Can anyone fix my Unitron?

Hi All

I have a nice little Unitron 60mm, trouble is that true to Roland's post about Unitron lenses it's only about 1/2 wave on the star test and won't take high powers very well. It's probably astigmatic as well.

I would like to use it as a grab-and-go scope. So the point is this: does anyone know how I could get the lens refigured to a decent level without paying some NASA subcontractor $50,000 to do it?

Thanks for your suggestions.

Roger: I believe this may be the post you are referring to:

http://www.astromart.com/forums/viewpost.asp?forum_post_id=588027&poll_id=&news_id=&page=

What about just replacing the objective? Top quality 60mm objectives are pretty rare I guess but it might be easier to start out fresh.

Jon

$50,000 is a bit excessive, but if you are prepared to spend about $600 to $700 I would recommend getting a used Takahashi FC or FS60, this little grab & go scope is the best 60mm refractor out there, it is an apo, and , if for any reason you did not like it you can sell it for what you paid for the little thing fairly quickly.

Vahe

Hi Roger,
You may or may not want to go this route, but I looked everywhere for a 60mm f 11 lense. When I got my Unitron the lense was cracked and I finally found one on telescope warehouse. I took the lenses out and put the Meade one's in and it does a good job. I didn't have the opportunity to have my Unitron lenses refigured but these were fine.
http://cgi.ebay.com/60MM-F11-Meade-telescope-objective-Lens-NEW_W0QQitemZ230423192834QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item35a64ae502
Unless you luck up and find it somewhere else this is the only one I could find bu that's been a couple year's back.
Good luck,

Darrell

It may not need re-figuring. Most of the Unitron
lenses I've seen could be greatly improved by
re-spacing the elements. Mild amounts of coma
and astigmatism (1 - 2 waves) can be adjusted out
by replacing the spacer tabs (sometimes wedging
the airspace), rotating the elements, and/or
tilting the lens assembly. Spherical error
is more difficult to fix unless one of the elements
is in backwards -- which can happen. Sometimes
stopping it down slightly by 5% or 10% in diameter
can also make a nice improvement.

Adjusting the elements is mostly a matter of trial
and error, but aided by some knowledge of what change
will fix what. If you can set up an artificial
star indoors (maybe 30 to 50 feet away) and
work carefully and take notes, you can probably
handle it yourself in a few hours. I've sometimes
thought to write-up a "how to" guide on re-spacing
these -- maybe I will if I find spare time.

Another strategy is to replace the lens. The 60mm
Unitrons come up for sale all the time on
the Evil Big Auction Yard. But the probability
of getting an optically perfect lens on a
randomly selected scope is not too good. Unless
yours is really terrible or has significant damage,
this might not be the best approach. It is easy
to end-up with a lot of scopes needing repair or
adjustment, and none being perfect.

As for re-figuring the lens: most folks with the
required talents would rather be doing something
else than fixing 60mm lenses. At some
time in the distant past D&G Optical in PA would
do restoration work on Unitrons, but I understand
they no longer handle this.