42 replies to this topic

[Kasmos]

This was my biggest telescope mistake, so far.  An eBay purchase, a momentary lapse of sanity.  When it arrived it didn't even have an complete objective, just the crown glass.  The tripod was an old wooden photographic one somehow converted for the telescope.  I did end up fitting a Zeiss Jena Telementor lens to the OTA and 3D printed a .965" eyepiece holder on a new brass focusing tube.  The old girl became a highly usable telescope and is  currently residing in a family with two smart young daughters who are on their way to becoming astronomers.            

 

Mistake? I have a feeling that's the type of mistake, a lot of us wouldn't mind making. 

[Kasmos]

I put lots of time into this one, convinced it was an Asahi-Pentax.... it wasn't.    very slight differences between focusers, but more obvious differences between whatever brand objective this had (there was no maker's mark) and an Asahi.

 

I finally gave it away.

 

Looks just like a real telescope though, doesn't it!

 

DSCN0536.JPG

Too bad, sure looks pretty.

The weird thing is, I have a Selsi f/800mm lens in a cell like that and it seems to be as good as my APL Manon and SYW Mayflowers.

[roscoe]

That one was a Selsi brand also, but nowhere on it was any sort of maker's mark....but when I built my ronchi tester, the best I could get out of the objective still looked sorta like a plate of spaghetti.

 

I think that, with a lot of those scopes, it was luck of the draw, and now and then, a near-perfect objective happened.  You won that lottery!

 

Your scope above, which was almost certainly made in India, was up there on the 'big loser' list..... those folks, who of course could build world-class glass if they wanted, could also put out vast quantities of wannabee stuff, often working with whatever materials they could scrounge up, like that tripod.  That one was made to look at, not look through.  The objective was likely the glass from a magnifying glass, probably plain old window glass.

You carried on that tradition, working with materials scrounged up to build yourself a real nice scope!  Did you re-mount it?

[deSitter]

 I'm remember going to  a star party and looking at a homemade Newtonian were  the elliptical diagonal was glued on 90 degrees from how it should be ie the major axis went side to side instead of up and down. 

 

                          - Dave 

ROFL sadly it would sort of work!

 

-drl

[DAVIDG]

ROFL sadly it would sort of work!

 

-drl

 When I purchased my 4" Criterion Dynascope from Ebay it arrived with a replacement diagonal as well. It was glued on so the reflective surface was  down ie as a second surface mirror  !  Why not, typical bathroom mirrors are that way ! 

 

               - Dave 

Edited by DAVIDG, 12 July 2018 - 09:50 AM.

[tim53]

I shouldn't post this, because this is otherwise an excellent telescope.  Dave even did the final figuring on the mirror at the class because I was running out of time.

 

But the rotating rings are just too thin.  They work well enough, but they're too flexible.  I need to build a ring cage like I did for the 8" f/9.

 

 

[deSitter]

I have never had a dog - and only 1 cat Well I have a 60/400mm Towa that's only useful as a finder, but two others that are excellent so it's just "challenged" Honestly, I have 1 50mm classic that is excellent, 5 60mm classics that are all excellent, two 76mm same, one 90mm same. All excellent. The 60/800mm Towa is outstanding other than a slight issue with ghosting.

 

-drl

Edited by deSitter, 12 July 2018 - 09:40 AM.

[DAVIDG]

I have never had a dog - and only 1 cat Well I have a 60/400mm Towa that's only useful as a finder, but two others that are excellent so it's just "challenged" Honestly, I have 1 50mm classic that is excellent, 5 60mm classics that are all excellent, two 76mm same, one 90mm same. All excellent. The 60/800mm Towa is outstanding other than a slight issue with ghosting.

 

-drl

 Speaking of dogs, a good friend and observing buddy has two black labs. Great dogs, very friendly and great to have around when your observing in the wild.  Just got to be careful since  tripods are  a substitute for fire hydrants in the eyes of dog !  

 

                - Dave 

[Jon Isaacs]

My biggest classic mistake:

 

 

The story behind the scope is convoluted.  Someone was having a moving sale on Craigslist and advertised: Telescope.. That was all.  I replied, the seller eventually got back to me and said her husband had checked it out and something was wrong with it so they would just give it to me.  

 

I didn't know what it was, I just wanted out of the deal but felt obligated so I begrudgingly went to see it, thinking it was some junky plastic scope.  When I saw it, I was very surprised and wished I had had more than $20 in my pocket, which I forced on them.  When I got home and tested it, there was something wrong, the objective was incorrectly assembled.  I straightened that out and it turned out to be an excellent scope. 

 

The big mistake:

 

During a period telescope reduction I gave it away.  

 

Jon 

[wfj]

Let me guess - you judged it against something like an ED 66 (or 72) and found it lacking ?

 

Wouldn’t you likely make the same decision...again?

 

Saying this ... because it’s what I go through when the “herd” worries me.

 

How does one have enough, when one worries of “too much”?

 

This affliction happens to me in other walks, like engineering, design, writing papers, etc.

[wfj]

 I'm remember going to  a star party and looking at a homemade Newtonian were  the elliptical diagonal was glued on 90 degrees from how it should be ie the major axis went side to side instead of up and down. 

 

                          - Dave 

Had that in addition to the optics being also figured exactly backwards (perfect oblate spheroid -200% out of correction f/6), on a exactly backwards balanced scope. Picked it up from a guy who had gone to the same telescope making class, same components, consistently wrong. He was giving it away because it was too much of a burden, as he couldn’t face figuring out why it had gone wrong. Nor did he care to, his “backward” approach extended to his entire life (as he explained), and it was too much to change late in life. Still affecting me just thinking about it.

[Kasmos]

That one was a Selsi brand also, but nowhere on it was any sort of maker's mark....but when I built my ronchi tester, the best I could get out of the objective still looked sorta like a plate of spaghetti.

 

I think that, with a lot of those scopes, it was luck of the draw, and now and then, a near-perfect objective happened.  You won that lottery!

 

Your scope above, which was almost certainly made in India, was up there on the 'big loser' list..... those folks, who of course could build world-class glass if they wanted, could also put out vast quantities of wannabee stuff, often working with whatever materials they could scrounge up, like that tripod.  That one was made to look at, not look through.  The objective was likely the glass from a magnifying glass, probably plain old window glass.

You carried on that tradition, working with materials scrounged up to build yourself a real nice scope!  Did you re-mount it?

I bought my Selsi lens from Sheldon, it's a long story but it was advertised as a Carton.

 

Just incase there's a misunderstanding, the brass scope isn't mine, it's Ben's from post #19. I was commenting on it so it shows in my post.

[roscoe]

I bought my Selsi lens from Sheldon, it's a long story but it was advertised as a Carton.

 

Just incase there's a misunderstanding, the brass scope isn't mine, it's Ben's from post #19. I was commenting on it so it shows in my p

I've had 100% good luck with Sheldon stuff, the Carton 70mm I got from him is just fine, as has been any other stuff.....

 

And....oopsie, there's the problem with skimming the messages, not the first time I've replied to a reply instead of the original poster......

[steve t]

 Speaking of dogs, a good friend and observing buddy has two black labs. Great dogs, very friendly and great to have around when your observing in the wild.  Just got to be careful since  tripods are  a substitute for fire hydrants in the eyes of dog !  

 

                - Dave 

Never had that problem, but we have four small dogs, two Shih Tzu's, a rescue,  and a four month old Poodle. Walking in the backyard at night is a little like crossing a puppy mine field .

[Kasmos]

Never had that problem, but we have four small dogs, two Shih Tzu's, a rescue,  and a four month old Poodle. Walking in the backyard at night is a little like crossing a puppy mine field .

That's potentially a lot of Shih Tzu to avoid. 

[Jon Isaacs]

Let me guess - you judged it against something like an ED 66 (or 72) and found it lacking ?

 

Wouldn’t you likely make the same decision...again?

 

Saying this ... because it’s what I go through when the “herd” worries me.

 

How does one have enough, when one worries of “too much”?

 

This affliction happens to me in other walks, like engineering, design, writing papers, etc.

 

No.. I had judged against a WO 66SD and found the 60 mm Asahi-Pentax to be the better scope.  But it wasn't getting much use and taking up space.. And it deserved someone who would restore it properly.

 

Jon

[clamchip]

Nearly 40 years ago we used to have a parrot, his name was Perrico, a rather large

Orange Wing Amazon.

He would see the dogs eating, and hear the crunch crunch crunch down on the floor.

So he would get down on the floor and make crunch crunch crunch noise too, only he

was chewing on the baseboard molding!

I would often attach large tree branches to his cage, he spent more time outside the cage

than inside, and he would climb and carve up these branches.

One day he decided to practice his woodworking skills on my Edmund Scientific 4 inch

equatorial refractor tripod. I got it a little too close I think, making those maple legs fair

game.

 

Robert

[Geo31]

Nearly 40 years ago we used to have a parrot, his name was Perrico, a rather large

Orange Wing Amazon.

He would see the dogs eating, and hear the crunch crunch crunch down on the floor.

So he would get down on the floor and make crunch crunch crunch noise too, only he

was chewing on the baseboard molding!

I would often attach large tree branches to his cage, he spent more time outside the cage

than inside, and he would climb and carve up these branches.

One day he decided to practice his woodworking skills on my Edmund Scientific 4 inch

equatorial refractor tripod. I got it a little too close I think, making those maple legs fair

game.

 

Robert

 

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