Hi all. (My apologies if this is the wrong place)

My names Mike and I’m very new to astrophotography. I had an 8in Dopsonian(I think that’s the right name) as a kid but otherwise have little experience with telescopes and even less with photographing what I saw, but I’ve always been obsessed with the night sky. So I’ve just dropped a small fortune on a good (I think) starter rig, based around a Celestron C8, which should be here next week. My biggest interests are how to get the bright vibrant colors in nebulae and galaxies. I’ve been reading a bunch of the posts here and on the web in general to get an idea of what to do but I think I’m at the threshold of what I can figure out on my own. If I understand everything I’ve read (and that’s a stretch), then the two biggest things ill need are filters and software. I got a freeware program (“iris” or something) but couldn’t figure out how to use it with my DSLR, maybe ill have better luck with the CCD when it gets here. Any help, direction, or ideas are greatly appreciated Thanks and clear sky’s.

Hi Mike,

"CCD Astronomy" by Ron Wodaski is a good starting place to get a basic understanding of the ins and outs of astrophotography. (You should be able to google the title and order from his site) There are other good books as well, but I have found this one very thorough. There is a steep learning curve, but if you are persistant, it can be a very satisfying pastime.

Good luck!

Kent

Start very simple, you are trying to climb a 5 mile near vertical mountain without experience. The folks taking those great photos have years of observing experience followed by years of astrophoto experience. It isn't as easy as the manufacturers want you to believe!

First pick up a copy of Covington's Astrophotography for the amateur. It will answer many of your questions. Wodaski's book is also highly recommended but I'm in the minority here in that I found it mostly to be a manual for CCDSoft and Maxim DL (he wrote both manuals and pulled about 75% of the book word for word from them). So if you use some other control program much of Wodaski's book isn't all that useful as he often uses menus from each in the how to parts of the book. It doesn't cover DSLR or planetary work with a web cam which are better staring points. Covington's book does but in less depth for CCD's. But it covers many of the basics Wodaski's book assumes you already know but you likely don't. To me it is better for the rank beginner. Then move to a more advanced book.

Next work on getting usable images from the DSLR mounted piggyback atop the C8. See the current issue of Sky and Telescope for a good article by Jerry Lodriguss. Covington has a good book on DSLR photography but it assumes you have already read the first book.

When you can get good shots using the DSLR and say a 400mm lens you will then be ready to move up to imaging deep sky through the C8. Still it is a big jump from 400mm to 2000mm. Things will get far more demanding. Just focusing is a problem. The focuser has to be ultra precise. Using an f/4 lens for instance you need to hit focus within 34 microns or about one thousandth of an inch.

For starters through the scope work on bright things like the moon and planets. For this a USB 2 webcam is the best choice with free Registax to sort through several thousand AVI frames, stack and process them.

You don't say what CCD you've ordered. Is it OSC or mono? Is it ABG or not? Did you match the pixel size to your focal length and seeing. Unless the CCD is small you'll need a compressor/flattener as a SCT has a very curved field of view so only part of the image on a medium size or larger chip will be in focus. Keep in mind a chip size of about 20mm diagonal is about as large as such a typical flattener/compressor can handle so buying larger is a waste of money with that scope. With the flattener and a matched CCD you can get great results but make sure the distance between the flattener and camera is correct. Otherwise it can really add more problems than it cures.

When ready for deep sky work taking many short one minute or maybe less exposures is the way to start. The results aren't great but are impressive to a beginner. I'd have killed for such results when using film in the 50's and 60's for instance. But read noise puts a limit to how many of these you can stack, after 50 or so you've reached a point of little gain. Once you get guiding (you'll need an off axis guider or a SBIG camera with internal guider chip) down you can increase the sub exposure time to 5 minutes or more and greatly decrease noise and increase image quality. You will be learning how to subtract darks, apply flats and normalize images along the way. Taking good flats can be an art in and of itself, especially without a good lightbox.

For now use the C8 for viewing while you do a lot of reading up and gain experience just using the scope, polar aligning it and learning your way around the sky. You really have to know the sky well to put a DSO onto a CCD chip. They have a far smaller field of view than your low power eyepiece and even a Celestron Goto mount will often miss the chip entirely so you have to know the area well enough to know what direction and how far to move the scope to find it. With something big and bright like the moon, no problem, with M57 it's a very different story!

For image processing there are lots of programs, IRIS, I too found hard to fathom. It was written in french and loses a lot in translation. I have a french speeking friend who said the french manual was far superior and cleared the fog making it usable. My high school french left me 5 decades ago! Personally I use CCDSoft to acquire, calibrate and normalize the images. Most of that is done as the sub frames are taken. When alignment is necessary I usually use Registar as it compensates for errors others don't. A SCT is very temperature sensitive so you have to refocus constantly. That can change the image scale a wee bit. Enough to color fringe stars. Other cheaper alternatives are available, just not as versatile. I use Photoshop with the FITS Liberator plugin for the image processing itself though I have added many plugins to it, some free some have a nominal fee such as the gradient removal one. Only CS and above is really good for this as it has far better 16 bit support than does earlier versions. Some do a lot of their processing in other programs like CCDStack and Pix Insight but most use Photoshop for some steps. Beginners can make far cheaper Elements and free Gimp work but they don't have all the tools or 16 bit support found in PS. I don't know if FITS Liberator works with GIMP. Probably does but I can't verify that. You need it or some other way to get FITS files into image processing programs that don't support FITS. IRIS does as do Pix Insight and CCD Stack as well as others. It's those not designed from the beginning for CCD work that lack FITS capabilities.

Anyway, you have a long steep road ahead so start slow and work up to the more complex stuff.

Rick

There is a good explanation of how to use IRIS here.

http://www.saratogaskies.com/article...ook/index.html

__________________
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Wow, thanks. It seems my thread name was more appropriate than I thought. The camera I ordered is the "SSDS Monochrome Imager II". I’m also getting a good web cam and adapter for planetary shooting. I didn't get it before because I thought it was a jerry rigged sort of thing, but it seems to be a very recognized method. I tried to get Registar but it wont run for some reason. what program would you recommend for my DSLR? i figure i can play around with some simple shots to get the feel for processing.

Did you match the pixel size to your focal length and seeing?
what does this mean? I’m afraid I’m still too new to decipher it.

For correct sampling of a deep sky image the pixel size should be one half to one third the size of a typical star's disk enlarged by seeing. For most parts of the country this will be about 2 to 3 seconds of arc. So if your seeing is say 3" of arc you want a pixel size no smaller than 1 second or larger than 1.5 seconds for best sampling and ability to get the full resolution your skies allow. This is for deep sky imaging. It doesn't apply to planetary work. There a typical web cam running at f/25 to f/30 is what you want. Oversampling images (pixel too small) just increases exposure time without any gain in image quality so is to be avoided if at all possible. Undersampling (too big of a pixel) can result in odd looking stars (square). But it does reduce exposure time and is often done intentionally for wide field photography. There are ways to deal with the star shape as well so this isn't necessarily bad. But you do give up resolution to get this reduced exposure time and wider FOV. There's no free lunch here either.

The formula is:
Sampling in arcseconds = (206.265 / (focal length in mm) )* (pixel size in microns)

Your camera has non square pixels so the images will have to be resized to square them up or the image will be distorted. Orion's software may do this automatically, I don't know. For the formula use the larger dimension 8.6 microns. With a f/6.3 reducer/flattener you'd have a 1260mm focal length. That would result in about a 1.4" pixel scale for a bit over 17 minutes FOV on the long axis. Short one would be about 13 minutes. Pretty small but good for planetary nebula and many galaxies. Without the flattener/reducer it would be about 11'x8'. Smaller than I'd want to work with. Just finding the object would be a pain beyond reason and very limiting. In any case the pixel scale is reasonable. Field of view a bit limiting however. You might want to look into an even stronger reducer but they can be really touchy as to mounting distance between camera and reducer that if not correct can create problems you don't need.

Wodaski has calculator on the net you can download at:
http://www.newastro.com/book_new/camera_app.php

I'm not sure how it handles non square pixels.

You mention Registar. That is very different than Registax. Though I've not heard of a problem running either. You may have a faulty download. Registar is for aligning CCD images for stacking or mosaics and has nothing to do with web cams nor is it close to free though you can download a version that can't save images for free. Registax is probably the best planetary web cam processing program. I've not heard of any issues running it under Vista but haven't tried it. It works fine under W2K and XP my two operating systems. K3CCDtools is another but it is pay for the best version. I have heard of that not running under Vista yet others had no problem.

Rick