Digital camera questions
Over the weekend I learned how to operate my digital camera in "live" mode, and it occurred to me that this would be a great way to achieve focus quickly. You focus in live mode, then switch to still mode after locking focus. My questions for the informed members of the list are: are all digital cameras capable of operating "live"? Is this a "standard" method for achieving focus? Also, it seems that my computer dumps about half the available frames. Is the save ratio set by the processor speed, available RAM, or the software? Any good instructional books recommended? My current model is a low-resolution cheapie (only $19 at Wall-Mart, including some nice image processing software), but it's proving very instructional. Live mode also captures thousands of images, which can later be culled-out of the file and stacked for a better image. Thanks C. __________________________________ Do you Yahoo!? Protect your identity with Yahoo! Mail AddressGuard http://antispam.yahoo.com/whatsnewfree
Chuck, As to half the frames getting dumped, while I'm not certain, my guess is that it probably has nothing to do with CPU speed or RAM or the capture software, but the method used to connect the camera to the PC. If you are going over a serial cable, the I/O speeds are quite slow and would easily explain the data loss. If over USB, a lot faster but could still prove enough of a bottleneck to drop frames. Firewire would be the ideal but not likely an option on a $19 camera! FWIW, Rich --- Chuck Hards <chuckhards@yahoo.com> wrote:
Also, it seems that my computer dumps about half the available frames. Is the save ratio set by the processor speed, available RAM, or the software?
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Thanks, Rich. It's not really a problem for astro-photography, the number of frames retained is still sufficient to achieve focus in real-time. Were I to make a regular movie or set up a Webcam, it would be a definite problem. I'm looking at *real* digital cameras & scanners now, hopefully will do some shopping soon. I'm amazed at the price drops I'm seeing now over a year ago....you can get 4 megapixels now for around $250! C. --- Richard Tenney <retenney@yahoo.com> wrote:
Chuck,
As to half the frames getting dumped, while I'm not certain, my guess is that it probably has nothing to do with CPU speed or RAM or the capture software, but the method used to connect the camera to the PC. If you are going over a serial cable, the I/O speeds are quite slow and would easily explain the data loss. If over USB, a lot faster but could still prove enough of a bottleneck to drop frames. Firewire would be the ideal but not likely an option on a $19 camera!
FWIW, Rich
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Chuck, the regular digital camera I borrowed was almost worthless for astrophotography. They're pretty grainy and I understand they're awful for long exposures -- I think signal noise builds up. That's why the real astrophotography digitals, like SBIG cameras, are relatively expensive. For a low-end camera that may do the trick, try a webcam. The types many amateur astronomers use work extremely well on bright targets like planets and the moon. You shoot a video then stack the best frames using freeware like RegiStax. According to the latest issue of one of the big mags -- I take S&T and Astronomy and don't remember which it was in -- some of these cameras can be modified to allow long exposures. Best wishes, Joe
Thanks Joe. I understand the limitations of these cameras; acutally for bright objects such as the moon, planets and sun, they are fine. For dim stuff, I'm still steeped in emulsion-based phototgraphy (for the time being). The grain problem is partly from not doing one's homework. You have to match pixel size to the resolution of the particular optical system you're using. Have you tried using it in "live" mode for focusing? C. --- Joe Bauman <bau@desnews.com> wrote:
Chuck, the regular digital camera I borrowed was almost worthless for astrophotography. They're pretty grainy and I understand they're awful for long exposures -- I think signal noise builds up. That's why the real astrophotography digitals, like SBIG cameras, are relatively expensive. For a low-end camera that may do the trick, try a webcam. The types many amateur astronomers use work extremely well on bright targets like planets and the moon. You shoot a video then stack the best frames using freeware like RegiStax. According to the latest issue of one of the big mags -- I take S&T and Astronomy and don't remember which it was in -- some of these cameras can be modified to allow long exposures. Best wishes, Joe
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Chuck, Make sure you visit the digital astro group on Yahoo -- there's a lot of folks doing some great photos with modest digital cameras (not just webcams). Debbie Whitaker has looked into this and can tell you more about it. Folks on that list can certainly recommend which brands work better than others, what the focusing issues/solutions are, etc. -Rich --- Chuck Hards <chuckhards@yahoo.com> wrote:
Thanks Joe.
I understand the limitations of these cameras; acutally for bright objects such as the moon, planets and sun, they are fine. For dim stuff, I'm still steeped in emulsion-based phototgraphy (for the time being). The grain problem is partly from not doing one's homework. You have to match pixel size to the resolution of the particular optical system you're using. Have you tried using it in "live" mode for focusing?
C.
--- Joe Bauman <bau@desnews.com> wrote:
Chuck, the regular digital camera I borrowed was almost worthless for astrophotography. They're pretty grainy and I understand they're awful for long exposures -- I think signal noise builds up. That's why the real astrophotography digitals, like SBIG cameras, are relatively expensive. For a low-end camera that may do the trick, try a webcam. The types many amateur astronomers use work extremely well on bright targets like planets and the moon. You shoot a video then stack the best frames using freeware like RegiStax. According to the latest issue of one of the big mags -- I take S&T and Astronomy and don't remember which it was in -- some of these cameras can be modified to allow long exposures. Best wishes, Joe
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Hi Chuck, I borrowed one of the paper's big digital cameras and made a set of Mars exposures that I thought would make everybody fall over in astonishment. With these cameras you can look through the eyepiece and focus just like a normal SLR. After I took them, the views on the tiny screen looked great. But when I saw them under normal lightning conditions, their many flaws showed up. I bought a webcam for less than $100, which isn't as good as the Phillips I keep hearing about, and it did a far better job. Thanks, Joe
participants (3)
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Chuck Hards -
Joe Bauman -
Richard Tenney