coding on my part. I've updated the script in the first post to not touch the ISO if the camera is already in manual ISO mode, and when it does control ISO use the value from the initial half press rather than the last value read from the propcase.
Don't forget what the H stands for.

Re: Aperture control + test script
« Reply #11 on: 12 / September / 2018, 12:10:10 »
Another run with G1x in Quick mode. Looks like G1x has more noise in m96_err as G7x…

Re: Aperture control + test script
« Reply #12 on: 12 / September / 2018, 12:40:08 »
Did a run with M3 in all 3 modes (Quick, Cont, Single). I used EF50mm 1:1.8 STM lens.
Get_min_av96 returns a nil value on M3 so I set values from 200 to 600 (may be max as well).
Locks like all 3 modes are working!

There is a big noise in m96_err and some warnings in log files. The warnings came from the big difference?

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Offline reyalp

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Re: Aperture control + test script
« Reply #13 on: 12 / September / 2018, 13:47:01 »
Did a run with M3 in all 3 modes (Quick, Cont, Single). I used EF50mm 1:1.8 STM lens.
Get_min_av96 returns a nil value on M3 so I set values from 200 to 600 (may be max as well).
Locks like all 3 modes are working!
Good to know. Perhaps available AV range can be found though other functions on EOS cameras.

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There is a big noise in m96_err and some warnings in log files. The warnings came from the big difference?
Yes, all the warnings were from "high error" which is arbitrarily set to > 6 APEX*96 units.

Interestingly, your error does not appear to be random: The 4th, 7th, 10th and 11th all have high error, but across runs are within 2 units.

"error" is simply the meter96 difference from the previous shot compared to the expected value. With "constant exposure" shutter speed is adjusted to compensate for the Av change so the expected value is the previous value.
Don't forget what the H stands for.


Re: Aperture control + test script
« Reply #14 on: 13 / September / 2018, 02:58:32 »
Interestingly, your error does not appear to be random: The 4th, 7th, 10th and 11th all have high error, but across runs are within 2 units.

It probably depends on how far the set value is away from a whole aperture. I have not tested smaller steps yet.

As you can see in this video, I would expect greater deviations in the adjustment of the aperture. Interestingly,
this does not seem to be the case with the G7x.


Re: Aperture control + test script
« Reply #15 on: 13 / September / 2018, 05:50:42 »
Why AV96=200 delivers f2.59 in the log file? f2.06 should be Ok
AV96=232 delivers f2.311 which looks OK

Looks like av96_to_aperture is limited from f2 to f16.
What delivers the G7x at f1.8?
It’s time to extend av96_to_aperture from f1.2 to f32….

I was looking at implementation of av96_to_aperture. Implementation in C is different as in hostlua functions. Why?

« Last Edit: 13 / September / 2018, 07:51:34 by c_joerg »

Re: Aperture control + test script
« Reply #16 on: 13 / September / 2018, 12:14:31 »
I made 4 runs in quick mode with 4 different lenses
(logging of focal length would help to identify them):
EF 50mm f1.8 USM
EF 24mm f/2.8 IS USM
EF-S 55-250mm f/4-5.6 IS STM at 55mm
EF-M 15-45mm f3.5-6.3 IS STM at 15mm
Only the native EF-M lens didn’t open the aperture between shots. All other lens always gets open between the shoots. I expected less noise in m96_err but I can’t see it.

Re: Aperture control + test script
« Reply #17 on: 13 / September / 2018, 12:50:07 »
Another 2 runs in quick mode with 2 different lenses. 50 shoots and step of 4.
EF 50mm f1.8 USM
EF-M 15-45mm f3.5-6.3 IS STM at 15mm
It works very well but I have definitely to deflicker a time-lapse scene…


Re: Aperture control + test script
« Reply #18 on: 13 / September / 2018, 13:26:53 »
Last run for today  :)
G1x with step size 1. More noise at G7x but less than M3…

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Offline reyalp

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Re: Aperture control + test script
« Reply #19 on: 13 / September / 2018, 17:37:14 »
Why AV96=200 delivers f2.59 in the log file? f2.06 should be Ok
Oops, that's a formatting error on my part. It should be 2.05[9]. All the calculation and exposure control is done in APEX*96, so this should only be a log issue.

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I was looking at implementation of av96_to_aperture. Implementation in C is different as in hostlua functions. Why?
Presumably someone didn't want to figure out how to do it in integer-only hostlua.

The CHDK C implementation should be correct, and should work for anything over f/1.0. We should probably support f/1.0 and below now that we have ILC cameras...

G7 X works correctly from f/1.8

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It works very well but I have definitely to deflicker a time-lapse scene…
If the error has a repeatable component it would be relatively easy to come up with a correction table and apply the difference in Tv.

A better way to measure error might be to take several shots at a fixed value, and then compare subsequent to the average. In the current script, the accuracy of the previous shot can significantly affect the error reported.
Don't forget what the H stands for.

 

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