FINALLY GOT AN ASTROSCAN

I'll bet many are curious about those Edmund Astroscans that came out 1976 and was produced thru Y2013. The 4+ inch f/4.2, "red ball" telescope . I just got one used here to examine it and try to understand the mistique and assess its build and performance. Right out of the blocks, a little sobriety here: It is Definitely a kid's "toy" Christmas scope both cost and target market; A cute, durable RFT. New cost was around $250 for the entire package; used now floats around $100, which is about what it's worth. The literature that comes with it is profuse! Noteworthy is the clamed parboilc PM 1/8 wave and SM (folding flat) 1/8 wave. The SM is mounted on a flat window; no indication regarding the optical quality of the window, though. I looked in from the front and the eyepiece side... YIKES! The fixed, factory alignment is WAY off! So bad that even bothering to quantify it would be pointless... so ~sigh~ there. Then I notice what (deja vu) I had seen with other cheap RFTs: The long, skinny focuser tube and undersized SM vignette so much that the whole PM cannot be seen from the image side. Is this a mistake? I don't think so. It assures that, even if the optics are grossly misaligned, the vignetted sampling of the PM will at least still see the full (albeit constricted) operational ~f/6 AKA "aligned well enough?" This of course manifests as the 3-inch entrance pupil displaced laterally on the (now oversized) PM. In my case, it is displaced so badly that it indeed clips over the edge of the PM. But note also, that the imagery may indeed be sharpened by (intentionally?) clipping the PM like this). One would then suspect that maybe the scope was properly aligned when it came from the factory; I doubt it. This thing is so glued together that said kid could kick it down the stairs and it would maintain. EVERYTHING is glued in. Well, you would think that after this examination... I would have at least taken it out so see how it works. Not yet, it's been snowing. But I intend to do that and report back. I expect it will perform "sorta OK" at the very low 25x delivered by the provided eyepiece. And THAT would be worth $100. So here I get a bit sneaky... If they are all like this... what if I were to replace the PM with a really good one, mount a good, properly-sized SM on a stalk/spider, elim the questionable window, and of course critically align PM/SM/focuser... and install a great eyep (Delos 17.3?). The imagery would be astounding! I would actually do that, except there seems to be no way to dismember this thing witoud demolishing it! Tom Dey

Tom,
My readings on those is similar in that the factory collimation can be quite poor and it can't be adjusted by the user.It used to be supplied with the RKE 28mm kellner eyepiece which had a problem with blackouts. Some samples are probably better than others but given the inability of a user-fix on these, it's buyer beware...

I bought one at a pawn shop many long years ago for $90. They thought it was a radio....

Anyway, it worked fine and gave very pleasing views of the moon and low power deep sky. Bought it before the last swing through by Halley's Comet. Went out near Joshua Tree National Park and set the scope up for friends to see the comet. It was a wonderful experience for everyone, enhanced by the little scope.

Almost sorry I sold it.....but a Cave 6" RFT has that base covered now!

UPPDATE: I just cut a deal on another used one! Should arrive within a week? Come Hell or High Water, one way or another... I'm determined to wind up with a "good" one! Stubborn that way. Tom

I certainly wouldn't call it a "kid's toy." It _can_ be a decent RFT. In some senses it has been obsoleted by Chinese scopes like the StarBlast with better focusers (sometimes) better primaries, and collimatable primaries. But not in all ways.

No one has yet bettered its basic industrial design. It is perfectly suited to hand-holding it while scanning the skies.

Its liabilities? I have never seen one with a 1/8th wave primary and precious few that meet 1/4 wave. While the non collimatable primary mount CAN be OK, it's not unusual for the scope to get out of alignment as it ages. It can be collimated, but it is not a picnic. The focuser's problems are far more grave than just a skinny draw-tube: it is a lousy focuser.

None of these things really prevent the scope from doing what it was designed to do, providing spectacular low power views given its modest cost, even back in the 1970s.