Posts Made By: Walter Hamler

First, try to download a copy of Newt 2.5. Do a google search. It will help you plug in the pertinent data and make an educated decision.
If you already have a tube that you will be using, and you are sure it is long enough, the simpliest and most accurate way is to go ahead and cut a hole for the focuser at one end, allowing at least 6 to 8 inches additional tube in front for a light/dew shield. Then place the spider/diagonal holder being careful to make sure the mirror is centered under the focuser. Then adjust the diagonal so that when you look down the focuser you can see the open end of the bottom of the tube centered in the focuser.
Now, take the tube someplace where you can view something at least a mile away. Put your longest fl eyepiece in the focuser and rack the focuser out about 1/2 to 3/4 as far out as it will go. Then point the tube toward that distant object and have someone carefully slide the mirror holder with the mirror installed into the rear of the tube until you can see an image sharply. Don't expect the images to look great, you will simply want to establish where the mirror needs to be. Make sure the collimation screws on the mirror cell are at about the half way point. That will give you a little more fudge factor. Carefully measure on the tube where the mirror cell mounting holes need to be then take it all home and drill the holes to mount the cell. Also, one other thing to do first. Use the mirror to reflect an image of the sun against a wall or something that you can simultaneosly use a tape measure to measure from the image to the front edge of the mirror. Make sure that the mirror, the image, and the sun are close to the same line of sight. I typicaly will go out to my mailbox late in the PM (for me) and project the image on a piece of white card I have placed on the post. That allows me to get the mirror , the paper, and the sun in the same line of site and also allows me to clip the end of the tape measure to the post. That distance will be the fl of the mirror to probably within a 1/3" or less if you are careful. On a 6" f/8, it had better be close to 48"! ;-) From the eyepiece to the diagonal will be around 6", maybe 7. So from the center of the focuser hole to the mirror should be close to 42", +/-.

Walt

If you look in the Jan issue of S&T they have a topic on the Hot Items for 2003. One of them is the site you mentioned, in the Miami area. www.preciseparts.com

Walt

That's how I mounted my 4" acromat.

Walt

I believe the local Community College planetarium here has one of those. Our club holds meetings there so I will try to find out if it has "chains" but I'm pretty sure it doesn't. Is this scope red ota and white horseshoe style mount?

Walt

Not in a 6" aperture, the parabola will always be better. Also, the Russians are actually pretty good at optical fabrication. So, yes, I would say the parabola is worth the extra 100.00. Especially if you ever decide to sell the scope, the resale value of the parabola will be much higher.

Walt

I'm no expert, but this is how I aligned my 4" refractor and a friends 4".
I used a laser to shoot a beam out the front through a piece of paper cut to fit the lens. A small hole was cut in the very center of the paper. Then adjust the focuser to center the laser in the small hole. This ensures your focuser is square with the lens.
Then I used a chesire tester to check the colimation of the objective. That is where you see the donuts and you have to move the colimation bolts on the objective to correct any displacement. If you don't have collimation bolts, you would have to check that the elements are square, not cocked somehow, and not held too tightly by the retainer ring.

Walt

I have the 30mm and like it very much in my 10" f/6 and a 4" f/10 refractor. I was just talking with Astro-Systems a few days ago and we got to talking about the WS's. They don't recommend them in f/5 or faster systems as the edges do go soft fast.
Cloudy Nights has an article comparing them to Naglers and the 13mm came out better than the others but still no where near as good. I would suspect that it depends primarily on your value of a fov sharp to the edge (you won't get it with the WS)and how much of a bargain you want. You can't have both.

Walt

Rob, I can't speak for the Tal-3 but the Tal-2M that I own will easily handle 30# plus as I have loaded it to that point. It is a very robust mount and has some rather large bearings and shafts. From the factory it has two shortcomings in my opinion. It uses a 12vac synchronous motor that is weak and noisy, and it uses glue for lubricant. At least that is how it acts.
I completely disassembled mine and replaced two bearings on the worm shaft with higher precision versions, relubed with superlube, and then recently replaced the motor with the drive motors and controllers from a Celestron CI-700 mount.
Now I have a mount that can use PEC and an autoguider, and a variety of speed choices and slew rates. And all this cost much less than 600.00.
The TAL3 uses a stepper motor, and it also uses a 3" center colum where the -2 uses a 4" colume. If possible look into a TAL-2M instead.

Walt

Kokusai Kohki in Japan. They are distributed by several dealers here and overseas.
I have one of the WS-II versions and find it a very sharp eyepiece that is a little soft at the edges, especially at f/5 and faster. However, I don't find it terribly objectionable considering the value price. I believe Apogee is selling off the last of the II's at a bargain price.

Walter

I essentially did what you state when I put a JMI Crayford focuser on a 4" f/10 refractor. You have to make your measurements carefully as the drawtube length is considerably less on a newt focuser as compared to a typical refractor focuser. In my case it worked out for all the eyepieces in my inventory, but only with the 2" diagonal attached all the time. I had a 1.25" diagonal that would not work as the light path through it was enough shorter than the 2" that the ep's would not come to focus.
The Feathertouch crayford for the refractors has the extra drawtube length, but they are PRICEY. The quality is there as well, so you do get a quality unit, but I would only use if it were matched up to a high end set of optics in the first place.

Walt