Posts Made By: Randy Roy

You can take exposures at prime focus up to about 30 seconds without a wedge. Beyond that, field rotation will ruin your images. This means you can do some DSLR imaging or webcam imaging and get decent results without a wedge (stacking lots of short exposures). However, if you want to do long exposure imaging (beyond 30 sec) with a cooled CCD camera or film camera with a fork mounted scope, you will definitely need a wedge. Alternately, you could use a field derotator, but they are fairly expensive and frankly, I prefer the results from a wedge.

Best wishes with your imaging.

Randy

Here's a nice picture of one:

http://home.att.net/~telescopebluebook/other/celestron.htm

Lois,

It sounds like you have quite a few scopes which implies a good level of experience, so please take no offense to this, but if you can't even see M42 (generally an easy naked eye object) with three different scopes, with three different diagonals and three different eyepieces, chances are you are doing something wrong at the most fundamental level. I would check things like lens caps, finder scope alignment and also make sure that what you think is M42 is indeed M42. (e.g., are you observing this recently before midnight? If so, it probably isn't M42).

Is M42 the only object you are having difficulty with? If not, try these scopes on a terrestrial object during the day to make sure you have no basic issues with alignment, setup, etc.

Best wishes,

Randy

Joel,

Have you considered DSLR imaging? By stacking numerous 30-60 second shots, you can get some decent unguided prime focus images without critical polar alignment and with fairly high periodic error. I highly recommend it for mounts that are not really made for long exposure prime focus ap/imaging.

Best wishes,

Randy

When just starting out, our expectations are so shaped by the marketing and advertising that we've seen. For the most part, an 8" SCT will never give you visual images like those great color pics you see in the magazines. But, it will show you a lot. I agree with Tom, that with experience you see more. I have a 16" dob that gives great views (though not like the pictures in magazines) and it has been my teacher. I thought once I got it, that anything less than 16" would no longer satisfy. However, that turned out to be not true. The more I learn about the objects I see and the more I see them, the more I appreciate their beauty and intricacies at all apertures. I can still take my 3" APO to a dark site and stay busy all night going from one dso to another. The 8" SCT will do the same and even more so.

BTW--A 30" scope will blow your mind, but still not give you pictures like in magazines and catalogs.

Best wishes,

Randy

I'd like to see a movie about "Ray" York and his struggles to be an astronomy mogul while standing in the shadow of his brother Herb, who changed the face of popular astronomy.

Randy

I don't know how one could possibly use it, but this should couple a 55 plossl's 48mm thread to a 52mm filter.

http://www.bhphotovideo.com/product/11626/BWSUR4852/REG/420/B+W_48mm_to_52mm_Step-Up_Ring_(Lens_to_Filter)_#8a

Randy

A big honkin' tractor beam, Scotty.

Randy

I love my APO for wide field visual and imaging, but you might be disappointed in its ability to deliver deep sky images, especially faint nebulae and galaxies. But, if your primary interest was imaging, I would say go for the APO.

If your main interest is high resolution visual observing of planets and deep sky, you cannot (IMO) beat a good dob. I would get at least a 10" or go as large as you can and be comfortable managing yourself. I have a 16" Starmaster and its performance on deep sky and planets is superb. You can also get superb views from many other manufacturers (how's that for trying not to start anything here? :>).

If your interest is portability, you may find your 8" SCT to be fairly portable. It is at least as portable, IMO, as a 4-5" APO on a GEM and probably more portable. If portability is a real issue, go with a 3-4" APO on an alt az mount, but then you lose on high res planetary views as well as deep sky.

I would consider all these criteria (others will probably add other decision points), decide what's important to you and make a choice best on that. Too bad there is no such thing as a highly portable, large aperture scope that is good for visual as well as deep sky. Some may think they've found it--good for them! Manyof us settle for eventually owning two or more scopes that complement each others capabilities.

Best wishes,

Randy

Oops, forgot. . .