need help for a setup for astrophotography

[aston martin]

hello everyone i am new to astronomy i have a celestron nexstar 8se (the single fork orange one) an i want to set up a rig with digital slr camera cause ccd is way out of my price range an first off i live on small island with no astronomy clubs or stores besides food store an liqour store hahah i dont understand why i need a autoguider scope for wen the scope tracks object already id also like it if someone could help by maybe giving me a setup for this 8se to make photos such as wat guide scope an if i need a different diagonal then a standard one etc hope to hear from one of u experienced smart astronomers this would be greatly appreciated oh yeah the small no store island has a good side no street lights or light polution ok thanks an happy alien hunting aston-martin

[Sticks]

I have moved this to Astronomical Observing, Equipment and Accessories which is the more appropriate location

[RickJ]

My first advice is to spend a year learning the sky and what's what up there since you say you are a beginner. Only then are you in a position to think about photographing it.

In the meantime I'd advise you to get a good book on the subject. It will answer your questions far better than we can in such short space. Covington's Astrophotography for the Amateur is a good place to start.

Don't use a guide scope with a moving mirror scope unless you can lock the mirror and focus with an external focuser. The mirror moves as the scope tracks and a guide scope can't see this movement so will happily track where the object no longer is in the main scope. Some frames will be useable but some will be lost because of this "mirror flop".

Use an off axis guider on the scope instead. Then both the camera and guider see the same movement of the mirror and you have far more usable frames.

Guiding is needed because neither you nor the mount is perfect. Now if the gears were machined to a millionth of an inch accuracy, bearings centered the same accuracy, shafts round to this degree, and metal didn't flex under load then you'd still have the problem of aligning the polar axis within a tiny fraction of a degree of the pole keeping in mind that atmospheric refraction constantly moves the position of the pole around slightly. Not knowing your declination it could be many seconds of arc. Can you predict this ahead of time and adjust for it? Of course not. Since we can't make perfect mounts and we can't align them perfectly then guiding becomes necessary. Also as an object gets lower in the sky atmospheric refraction raises its position in the sky so the tracking rate has to change to adjust for this or again you are off target no matter how perfect everything else is. Guiders handle this with ease but your mount is clueless to this problem.

In fact learning to train a guider to work at f/6.3 with your scope (you will need a compressor/flattener for that scope and camera) will be a challenge. Next Star's mount can be a bit quirky sometimes. Also you want a wedge. Do you have one. Alt azimuth is fine for visual work and planetary photography (use a web cam not a DSLR for that) it will cause rotation of the field when used for long duration deep sky photography unless you stack many dozen short 1 minute exposures after first aligning them to remove this rotation. Mounted equatorially this problem goes away unless it is poorly aligned on the pole. You will need to learn this art as well. At first it will be quite time consuming, but after you get the hang of it you can do it in 30 minutes with sufficient accuracy for 20 minute guided exposures. Permanent mounting pays big dividends here if that is possible.

For now I'd start with planetary photography with a web cam and Registax software (free). Also a DSLR mounted atop the NextStar on a wedge will take great wide field shots of the sky that will amaze you at the detail seen. Neither of these require highly accurate polar alignment or a guider. Keep the focal length of the lens on the DSLR for piggyback photography at 50mm (actual not equivalent) or less and you should be able to go 10 minutes without guiding with only an approximate polar alignment (say a degree or two of error). Since planetary photography uses very short exposures polar alignment isn't an issue at all thus making it a good starting point. In fact some error can actually increase the quality of the final image.

Without a wedge you can take shots through the scope in some areas of the sky by limiting exposure time to 1 minute or maybe less depending on where you are pointed and stacking dozens of shots. That too doesn't require polar alignment as you are set up alt azimuth. Just a good setup of the pointing computer routine is needed. This doesn't result in great photos but is a starting point. Stacking several dozen 1 minute shots to equal 2 20 minute ones adds lots of noise to the image but does give results most beginners find acceptable but most soon want more. Only a few objects react well to this approach but at least they are the ones most beginners think of.

Not having access to a club is a big handicap. Get the book I listed and after you understand it then get the one he wrote for just DSLR work. It assumes you know the first book well so don't get it until you are well acquainted with the first one. Note if you plan on imaging emission nebula with mostly H-alpha emission (the pink you see in most nebula) you will want a modified DSLR as the IR filter in stock DSLR camera's blocks most H-alpha light. You can get replacement filters that don't block H-alpha. This voids the warranty in most cases unless you buy an already modified one from a dealer. Not being a DSLR users I'm not all that familiar with the process. Hutech is one such dealer. There may be others, I just don't know. http://www.sciencecenter.net/hutech/canon/index.htm
Cloudy nights website has a forum just for DSLR users. You might want to lurk there.

While I mention problems with the NextStar (moving mirror, highly curved field and long focal length requiring a flattener/compressor and sometimes quirky mount) it is a far better scope for this than the one I started with in the 50's and I too didn't have a club to draw upon -- so I helped form one. It was the blind leading the blind but we did make progress -- snail paced at first but we go there.

You are just starting down that road but with far more assets available to you, even in your remote location, than we had. Your dark skies are an advantage, especially visually. The road is difficult and the learning curve steep. You'll make amazing progress in a year or two but getting there can be "interesting" at times. It certainly was for me.

Rick

[aston martin]

hello rick as i see u have quite the long time experience ill get the book over the net or a friend in a city can mail it to me it seems it is quite difficult not just point an shoot like pictures fishing an stuff i have been learnin the sky i found saturn on my own without goto or anything an that was awesome one more question for now is something wrong with my telescope it seems that focusing doesnt come in good its kinda blurry on things like vega an andromeda?this is a ok telescope to begin with right? thank you for your help sir aston-martin

[RickJ]

You don't give me enough information. What power are you using? How high were these? Both would be pretty low right now. Anything low in the sky will be fuzzy same as the setting sun or rising moon looks distorted. Seeing will vary from night to night and even minute to minute. So even high in the sky an object can go from sharp to fuzzy very quickly. Always start with your lowest power and work up to what the atmosphere is giving you that night.

You'll want a good star atlas (Tiron would be a good starter) and red LED flashlight as well as binoculars.

Astrophotography is not easy. Basic planetary shots of the moon with a web cam and piggy back (if mounted on a wedge and reasonably polar aligned) wide field photography with a DSLR are the starting points. Long exposure through the scope is far harder than the manufacturers want you to believe. Work up to it and you'll be fine.

Rick

[aston martin]

thanks for your help im just gonna keep looking at the skies an read more books for now an im gonna have to get lookin for dew stuff cause thats really a problem for me wear i live so ya ill start there an read the book u told me to ok clear nights to u aston-martin

[ULtere]

As I'll be after distant objects I assume I'll need a decent mount with some
sort of guidance motor? .... with a faulty light meter that you won’t need for
astrophotography. .... Did anyone help you

[RickJ]

The longer your focal length or greater your resolution (closely tied to focal length) the better the mount must be. What is sufficient for a 50mm camera lens will likely not work with a 80mm ED f/6 (480mm focal length) refractor. And what you need for that won't work with a C-8 at f/6.3 (1260mm). Mounts are usually the weak link in most astrophotographer's equipment. This is why it is highly recommended to start with a simple camera lens and work up from there as you climb the learning curve. There are plenty of wide angle targets to start to keep such a system busy for a long time. When budgeting put the major part of your budget in the mount. One that works well visually may be highly unsuited for the rigors of deep sky astrophotography. Planetary photography puts far less strain on the mount and thus is another good place to start.

Rick