Posts Made By: Dan Huang

Is their any cheap binoviewer that could be used on an etx maksutov. Like around the 200, 300 dollar range. Maybe not first class views, but with some decent views on the Moon and the brighter planets. Along with that, what are generally eyepieces to avoid with a binoviewer.

I am hs student new to astrophotography and recently I bought a SAC-IV imager and laptop to get me started. Last night, I was trying to get a quick image of the moon through prime focus and all I saw saw a large white glob on my screen. I turned the focus knob on my etx 90 back and forth and still the image failed to focus. I tried focusing earlier in the day on some pine trees in my neighborhood and was able to focus. I don't see what am I doing wrong. These forums are the only place I can turn to because nobody I know is into this hobby.

Which is better, plate glass or pyrex for an 8 inch telescope?

I was looking at secondaries from protostar and noticed that the quartz mirrors were twice as much. What exactly is the difference? Is it worth the money, or is there almost no difference from quick glances?

I have an etx-90 and am debating between one premium eyepiece, or like three value/quality eps(like the ultimas). With such a small apature, will the premium ep really excell over the mid-price ep, or is it a waste of money?

I am starting on my first telescope making project, attempting to make a 6 inch f8 closed tube dob from scratch. I have looked around for the best tube option and of course I always see sonotube as the easiest and cheapest solution. I would think that a metal tube like aluminum would be the best, but the cost of the tube itself and having someone custom cut it would be way to much. I found a website that someone used rocket tubes for their telescope. Would phenolic material they use for model rocketry be up for the job? I supposedly waterproof and fairly durable and comes in the right size (7.5 ID and 4 ft long) but nobody ever really recommends it (at least I have not seen anything). Does that mean something is wrong with it? Should I just use sonotube? Also the rocket tube is only 48 inches long, so would thatbe cutting it too close for an 6 f8?

Does anyone know how the new astrola mirrors match up against other quality mirror optics? The price alone shows that the opticians think it's worth something. It says on their website that the mirrors could produce diffraction limited images. How good do the optics have to be in order to be diffraction limited?

Who supplies good quality 4-inch achromats in long focal lengths (12 or 15 or so). Looking for something like this from d&g optical, but they only carry 5-inch and up. Needs to be a high quality 4 inch lens with cell. If you can point me in the right direction, it would be greatly appreciated.

Is there a way to reduce the apeture of a commercial refractor (such that of the new cheap Meade LXD 55 telescope) to reduce false color? I have heard that it was an old way ATMers could make semi-apo scopes back in the day. Then I guess a minus violet filter could be used to reduce the remaining color. Is it possible, because a solid 3.5 inch sharp unobstructed refactor with go-to would be grand.