How can I improve my astrophotography?

I currently own an 8" Orion SkyQuest Dobsonian reflector. It has a focal length of 1200mm, and with it I have a 25mm Plossl and an 8mm Hyperion eyepiece. I also own a 2x barlow lens. The following image was taken with the 8mm eyepiece and 2x barlow (300x mag).

http://a6.sphotos.ak.fbcdn.net/hphotos-ak-ash4/310...

It was made from a ~20 second video of Jupiter using a Nikon Coolpix S3000 digital camera. The framerate of the camera is 30fps. The video of Jupiter was processed using Registax.

I'd like to state a few things. Since my telescope has a dobsonian mount and isn't motorized I have to improvise when taking pictures. What I do is once I get an image on the scope, I place my camera up to the eyepiece of the lens and start recording, and track the image as it moves along the field of view with my camera. Then I take the image and process it on registax. I am curious as to why my image doesn't look anything near as good quality as the following, taken with a 6" telescope.

http://www.youtube.com/watch?v=F84m6ETJyOU

Youtube thumbnail

&feature=related

Should I change the settings on my camera? Longer exposure? I'm open for tips and suggestions.

3 Answers

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  • Mark H
    Lv 5
    8 years ago
    Favorite Answer

    I think you're pushing the limit for what can be done with the equipment you're using. An extra nice night, or some random luck might get you a better result, but you're doing quite well.

    The first thing I'd change is the way your camera is set up.

    Option one is a mechanical coupler along the lines of an eyepiece projection holder and an adapter ring to to mechanically couple the camera to your eyepiece. In the short term, this is probably the simplest/lowest cost upgrade that will get you some improvement with what you're using now. But you'll outgrow it quickly.

    Option 2 is a dedicated planet camera. These are similar to web cameras, except the telescope becomes the lens. You'd use it instead of an eyepiece. and you'll need to bring a netbook or laptop to run the camera. The Celestron Neximage is a budget one. I use ones made by the imaging source. The main difference between them besides cost is build quality.

    Either of the above options can be used with a barlow if you need it for image scale.

    Here's a shot of Jupiter and Io a friend and I took with an imaging source camera using an Astro Physics 140edf:

    < http://www.holden-insurance.com/jupiter8109I.bmp >

    Here's a shot of the Moon we did with the same setup - it's a mosaic of several shots stitched together.

    < http://www.holden-insurance.com/Moon140M.jpg >

    If you want to shoot deep sky shots, you'll also want to look at changing to an equatorial tracking mount, as field rotation will start to become an issue with exposures more than a few seconds.

    Source(s): Over 30 years in the hobby.
  • There are lots of variables, including seeing conditions and collimation. I think your shot of Jupiter is pretty good under the circumstances (no drive). The video of the 6 inch telescope's view would suggest that the telescope is on a driven mount. That means that since the image is centered throughout the video, MORE images can be sampled for stacking. That is probably the main reason that the stacked image was sharper and more detailed.

    So you might want to either invest in an expensive heavy-duty equatorial mount, OR buy or build and equatorial platform that the whole Dobsonian set up can be placed upon if you want the maximum potential from video imaging.

    In any case, or in the meantime, by all means experiment with settings on both the camera (though again I think your results are pretty good) or in the Registax program itself.

    --------------------------------------------------------------------------------------------

    Added: Here are some video images I took a few years back in a driven 8" SCT. I used a Phillips webcam.

    http://i17.photobucket.com/albums/b83/urban-astron...

    This was prior to wavelet processing in Registax. Note the lack of detail.

    http://i17.photobucket.com/albums/b83/urban-astron...

    The same shot stacked and processed after tweaking the wavelet settings appropriately. WAY more detail now. A few years back one of the equatorial belts were almost completely absent, hence the unusual look.

    http://i17.photobucket.com/albums/b83/urban-astron...

    Another stacked image with the Great Red Spot this time, though overall not as sharp.

  • 8 years ago

    Well, ..., first off, IMHO, that's a great shot you should be proud of it! Second, IMHO, your picture is a lot better than the one in the video. The other video is just using an eyepiece with a field of view that is more narrow than your Plossl.

    Also, you should try the following:

    1) Get a T-riing adapter for your camera along with a diagonal that has a flip mirror in it. In this way you can fix your camera to the scope without loosing the ability to hand guide the scope during exposures.

    2) Try taking a lot of short exposure frames (e.g. 300) rather than one long video and stacking those.

    3) Make sure you take a Black Frame and a flat frame as reference frames.

    4) Try using prime focus (Camera mounted directly to the scope) rather than shooting through the Plossl.

    5) Pickup a copy of Robert Reeve's "Astrophotography for DSLR's" or "Astrophotography for web cams"

    6) Joining your local astronomy club can also give you a set of folks to bounce your ideas off of.

    Good Luck you're already off to a great start!

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