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Member since: Sat Mar 29, 2008, 09:11 PM
Number of posts: 45,851

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Astrophotography on a budget: Sony NEX C3

I got my used NEX C3 a couple of days ago from Adorama, under $130 including shipping for the camera, 18-55 kit lens, attachable flash, battery, charger and original box/packing. The camera isn't pristine but it's in decent shape, mostly the LCD screen is somewhat the worse for wear, scratched some and the black surround on the clear plastic is looking rather rough.

So I tried it out last night with the kit lens set at 35mm and f4.5 (wide open at that focal length), the lens isn't particularly good for astrophotography but I didn't expect it to be, the camera on the other hand is brilliant for this purpose. There is a self timer setting that gives you a ten second delay and then takes five images in a row at whatever time exposure you set, in my case I used 30 seconds which is the max the camera will do on its own so I was getting 5 x 30 seconds for two and a half minutes per shutter button press. I tried different ISO settings and eventually settled on 800 as being optimum for my sky conditions f# and exposure length, if I was under darker skies I would go with 1600 probably though. I had the camera mounted on my small equatorial tracking mount so it followed the stars for no trailing, without the mount I could probably have gone for 10 second exposures while keeping the trailing to a minimum, 1600 ISO would work for that too. Long exposure noise reduction was turned off and I didn't take any dark or flat frames which would have improved the final image some. I just wanted to see how it would work without a lot of rigmarole..

Anyhow, here is the result of 55 x 30 second exposures @ ISO 800 registered and stacked in the freeware Deep Sky Stacker and then further processed in Iris (to remove the light pollution gradient) and Paint Shop Pro (curves, cropping and so forth)... Both the Orion nebula and the Running Man nebula right above it show up nicely and you can even see the Flame nebula just to the left of the leftmost star in Orion's belt. When I get an adapter for some of my prime lenses that are a lot sharper than the kit lens this camera is going to do very well indeed, the flange distance on the NEX is so short practically any lens in the history of photography can be adapted to it and there are adapters available for a lot of lenses now, you have to use them in manual mode but that's not an issue for this sort of photography.

The Comet and the Cluster, Lovejoy and the Pleiades (Updated with new images)

Nine exposures of 30 seconds @ ISO1600 Canon 350D w/Nikon 50mm f1.8 @ f4. Processed in Deep Sky Stacker, Iris and Paint Shop Pro. It was just above freezing so I could push the ISO and still get relatively clean shots out of my antique DSLR. I had about a dozen two second focusing and framing shots @ f1.8 and then I stopped it down to f4 and shot the thirty second ones before the sensor warmed up too much and got noisy.

You can just see a hint of the comet tail coming down like a rocket below it and the blue nebulosity in the Pleiades. It was easier to see in the bitmap, it's a bit too subtle for the jpeg. This is about the closest Lovejoy will get to the cluster it was just chance I had a clear night and a hole through the trees that lined up with the shot. Around here it's trees or lights, take your choice.

It's taken me a couple of years to learn how to get the light pollution gradients out of my shots, I was pleased with the way this one turned out it had a horrible red gradient across it with such a wide field.

So I got some more shots last night 1-17-05 and came up with these two images. Same setup as before but this time it was 18 images of 30 sec @ f2.8 and ISO 800.

The first image is the finished picture..

The second image is a negative that's actually the mask I used in one step of the processing to remove the light pollution from the finished image, it shows the extent of Lovejoy's tail which I can't get to show up in the final image if I get the colors remotely right, there is just too much light pollution for it to work with the equipment I have. the big blotch at lower right is the result of light pollution gradient across the image..

Andromeda slipping into the trees

The moon was far too bright last night for any serious deep sky imaging so I was tweaking my polar alignment setup routine and got a series of 34 images of the constellation Andromeda and the galaxy named after it as they slipped into the trees. Canon 350D with a Nikon 50mm f1.8 @ f3.2 30 seconds per exposure @ ISO800. Resized and processed into an animated GIF with VirtualDub. My tracking mount is an Ioptron Cube Pro used in equatorial mode.

The galaxy is near the center of the image and you can see a satellite sail through the frame about 3/4 of the way through the cycle.. Also note the color of the light on the tree to the right, that's from Christmas lights on the front of the house. Thanks to the moonlight and the local light pollution there were only a few stars that could be seen with the naked eye in the field, the only way I could tell the galaxy was even there was by looking at the images as they downloaded to my laptop.

Next time it's clear with moonlight like it was last night I'm going to try and get Orion rising through the bare deciduous trees we have on the east side of the property, that constellation is a lot more obvious and colorful than Andromeda, the galaxy is really the only standout thing about it.
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