View Full Version : A beer for insight?

2011-Feb-02, 03:19 AM
Hello all.

Like most new posters, I'm looking for advice and have high-hopes. I'd prefer not to debate my approach or any thoughts on that end, just receive to-the-point advice on some options for what I'm trying to do. I'd like to come back for "thoughts" after I can take in and learn from you guys on which equipment you recommend.

I'd to receive your advice on two approaches:

Option A) Decent Budget

Option B) Advanced Budget

Let's leave these numbers nebulous for now... pardon the pun.

Goal: Great pictures of planets/moons in local system. Detailed pictures of deep-sky galaxies, clusters, etc. This is a higher priority to me. Given my namesake, I'd love to get quality pictures of the Orion/Horsehead Nubula.

Background info:

Photographing often, with ability to observe.

Portability is desired. I think I'd get more use out of something that's portable.

I live in an area with a good bit of light pollution. Obviously, I can travel 30 minutes and reach better areas. But that said, I don't live in a dark-sky hotspot.

Quality of the shot/optical quality is important. I don't want to invest a dollar in anything that might come out the least bit blurry.

I do have currently a Rebel XTi 10 megapixel.

I am planning a Canon T2i. I will have some very good lenses in the 200-400mm range for it.

I believe that I would prefer to have a computer-controlled device. I am not sure what this unlocks to me, but I'm very IT savvy and I'm sure this opens up new worlds of possibilities.




Is there any reason I should get another camera instead?

What do I need in terms of an Equatorial/Goto mount & telescope?

What attachments do I need for my Canon T2i?

What attachments do I need if I use my higher-end lenses, such as the 200-400mm Canon EF lens? Is this approach common, or would I just use the telescope?

Will I need to buy two telescopes/lenses if I want to do local system AND deep-sky objects?

I have looked into Goto systems and understand them as a quick way to calibrate on objects. Is there a better approach/preferred system?

Is there any chance I could get something on a plane? I have family in Portland and would love to travel there/St. Helens for some photographs.

I'd like to be able to take a few pictures a night. Can this be an automatic process via computer software?

What mount should I be considering? Telescope? All-in-one? Eyepiece? Other?

What other questions should I be asking?


Thanks all... very much looking forward to your thoughts. This is a hobby I've considered for quite a while!


2011-Feb-03, 12:29 AM
Background info:

Photographing often, with ability to observe.

From what I gather from answers from experts here on similar questions, it's really, really difficult to answer such questions. But I think they would at least like to know what you have photographed before. It's not clear if you've tried astrophotography before, or only "earthbound" objects.

2011-Feb-03, 07:47 AM
Detailed planetary imaging and Deep sky imaging are two very different goals requiring entirely different cameras. For planetary work you want large aperture for fast exposure times to freeze the seeing. You want a camera that can capture at least 900 images per minute! This means a video camera which of necessity for high speed has high noise. But software will sort through the many hundreds or better yet, thousands of images finding those that best resolve the planet. Though the planet or our moon is likely distorted in shape by the atmosphere much like stones seen at the bottom of a stream are distorted though clear. Point out various features you want the software to align on and it will not only find and stack the best images but will use those anchors to remove the distortion creating an image far clearer than you ever saw through the eyepiece. Once a few hundred are found and stacked they can be processed severely to bring out even more detail since, while any one image is quite noisy, the signal to noise ratio improves greatly when a hundred or more are stacked. One hundred would increase the SN ratio by a factor of 10 for instance. Since no Deep sky camera or DSLR can do this you need a good web cam such as the Flea 3 or a DMK camera for this process. Fortunately, as astro cameras go they are "cheap". Software is inexpensive to free as well. But you do need a large aperture scope (8" minimum 12 to 16 inches better, and it must be of very high optical quality. The mount is not very important. A rather poor one will suffice. A high quality Dob reflector on a Poncet platform for instance will work great.

Deep sky is a very different animal. Here the mount is paramount (a pun as one of the premium mounts is a Paramount). The higher quality the mount the more you will be able to do with deep sky imaging. Nearly any CCD camera or even DSLR can take great images if the mount is up to the task. Even the optical quality of the scope isn't much of an issue as seeing and mount quality will determine detail for the most part. But a refractor with chromatic problems is a pain to work with so if choosing a refractor it need be an ED or APO design. Also if using a large CCD most scopes have a curved FOV that will require a corrector. Premium scopes come with such correctors or they are available matched to the scope at added cost. Lesser scopes get by with generic correctors though finding the one best for a particular scope requires some research. Spacing of the corrector and CCD is usually critical. A few scopes don't need these. A few refractors such as the Tak FSQ line, the Celestron EdgeHD and Meade ACF scopes already have flat fields. The EdgeHD has a built in corrector that requires correct spacing. The ACF has a wider range that it works with but the correction isn't quite as good. The gold standard is the FSQ line.

For deep sky work you have to decide what you want to image. If you want wide field for imaging fantastic large nebula that requires one type of scope and CCD. Here field of view is king. For imaging distant galaxies, typical planetary nebula etc. you want a very different scope and possibly CCD. For the latter you also need to match these to your local seeing conditions so you don't over sample the image. Oversampling doesn't hurt in the sense the final image is still very good, but the imaging time to achieve it will be far longer than necessary so it is a time waster. Undersampling will cost resolution you were trying to achieve.

Some setups can try to do both but will end up being only fair at either though great for some middle ground objects. To do it all you will need two or three scopes and cameras or more. No one combination can do it all. Starizona has a lot of good basic information on their website. Basic books like Covington's Astrophotography for the Amateur gives more detail. You need to do a lot of research before proceeding.

Find a local club with imagers and get some hands on help is better yet. They can save you a lot of headaches and reinventing the wheel.

If you've done ordinary photography you'll find that is often a handicap as many things you learned there are turned on their heads in astro imaging.

I didn't address your individual questions as the answer to all right now is "Maybe" or "It Depends." Certainly not yes or no. Anything you suggest is possible, just that all involve compromises. Only you can decide which ones you can live with and which you can't. To do that you have a lot more learning ahead.

For deep sky work start simple which means short focal length scope with a average pixel size or larger CCD. This puts the least strain on the mount. Or even better just the camera and basic lens on the mount. Learning the needed skills to guide a high resolution deep sky setup is a very difficult task with many potholes along the way. You will need to learn highly accurate polar alignment, how to adjust guiding factors to your mounts quirks and many other things along the way.