Tracking with a Firstscope 102 AZ

Hello,
Being quite new to the hobby I find myself in a bit of a fix. I bought a Celestron Firstscope 102 AZ which is a short tube refractor (4", f4.9). I have been trying to observe the planets, particularly Jupiter and Saturn but at high magnifications they very swiftly drift out of my field of view. The Alt/AZ mount is equipped with slow motion controls(cables) but I'm finding tracking these objects to be a feat of coordination far beyond my capabilities. I am considering purchasing an equatorial mount with tracking motors but the price of a sturdy mount(the 102 AZ weighs about 17 and a half pounds) is quite high and I'm wondering if I should just sell my whole set-up and buy a SCT with some of the bells and whistles to track and find objects instead of modifying my existing scope piecemeal. It seems that it would cost close to the price of a 4-5" SCT, plus the aggravation to jury-rig my refractor to do the same thing. Any suggestions? I now know that I probably should have done this research before buying a scope in the first place but this refractor does give some beautiful, crisp images. Thank you for any advise, Joe M. in Northwest CT.

My first scope was an alt-taz so I can definitely hear the pain in your voice, when you describe the trials of tracking with yours. As far as buying an SCT I would have to ask what you really want to do with the scope. If you are planning on sticking with planetary observing maybe the ETX Maks might be more in line with increasing your ability to stay with a planet while at the same time giving a fairly sharp view. The maks have a much smaller secondary mirror leading to a sharper image. All that being said if you want to get into Deep Sky observing too, then you are better served with an 8" SCT or bigger, bigger being the key word though, heavier and more bulky to move around. Will be interested in what others have to say on the matter as well though.

Joseph:

With some practice you should be able to track the planets reasonbly well with your 102AZ. What sort of magnification are you using? With a 4 inch scope the maximum magnification would be around 200x, optimal with a 102mm F5 would be somewhere down around 100-150X.

I am quite sure the 102AZ Optical Tube Assembly does not weigh 17.5 lbs. I just put my 102HD OTA on the scales and it weighs about 7lbs and is twice the length. MY guess would be that the entire 102AZ, mount and all weigh 17 lbs. There are plenty of mounts that are reasonably inexpensive that offer tracking that will hand the 102AZ.

As far as chucking it all and buying an SCT or MAK, I suggest taking it a bit more slowly, looking around a bit, maybe go to a star party, a club outing. Get an idea of what is available and what seems reasonable.

There are not perfect scopes. MAKs, SCT's and Newtonians require time to cool down before use, they require collimation and have a central obstruction that compromises the view. A MAK has a long focal ratio and offers very narrow fields of view, the maximum possible with the ETX-125 is about 0.8 degrees, about 1.6 times the diameter of the moon.

You might find that what you have is just perfect, once you get a little experience with tracking. Otherwise, after looking around a bit you might find that something else will do the job better.

Jon Isaacs

Joseph,

As has already been mentioned, you can easily find an eq mount with a tracking motor (only really need one for the RA axis) that will handle your scope. The Orion Astroview (AKA Celestron CG-4) would be a very good choice, and you can probably find one used on Astromart with a motor for about $150-$200. You could put beefier tripod legs on it if necessary.

As for a Goto mount, a Meade LXD55 mount would be plenty of mount for your scope. Goto mounts can be frustrating to some though, and if you are primarily using your scope for easy to find objects, this is really just added baggage and expense. Plus learning to find the brighter objects in the night sky on your own is really part of the observing experience in my book.

Also, it will be no problem at all mounting your scope on an eq mount. No need to worry about having to jury-rig something up! Depending upon the mount, the existing rings will either just bolt directly to the top of the mount (e.g. Astroview, CG-4) or will attach to a dovetail bar (~$15-$20 from Orion) that slides into the top of the mount.

Anyway, best of luck!
Tim
P.S. If you haven't done so already, learn the constellations and the locations of some of the brighter Messier objects; then take your scope out to the darkest skies near you and enjoy the views! Your scope is really intended to showcase large extended objects and star clusters, and will be excellent for just sweeping the Milky Way!