CHDK - Canon Hack Development Kit

[dmerger]

I have a Canon PowerShot A720is, which doesn't shoot RAW.  I'm considering trying CHDK, mostly out of curiosity.  I'd appreciate any advice before I try it.

[Graystar]

I use it with my A710 IS.  Probably the most interesting thing I’ve found is that it validates some of the limits placed on the camera by Canon.

CHDK big claim to fame is RAW capture (and now in DNG format as well.)  This is nice.  But it’s still an image from a tiny sensor that captures in 10-bits.  No matter how you cut it, it’s still limited to 6.5, 7 stops of DR at best. 

CHDK allows the aperture to be set to f/14 on an A710.  And when I did, I saw exactly why the aperture shouldn’t be set to f/14.  Diffraction effects were horrible.  Basically, going beyond f/8 doesn’t get you any more DOF.

CHDK allows most cameras to use optical zoom when shooting movies.  And when I did, I heard the reason for Canon limiting zoom to digital zoom only.  The sound of the zoom lens was horrendous.  CHDK now has a feature to cut sound recording when zooming.

Basically, if you’re looking to “unlock the potential” that your camera has for better images...sorry, that’s not going to happen.  It really is giving you the best it can.

That’s said, CHDK is fantastic for performing a variety of specialized tasks.  The intervalometer, motion detection, and other scripts are very useful when you need those functions.  Histogram junkies will get their fill with all the histogram options.  And there’s an amazing array of methods to control the camera’s operations that can’t be achieved any other way.  I made a USB based remote release that was invaluable when using my A710 for digiscoping.  Couldn’t have done it without CHDK.

The camera’s firmware is never changed, so CHDK is safe to use...It’s really just a piece of software that runs on the camera instead of on a computer.  So CHDK is great for what it does.  Just remember...it’s still a compact...CHDK will not turn your A720 in a Canon DSLR.

[dmerger]

Thanks for the info, Graystar.  Yes, my main curiosity was to try RAW with my camera.  As you rightly note, its DR is limited and I often get blown highlights, but my camera is just an inexpensive P&S, so I wasn't expecting more. I just use it for snapshots anyway.

The one thing about my camera that bugs me, however, is that the continuous shooting mode is not sticky. Every time I turn on the camera I have to manually enable that function. I'm not sure if CHDK would fix that problem, but may be worth a try.

Not much else about CHDK has a lot of appeal to me.  Some of it is cool, but I doubt that I'd use it.  I've only taken a couple of videos all the time I've owned that camera, but optical zoom when shooting video would be nice and may get me to shoot more video.  I'd need to check on the noise issue, of course.

Again, thanks for the info.

[NikoJorj]

I got one on my ixus850=SD800.

Shooting raw still allows a bit of leeway, mostly for complicated white balance problems, a bit for tonal rendition too (as said, don't hope for miracles in this area). The camera is frozen for a few seconds after a shot, making it clear that the CHDK can't change the innards of it.

The big other plus is the ability to customize the UI (live histogram, blinking highlights to solve your HL problems, and so on), even if the CHDK's UI itself is rather intricated (more menus and submenus than you can shake a joystick at).

Executive summary : a mixed bag experience, but you sure have to try it.