Posts Made By: Alex McConahay

Click on the little yellow birdie looking through the big, undermounted refractor under the word "Anacortes" at the left of the screen.

Type "Piggyback" into the search box, and tell it to go find you a bunch of piggyback adapters.

Alex

A long focal ratio gives more magnification, and a narrower field of view. You see less of a sky, but whatever you are focused on looks bigger. This is good for planets, double stars, or any time there is a small object.

A short focal ratio gives less magnification, but a wider field of view. This is more important on larger objects like large gas clouds (nebulae) and open star clusters.

Now, it is true that the amount of magnification you get is mostly dependent on the eyepiece you choose. So, you can change the field of view, and the magnification by changing the eyepiece. However, if you already have a long focal length, you would need an exceptionally long eyepiece to get a low power view. So, it is better to have a shorter focal length to start with if you mostly want wide-field views.

Now, there are other considerations, also. A long focal length minimizes false color, and can ease collimation problems. However, it can seriously lengthen the tube. But that is not always true (as, for instance, with a Mak, which is folded. Also, you have to consider the relative focal ratios, or F-ratios, which relate the aperture to the focal length.

Alex

I'm surprised that nobody mentioned a middle ground--a standard GM-8 (although a G-11 would be better for a big Meade SCT) with a set of digital setting circles.

I think a Gemini goto is more accurate for astrophotography purposes, but for just finding the territory, a set of DSC, for about $400 would connect to the computer and all that.

Alex

Yes, it is hard to believe if you stake all your hopes on any given piece hitting the another small object like the earth.

But what if there are thousands of pieces?

And what if instead of hitting a small object 8000 miles across, one of those rocks wandered into the perhaps million mile across diameter of earth's gravitational attraction? The actual target is not 8000 miles across, but a million miles across.

It is not quite so hard to believe.

Alex

Not that you are not welcome to ask here--but you may get more hard core responders down in the Home Observatory forum down below.

Alex

Just as an experiment, try not putting the eyepiece all the way in. Leave it out 1/4 to 1/2 inch. Not so much that you are not confident it will hold. Then try focusing again. Try to determine just how much you need. It could be that a simple extender will do the job. These are available for pretty cheap.

Alex

Can you just drill yours where the protruding bolt is? Or is it a larger area?

Alex

Looks good.

Alex

Looks like you had a good weekend. I tried the Rosette and M46 both this last Friday, but neither came out very well.

Congratulations.

Alex

Try having your buddy hold the telrad to the tube while you look through the eyepiece, and then the telrad, and then the eyepiece, and the telrad, and so forth. Is it a comfortable transition. Just decide where you want it by what makes it easy for you to move from eyepiece to telrad.

I would try to keep both the telrad and the magnifying finder.

Alex