Please help me with the CHDK menu for my Canon SD800?
June 19, 2008 6:28 PM   Subscribe

CHDK question for Canon SD800 IS

I installed Allbest's CDHK on my Canon SD800 IS. I want to do one thing: shoot photos with a several-second exposure (mainly to get the blurred effect of moving water, etc.). When I do this, using the instructions in the Wiki, the picture comes out completely white or almost completely white. I'm sure that there is a way to set it correctly. But, after looking through the Wiki again, I can't figure it out. MeFites, you usually know all. Can you help me?

In case you want to know what version of CDHK I'm using, it's allbest-ixus850_sd800-100e-50.

Thanks, all!
posted by laskagirl to Computers & Internet (13 answers total) 3 users marked this as a favorite
Response by poster: Whoops. CHDK. Thanks!
posted by laskagirl at 6:29 PM on June 19, 2008

I own the SD800 IS (also using CHDK), and whenever I want to set the exposure, I just go into manual, go to exposure, hit the menu button to go into "night mode" and set the time there. I just tested this with a 6 second exposure in a moderately bright room, and while the image turned out brighter than normal, you could still see all of the detail. Is this the process you use?
posted by niles at 6:54 PM on June 19, 2008

It may be that you've set up the long exposure correctly, but it's causing your photos to become overexposed. Try turning the ISO setting all the way down and the aperture all the way up. Those settings are limited by the physical construction of the camera; for example, ISO 50 and f/8.0 is as low as my PowerShot A610 can go.

P.S. Are you sure you even need CHDK? Most of the Canon point-and-shoot cameras seem to be able to go as high as 15 seconds with the stock firmware.
posted by teraflop at 6:55 PM on June 19, 2008

If it's still too bright even after you make the aperture as small as possible and set the ISO to its lowest value, you can get a neutral density (ND) filter to further cut the amount of light entering the camera.
posted by kindall at 7:08 PM on June 19, 2008

Response by poster: I used Niles' method and the image was still completely overexposed (using six seconds as a test). Dialing down the exposure manually didn't help. Night mode on, night mode off, no difference. I was using the lowest available ISO, which is 80. Is my camera broken?
posted by laskagirl at 7:29 PM on June 19, 2008

You're just capturing too much light. Keep dialing down the shutter time until you get a reasonable image. (You haven't said, but I'm assuming you're already using a small aperture setting.)
posted by knave at 7:32 PM on June 19, 2008

Response by poster: With this camera I don't think I can adjust aperture without CHDK, can I? So how are you getting a clear image, Niles?
posted by laskagirl at 7:45 PM on June 19, 2008

Best answer: Frankly, I'm not sure. I've never really had an exposure problem with my camera, which I'm assuming still sets the aperture in "manual" night mode. While I have CHDK, I didn't even know I could set the aperture with it (can you? I can't find the setting).
For what it's worth, I'm doing this in a medium sized room with three lights spread around the walls...I'd call it well-lit, but I wonder if whatever you're shooting is just plain too bright, which is entirely possible.
posted by niles at 8:11 PM on June 19, 2008

Response by poster: Niles, I think you're right. As you might be able to tell from my handle, I live in Alaska, where it is really, REALLY bright during the summer. And after I tried it in a room with shades drawn over a window, it worked. I guess the camera, which I do like in general, isn't made to do this in my conditions. I need to get one that allows me to manually adjust the aperture to use longer exposure in broad daylight. Alas. But all these comments were immensely helpful. Thank you! You guys are the best.
posted by laskagirl at 9:43 PM on June 19, 2008

I think the SD cameras only have two aperture settings. Any other variation comes from variation due to focal length.

I don't think there are any digital cameras that would let you stop things down enough to do a long exposure in full daylight. What you want is a neutral-density filter, though I'm not sure you'll be able to attach it very well on your camera.
posted by Good Brain at 11:20 PM on June 19, 2008

I guess the camera, which I do like in general, isn't made to do this in my conditions.

If you're using a tripod, could you take 100 photos exposed for as long as your camera can, and blur them together in Photoshop later?
posted by Mike1024 at 12:17 AM on June 20, 2008

I think the SD cameras only have two aperture settings. Any other variation comes from variation due to focal length.

I have disassembled an sd630 and sd800, this is true. There are only two "apertures". (I think they're just neutral density filters).

But there are a lot of ways to achieve long exposure effects. Mike1024 has a good one. Another thing you can use is neutral density filter of your own -- like this or this -- just set it in front of the lens. (You might have to build a little cardboard cone to keep stray light out).
posted by fake at 5:03 AM on June 20, 2008

Switch to Manual Mode

Go to the Exposure settings (the +/- 0 on the left)

Push Disp

Set the long shutter to the length you want (up to 15 seconds)
posted by JDHarper at 8:09 PM on June 21, 2008

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