Warning, 60mm's can be very addicting...
NOW you tell us!!!
Posted 05 May 2023 - 05:24 PM
Warning, 60mm's can be very addicting...
NOW you tell us!!!
Posted 05 May 2023 - 05:31 PM
Posted 06 May 2023 - 03:47 PM
Anyone care to explain the odd focuser design here?
Posted 06 May 2023 - 03:55 PM
Anyone care to explain the odd focuser design here?
You need a lot of focuser travel to reach focus on close terrestrial targets. Older refractors often had short drawtube with a long push-pull tube. Some, like the Tasco 10TE and various versions of the Towa 339, used a double tube design so that the optical tube could be shorter so it could be shipped in a smaller box.
Posted 06 May 2023 - 05:04 PM
Anyone care to explain the odd focuser design here?
The slower the scope the more focus travel you need. An f/4 60mm binocular can get away with 2 inches of travel. An f/15 refractor will need 4x as much. You can either have a very long focuser rack, or a 2-tube system with the coarse focus supplied by a slip tube. That allows the precision part, the focuser rack, to be kept short at the expense of more complexity.
These scopes were sold as both astronomical and terrestrial instruments. An image inverter for terrestrial use eats up a lot of the optical path, so you need correspondingly more inward focus travel. As mass manufacture of long precision racks became possible, the 2-tube focuser became much less common.
-drl
Posted 08 May 2023 - 12:38 AM
The slower the scope the more focus travel you need. An f/4 60mm binocular can get away with 2 inches of travel. An f/15 refractor will need 4x as much. You can either have a very long focuser rack, or a 2-tube system with the coarse focus supplied by a slip tube. That allows the precision part, the focuser rack, to be kept short at the expense of more complexity.
These scopes were sold as both astronomical and terrestrial instruments. An image inverter for terrestrial use eats up a lot of the optical path, so you need correspondingly more inward focus travel. As mass manufacture of long precision racks became possible, the 2-tube focuser became much less common.
-drl
Ok that makes alot more sense now! Thank you
Posted 08 May 2023 - 12:40 AM
I've got to come up with some way to bang dents out of the Ota. And make a mount. Any suggestions?
Posted 08 May 2023 - 07:49 AM
I've got to come up with some way to bang dents out of the Ota. And make a mount. Any suggestions?
Lots of threads here on fixing dents, try this.. https://search.brave...ghts&source=web
Mounts can be found, you just have to be a bit patient.
Posted 08 May 2023 - 02:45 PM
I've had some pretty good success with my own techniques:
https://www.cloudyni...t-removal-tips/
It takes time and patience and isn't easy.
Just two days ago I had more limited success on a C80 tube with a sharper deeper dent.
I could only get it out about half way before before growing tired of it
I think it's a thicker and stronger tube than most 60mm's tubes.
Posted 10 May 2023 - 02:33 PM
I've had some pretty good success with my own techniques:
https://www.cloudyni...t-removal-tips/
It takes time and patience and isn't easy.
Just two days ago I had more limited success on a C80 tube with a sharper deeper dent.
I could only get it out about half way before before growing tired of it
I think it's a thicker and stronger tube than most 60mm's tubes.
Wow those were pretty bad dents. Mine isnt too bad. I fixed a trumpet someone dropped once. Similar techniques
Posted 30 May 2023 - 03:55 PM
I made a dovetail out of wood. I clamped it to the ota with hose clamps at each end of the extra long dovetail and had leftover drawer liner wraped underneath to protect the ota. I put it on a mount and tested it out last night. I found a star field near milkyway i guess near Scorpio ♏ its wasnt amazing. The focuser is quite fidgety and im not used to the concept. The scope seems on the dim side of light gathering. I will try it again tonight and see. If not i probably will get rid of it.
Or pack it away lol.
Posted 01 February 2025 - 09:35 AM
Hi,
Last year, a 291 came up for sale 10km from me. I was in the midst of a family crisis and buying it was the last thing on my mind. Late summer, autumn and mid winter passed and last week I decided to check if it was still available. It was and I purchased it yesterday. It came with a couple of eye-pieces and the #781 drive.
This telescope I will never sell because it is my sign that things have started to get better again.
Clear skies
Posted 02 February 2025 - 12:44 AM
The 291 will resolve the Perforated Thingy.*
I have very few 60's that can do this.
*The Perforated Thingy is a cylindrical cover on a cell tower 2.5 miles from my house, with stamped perforations
that are very difficult to see in anything less than 4 inch aperture.
Edited by clamchip, 02 February 2025 - 12:53 AM.
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