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SX40: AutoISO above ISO800?

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Offline philmoz

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Re: SX40: AutoISO above ISO800?
« Reply #10 on: 15 / March / 2012, 20:46:17 »
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By the way, it would be great if the step in varying the ISO value would be in multiple of 10s... takes about 30 sec or so of holding the right button down to go from 800 to 2000 :)

Use the zoom lever to change the increment value (shown at the top of the menu).

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)

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Offline blackhole

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Re: SX40: AutoISO above ISO800?
« Reply #11 on: 16 / March / 2012, 03:46:22 »
Was increasing the max auto ISO from 800 to 2000 the only change that you made?

Yes

Try to use the P mode, I do not know what to say.

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Offline longtalker

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Re: SX40: AutoISO above ISO800?
« Reply #12 on: 16 / March / 2012, 06:29:00 »
Quote
Use the zoom lever to change the increment value (shown at the top of the menu).
Phil.
Thanks Phil, that's really ingenious and useful to know!

Quote
Try to use the P mode, I do not know what to say.
Seems to be the same for the P mode, however it is really in the HQ mode where it is important to be able to use the Auto ISO to the whole width of its range (100-3200 in Canon values). It's strange that, with the upper limit of the auto ISO set to 800 (the old CHDK build), the camera never selects an ISO higher than 400, even in very low light, whereas with your build, although you can select an upper limit of 2000, the camera only selects ISOs as high as 800.

Phil, do you reckon there'll be a future build that corrects this?...

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Offline blackhole

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Re: SX40: AutoISO above ISO800?
« Reply #13 on: 16 / March / 2012, 10:20:33 »
Why do you use Max AutoISO function if you want your camera uses high values?AutoISO function is precisely to limit the upper values.
Set the ISO to AUTO in the menu of the camera and you gonna use all the values.


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Offline longtalker

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Re: SX40: AutoISO above ISO800?
« Reply #14 on: 16 / March / 2012, 20:38:51 »
I want the camera to select the lowest ISO for which my minimum exposure speed (e.g. 1/15s) can be used. In the High Speed Burst HQ mode the camera doesnt allow you to set your ISO unfortunately, only auto ISO. Left on its own, the camera always selects ISO800, even when there's plenty of light. So you need CHDK to impose the lowest ISO override that I described above.

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Offline philmoz

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Re: SX40: AutoISO above ISO800?
« Reply #15 on: 16 / March / 2012, 22:34:34 »
Phil, do you reckon there'll be a future build that corrects this?...

Try revision 1739 when it gets loaded onto the autobuild server.

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)

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Offline longtalker

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  • SX40 1.00F
Re: SX40: AutoISO above ISO800?
« Reply #16 on: 17 / March / 2012, 10:06:38 »
Thanks so much Phil, I just installed revision 1747 (which I assume includes the changes that you made into revision 1739), however the auto ISO in HQ mode still doesn't seem to work as expected:

- the camera never selects an ISO higher than 400, even in low light. The first time after starting the camera with the new build, it selected high ISOs that corresponded to an unnecessarily fast exposure, but after taking some pics/restarting the camera, it now does the ISO/exposure speed trade-off correctly (i.e. ISO not higher than necessary), but never exceeds ISO 400

- I took some pictures in moderate light conditions, in HQ mode, and even though at half-press the exposure seemed to be 1/8 (my set minimum exposure speed) at ISO100, when viewed in play mode, those picture were all over-exposed, with the real exposure time probably being slower although the EXIF said 1/8; the exact same scene taken in P mode at ISO100 had recommended exposure 1/15. I know about the difference between real and Canon ISO values, however even so I would have thought that whatever ISO is selected, the recommended exposure is the one appropriate for the scene. I tried the old version again (1692), and that one works correctly, in the sense that the same scene photographed in HQ mode (with auto ISO that resolves to ISO 100) and P mode at ISO=100, will lead to identically exposed images, as expected.

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Offline longtalker

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Re: SX40: AutoISO above ISO800?
« Reply #17 on: 17 / March / 2012, 13:37:04 »
Slightly off-topic, I might also mention a minor bug: whenever I go into MF and use the subject distance bracketing, Zebra mode turns itself on, even though I always have it off. If I then turn it off, it will stay off until the next time that I use CHDK's focus bracketing feature.


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Offline philmoz

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Re: SX40: AutoISO above ISO800?
« Reply #18 on: 17 / March / 2012, 23:52:34 »
Thanks so much Phil, I just installed revision 1747 (which I assume includes the changes that you made into revision 1739), however the auto ISO in HQ mode still doesn't seem to work as expected:

- the camera never selects an ISO higher than 400, even in low light. The first time after starting the camera with the new build, it selected high ISOs that corresponded to an unnecessarily fast exposure, but after taking some pics/restarting the camera, it now does the ISO/exposure speed trade-off correctly (i.e. ISO not higher than necessary), but never exceeds ISO 400

- I took some pictures in moderate light conditions, in HQ mode, and even though at half-press the exposure seemed to be 1/8 (my set minimum exposure speed) at ISO100, when viewed in play mode, those picture were all over-exposed, with the real exposure time probably being slower although the EXIF said 1/8; the exact same scene taken in P mode at ISO100 had recommended exposure 1/15. I know about the difference between real and Canon ISO values, however even so I would have thought that whatever ISO is selected, the recommended exposure is the one appropriate for the scene. I tried the old version again (1692), and that one works correctly, in the sense that the same scene photographed in HQ mode (with auto ISO that resolves to ISO 100) and P mode at ISO=100, will lead to identically exposed images, as expected.

Not sure what else to try - it works fine on mine, it will select ISO up to 3200 in normal mode and 1250 in HQ burst.
The fix in 1739 sorted out the overexposure issue for me.

Phil.

CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)

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Offline philmoz

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    • Photos
Re: SX40: AutoISO above ISO800?
« Reply #19 on: 17 / March / 2012, 23:56:59 »
Slightly off-topic, I might also mention a minor bug: whenever I go into MF and use the subject distance bracketing, Zebra mode turns itself on, even though I always have it off. If I then turn it off, it will stay off until the next time that I use CHDK's focus bracketing feature.

In ALT mode if you half press the shutter, and then press the left key (with the shutter half pressed) it will toggle zebra mode.

I've not had any instance of zebra being enabled when using bracketing.

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)
  g7x2 (1.01a, 1.01b, 1.10b)

 

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