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Another first astro pic


rjc404

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Here's my first astro pic

Vega - first astro pic

It took me two hours of faffing about in the garden trying to figure out how to get my DSLR to focus when connected to my 150PL until I remembered to use the magnify button on live view... doh!

After all that effort managed to get a nice test shot of Vega and a rushed dodgy shot of M13 as the clouds rolled in.

This imaging thing could become a bit of a habit... oh dear!

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And another one. Managed to get out last night and thought I'd try and take the Dumbbell Nebula as it's a fairly bright target that's out of the way of light pollution. Just started imaging (4 x 60 sec) and someone started a fire down the road... at 12.00am! The smoke soon put paid to any more images (It was a beautifully clear night... aghhh!) Hopefully they'll be some more clear nights soon and I can get a bigger bank of images of a target. Anyway here's my effort for what it is worth:

Dumbbell2web

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Thanks for the feedback. If the smoke hadn't blown in I'd have definitely tried to get more light frames and dark frames to see what I could tease out. Not completely sure about flats yet and how I go about taking those.

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Thanks for the feedback. If the smoke hadn't blown in I'd have definitely tried to get more light frames and dark frames to see what I could tease out. Not completely sure about flats yet and how I go about taking those.

Flats are easily taken by pointing the telescope at a light panel or computer screen showing only a full screen white picture. Then set the exposre time so the image is about halfway saturated. Ie the histogram peaking between 1/3 and 2/3. You basicly want a grey image halfway between black and white. You also need to make sure the camera doesnt move or rotate in the optic train before you take flats, ie the whole rig needs to be exactly the same as with the lights.

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Can I just ask what is meant by this? Its it the same as bracketing?

Darks are shots taken with the telescope cap on then subtracted during processing to remove internal camera noise, amp-glow and bleeding from the final image. Flats are taken by pointing the telescope towards a light panel or bright evenly illuminated screen and then setting the exposure to make a grey image (between 1/3 and 2/3 saturation or the sensor). This is to isolate defects in the optical train like dust and vignetting, then subtracted during processing to make a cleaner image. If you're curious to know more about basic AP-techniques check out Steve Richard's book "Making Every Photon Count", it really helped me a lot.

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  • 2 weeks later...

Added a few more to my gallery now after a couple of clear breaks in the sky over the last week. Still learning to use all my equipment (which I imagine I will be for quite some time to get the best out of it) but hopefully slowly getting better.

Here's my second attempt at M81 on a slightly windy night. ISO 800, about 35 images in a range from 30s, 45s, 1min, 1min 30 and 2mins and processed with the same number of darks and about 20 flats and bias.

Turns out two minutes gave the best histogram but I forgot to check that after each image until about half way through the session... doh!

Going to keep trying to use M81 as a reference point while I figure things out. Might try ISO 1600 next time and see if it will give more signal or more noise. I know my set up isn't made for imaging but I'm happy with the small steps taken so far.

post-31280-0-96059000-1379020769_thumb.j

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Here's my latest iterative attempt at M81 and M82 whilst learning to use my kit. 26 x 2 minutes exposures plus 20 x darks/bias/flats.

ISO 1600 seems to have brought out a slightly better image at the same sort of exposure length as I was trying with ISO 800. I think this could have had more detail but the moon was up for half the imaging session.

Really enjoying learning to use all this. I'll have one more go at this target and change one of the settings again to see if it makes any difference.

M81 And M82 mark 3 ISO 1600 (web)

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Thanks for the positive feedback and comments. I think I'll have to leave my next practice session until the moon has dimmed a bit though. 

Out of interest, when does the moon stop interfering too much with astrophotography of DSOs or Planets? Obviously now it is full, it creates quite a sky glow. After new moon, when does the moon start interfering with photography again?

I don't mind too much as still plenty of stars to look at visually.

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Thought I'd might as well do something whilst the moon was up. Here's a single exposure I took through my Canon EOS 700d and Skywatcher 150PL. Also practised taking some uncompressed video at 640x480 with EOS Camera Movie Record and stacking in Registax but the single exposure using RAW was better.

post-31280-0-99735600-1379850573_thumb.j

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Looks like you're a natural at this! Excellent images for someone with some experience in astrophotography let alone someone just starting out.

Also practised taking some uncompressed video at 640x480 with EOS Camera Movie Record and stacking in Registax but the single exposure using RAW was better.

You will find that the compression done in-camera to keep up with the high frame rate causes the file to loose data. If you want to go down the video route and stack the individual frames then you could start with a web cam - but keep the frame rate down to say 10 fps (frames per second). To get higher frame rates without compression then you need to start looking at dedicated planetary cameras at about £80-£90, or CCD/CMOS astro cameras for upwards of £250.

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