Automatic IS Disable/Enable

fudgey

1705
a570is

« on: 13 / July / 2008, 04:43:48 »

Advertisements

Some of this has been discussed before somewhere, but all I could find in feature requests was one for an IS on/off shortcut key.

As we know, IS (image stabilizer) should not be used for long exposures on a tripod, because it may cause spurious sensor motion, resulting in blur.

Now, it would be neat if CHDK had an option to temporarily disable IS whenever shutter speed is slower than a user specified value (default could be >1 second or whatever is the slowest Tv autoexposure will ever give).

Even neater would be to disable IS -- no matter which shutter speed -- when the IS sensors reveal that the camera hasn't been significantly moved for a second or two (i.e. "tripod detection"), and re-enable it immediately when camera motion is detected. This might actually cut power consumption a little bit as well.

Logged

Aged

Re: Automatic IS Disable/Enable

« Reply #1 on: 13 / July / 2008, 06:16:42 »

A couple of notes which may be relevant
IS operated by half shoot available 0.5 sec later (IS_lens_booklet pdf Canon web site)
Panorama (stitch mode) probably switches off one of the stabilizing gyros (comparison review of Nikon and Canon methods)

Logged

LjL

266
A720IS

Re: Automatic IS Disable/Enable

« Reply #2 on: 13 / July / 2008, 07:33:14 »

For your second request (automatic tripod detection), you need functions that are currently only available in DataGhost's build. I think I will look at the possibility.

The simpler request to disable it below a certain shutter speed should be doable in trunk...

... except I absolutely cannot find any function, in the currently published stubs (including DataGhost's), that would set the IS mode. PROPCASE_IS_MODE appears to be read-only, so unless you're willing to have this simulated by keystrokes (with the unpleasant result if seeing the menu flash up while you're fidding with shutter speeds), you'll need someone who's familiar with inspecting the firmware's code, to get this implemented.

Logged

fudgey

1705
a570is

Re: Automatic IS Disable/Enable

« Reply #3 on: 13 / July / 2008, 08:44:20 »

Quote from: LjL on 13 / July / 2008, 07:33:14

For your second request (automatic tripod detection), you need functions that are currently only available in DataGhost's build. I think I will look at the possibility.

Yep, I'm aware of this. And I believe this code hasn't been ported for many models yet. Just giving one more reason for people with IDA and the skill to look into it one day

...and in the process I hope that camera vendors read our feature requests and implement some of them in their firmware. And with the hope that there remains previous art on the internet to prevent patenting the obvious.

Quote from: LjL on 13 / July / 2008, 07:33:14

The simpler request to disable it below a certain shutter speed should be doable in trunk...

... except I absolutely cannot find any function, in the currently published stubs (including DataGhost's), that would set the IS mode. PROPCASE_IS_MODE appears to be read-only, so unless you're willing to have this simulated by keystrokes (with the unpleasant result if seeing the menu flash up while you're fidding with shutter speeds), you'll need someone who's familiar with inspecting the firmware's code, to get this implemented.

Yes, appears read-only to me too... And it's true that the menu keystroke alternative isn't particularly inviting.

From what Aged says, one would guess that it takes 0,5 s for the IS system to be reliably up and running once enabled and that the functions that control the IS mode could be found not only from the Canon menu code, but also from panorama mode. That horizontal-only IS is available as a mode in a570is among others, even has it's own icon (which btw doesn't seem to be used during a570is panorama stitch mode when in the normal always-enabled IS mode).

Logged

ewavr

1057
A710IS

Re: Automatic IS Disable/Enable

« Reply #4 on: 13 / July / 2008, 08:48:48 »

Quote from: LjL on 13 / July / 2008, 07:33:14

... except I absolutely cannot find any function, in the currently published stubs (including DataGhost's), that would set the IS mode. PROPCASE_IS_MODE appears to be read-only, so unless you're willing to have this simulated by keystrokes (with the unpleasant result if seeing the menu flash up while you're fidding with shutter speeds), you'll need someone who's familiar with inspecting the firmware's code, to get this implemented.

In A710IS:

StopISDrive()
StartISDrive()
StartISPanDrive()

example of usage:
http://trac.assembla.com/a710/browser/platform/a710/sub/100a/capt_seq.c - from line 48.
IS turned off during shoot, if Tv>1sec

Logged