Tasco won’t focus

[Cousin Ricky]

We have a brand new astronomy club in St. Thomas, and a couple of weeks ago, we had our first star party. One child and his grandmother showed up with a Tasco 420x60 refractor. They obtained it in the usual manner: it was gifted to them.

I was prepared to focus on the positive, and give them tips on how to make the best of a scope that I don’t think much of. Not having peered through a cheap refractor in probably more than 20 years, I was taken aback at how shaky the view was on the “sturdy” tripod, though not at all surprised.

What did surprise me was that the telescope would not focus. It was clear in which direction I had to turn the knob, but the focuser simply would not rack in far enough to get stars into focus. A star diagonal was used. I don’t recall which eyepiece was used, but I guarantee it was not the 4 mm.

Does anyone have experience with this model, or know what might be wrong? I am not mechanically inclined.

[geckzilla]

Shoddy craftsmanship? I dunno. The instruction manual doesn't mention much, but possibly going through the assembly instructions over again might help find a solution. Perhaps it was improperly assembled.

[Fred the Cat]

It does make you wonder if the rack and pinion gear got "off track" somehow and now isn't in the proper focus range

[Chris Peterson]

We have a brand new astronomy club in St. Thomas, and a couple of weeks ago, we had our first star party. One child and his grandmother showed up with a Tasco 420x60 refractor. They obtained it in the usual manner: it was gifted to them.

I was prepared to focus on the positive, and give them tips on how to make the best of a scope that I don’t think much of. Not having peered through a cheap refractor in probably more than 20 years, I was taken aback at how shaky the view was on the “sturdy” tripod, though not at all surprised.

What did surprise me was that the telescope would not focus. It was clear in which direction I had to turn the knob, but the focuser simply would not rack in far enough to get stars into focus. A star diagonal was used. I don’t recall which eyepiece was used, but I guarantee it was not the 4 mm.

Does anyone have experience with this model, or know what might be wrong? I am not mechanically inclined.

Could be a lot of things. The focal length of the objective might be wrong (bad optics). The tube might be too long (shoddy construction). The thing might have been designed to not use the diagonal (bad accessory).

Not sure a scope like this is worth spending much time on, but if a fix is desired the easiest is to remove the objective cell and the rear cell, and slice off a bit of the tube (make it shorter). Then put everything back (you'll need to drill new cell mounting holes in one end).

[neufer]

The focal length of the objective might be wrong (bad optics). The tube might be too long (shoddy construction). The thing might have been designed to not use the diagonal (bad accessory).

Not sure a scope like this is worth spending much time on, but if a fix is desired the easiest is to remove the objective cell and the rear cell, and slice off a bit of the tube (make it shorter). Then put everything back (you'll need to drill new cell mounting holes in one end).

Before shorting the tube you should test to see if you can focus on nearby lights (which require a long tube).

If even nearby lights don't focus then shortening the tube for stars won't help.

[Nitpicker]

Were you using the Barlow lens with the diagonal? From the manual:

TELESCOPE ASSEMBLY INSTRUCTIONS

6. Insert diagonal (D) into the focus tube (C). Secure by tightening small retaining screw on the focus
tube (Fig. 4).
NOTE: Diagonal is only to be use in combination with the eyepieces (oculars). Never use the
diagonal and Barlow at the same time.

[Cousin Ricky]

Were you using the Barlow lens with the diagonal? From the manual:

TELESCOPE ASSEMBLY INSTRUCTIONS

6. Insert diagonal (D) into the focus tube (C). Secure by tightening small retaining screw on the focus
tube (Fig. 4).
NOTE: Diagonal is only to be use in combination with the eyepieces (oculars). Never use the
diagonal and Barlow at the same time.

I don't recall the Barlow being used, but I'll check it out the next time we meet.

We were supposed to meet the night you posted this, but the event was postponed due to weather. It's just as well, because I wouldn't have gotten your message in time.

P.S. Chris, I wouldn't feel comfortable taking a drill to my own telescopes, let alone someone else's.