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Imaging Saturn with a DSLR


A320Flyer
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Here's an example of saturn, 5/13/2011, captured with a Canon T2i and eos_movrec, using a 8" newtonian and eyepiece projection.

Doug, your image appears to be of a quality similar to that of an astronomical webcam. The only difference I see is that the colors are brighter using the webcam. Is there a way to better control the color with the T2i software?

Did you use the 7x zoom magnification in live view?

Thanks,

Peter

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Doug, your image appears to be of a quality similar to that of an astronomical webcam. The only difference I see is that the colors are brighter using the webcam. Is there a way to better control the color with the T2i software?

Did you use the 7x zoom magnification in live view?

Thanks,

Peter

I used 5x zoom, which is a feature in eos_movrec. Basically this mode gives you a section of the CCD that is "5x" or 1024x680 for T2i. I'd say the quality is about the same as crop mode video, but with the advantage that eos_movrec works with any Canon camera with liveview, and it's far easier to frame the planet. You can view the full frame, center the planet or move the 5x box, then zoom into 5x for the video capture.

With liveview it seems that you can set the ISO lower than what's possible with crop mode video. For Saturn I would use ISO3200 for crop mode, but with liveview I can use just about any ISO. My example was ISO1600. I haven't played with the software enough to understand how it's possible to use lower ISO, but using a lower ISO means a slower shutter. Perhaps a slow shutter would lead to other issues? Even with low ISO the liveview image has noise. I think the liveview ISO might be simulated somehow, and perhaps the shutter speed too.

Color is poor because of the high ISO. Perhaps if I stacked more frames it would improve. The example was about ~couple thousand frames at 30 fps.

The low brightness is probably just the shutter I selected. I find it hard to select a good shutter speed when looking at a bright screen in the dark outdoors. The imaged looked correct at the time, but my eyes were adjusted for darkness. You can always brighten the picture in post processing (a little).

Doug

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Doug/Pete,

I started this thread and have been keeping tabs on it even though it has gone a bit beyond me.

One question. I did notice eos_movrec mentioned in another post a few weeks ago. One of the responses poo-poo-ed the software saying that the chip on a DSLR was not designed to run continuously and that you run the risk of frying your chip if you use it. Have you come across any problems using it? Have you noticed any warm areas on your images? (sorry - two questions).

I have recieved my morgans webcam and tried it. I was a little dissapointed at the smallness of saturn on the image. I have ordered a eyepiece projection adapter to see if I can get saturn a bit bigger.

Bill

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One of the responses poo-poo-ed the software saying that the chip on a DSLR was not designed to run continuously and that you run the risk of frying your chip if you use it. Have you come across any problems using it? Have you noticed any warm areas on your images? (sorry - two questions).

It seems to me that the heat would be the same as using liveview, which I also do all the time. I use liveview for 10-15 minutes straight when aligning/calibrating the eq mount. It hasn't hurt my camera. I'm sure the sensor gets warmer, but how would this be different from using the video mode of the camera? I don't see any signs of "warm areas" in the liveview output when viewing a planet. When I stretch DSOs (normal shots) I sometimes see a cooler row of pixels near the sensor edge, but this is with extreme stretching of the image.

Regarding eyepiece projection: The Celestron 8-24mm zoom ep has T-threads on it. This is what I use.

Doug

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Ah! My DSLR is the Canon 1000d. It doesn't do movies. Maybe it wouldn't be a good idea for me to use the eos_movrec software.
Bill, I use a program called ReplayVideoCapture to record a movie of what LiveView is displaying, here is the link:

Replay Video Capture - Record ANY Video Playing on your PC

It seems to work fairly well; with it you don't need a camera that records movies, just place the capture frame of ReplayVideoCapture around the LiveView window and hit "record". The reason my image was fuzzy is that I used the focuser knob on my SCT which is a very inaccuarte way of achieving focus. I just bought an electric Crayford focuser that should improve the focus considerably.

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