134 replies to this topic

[deSitter]

OK, got it setup. The lift table made it easy. There are issues:

 

1.) I cannot polar align it because the mount head wants to flop down as soon as I try to tilt it that way. There is too much weight for the pivot to hold up.

 

2.) There is not enough counterweight to balance on the polar axis. I will need to dig up the counterweight from my 10" Starfinder EQ mount and see if it will fit the shaft. If not, then maybe a Cave counterweight will work. Of course, this will make number 1 worse.

 

3.) The finder mount puts the finder too close to the telescope tube. Either that or my head is too big.

 

I did a rough collimation and then I glanced at Saturn, but it obviously still needs to cool down some more.

 

Next will be to get the Magellan II system working.

 

Starfinder 16 EQ Setup.jpg

This is a very fun project. Keep at it, you will be rewarded. Others have struggled with that neck pivot and found solutions.

 

-drl

[cavedweller]

The mirror may need to go back some as there were holes to move it up and down.

 

Actually, I thought the same, but the three sets of three bolts hold a bar that has a stud on the end and the mirror mounts to those three studs.

 

I found in the box of accessories a screw-on extension that I thought was an eyepiece barrel, but actually fits on the drawtube and the eyepiece retainer ring fits onto that. I will use that tomorrow night.

[CHASLX200]

If you got a old barlow take the lens out and try to focus and it should take care of that prob.

[cavedweller]

All of them type of mounts had the worst way to try to adjust the polar axis.  Just very crude and them tiny set screws dug into the metal. At  least Starliner had a better way to do it. I always called them scopes a train wreck scope as it was a wreck before you ever took it out of the boxes. Not picking on your scope.

 

That mount is not meant for a OTA bigger than 8" really.  Would be great for my 826.

 

I have an 8" RG with what appears to be the same mount. When I first saw this one while picking it up, I thought, oh-no!

[cavedweller]

This is a very fun project. Keep at it, you will be rewarded. Others have struggled with that neck pivot and found solutions.

 

-drl

 

Actually, I am already convinced that this OTA deserves a much better mount.

[CHASLX200]

I have an 8" RG with what appears to be the same mount. When I first saw this one while picking it up, I thought, oh-no!

They are the same about.  Just a shorter pier and no bearings i think in the DS mount.  I have given up on finding a mount for my 826. I may have a seller coming to FL with a CI700 and i hope i can use it for the Fracts and 826 if i can rig it up  to work on a short pier.  These classic Newts are just never in FL.

Edited by CHASLX200, 17 September 2023 - 07:27 AM.

[CHASLX200]

Actually, I am already convinced that this OTA deserves a much better mount.

Needs a AP1200 and no ess.  Sometimes you can find a non GO-TO AP1200 for around $3k  If you were local i would give ya 600 for the DS mount.

[cavedweller]

If you got a old barlow take the lens out and try to focus and it should take care of that prob.

 

I had to do that with a Parallax refractor on the first night I had it out. That focuser was 5" too short. This one is only about 1" too short and I found the 2" extension, so that is now solved.

[cavedweller]

They are the same about.  Just a shorter pier and no bearings i think in the DS mount.  I have given up on finding a mount for my 826. I may have a seller coming to FL with a CI700 and i hope i can use it for the Fracts and 826 if i can rig it up  to work on a short pier.  These classic Newts are just never in FL.

 

I wonder if the heat with humidity led to an early demise for older stuff in FL.

[cavedweller]

Needs a AP1200 and no ess.  Sometimes you can find a non GO-TO AP1200 for around $3k  If you were local i would give ya 600 for the DS mount.

 

A Cave Obs mount I think will handle this.

[CHASLX200]

I wonder if the heat with humidity led to an early demise for older stuff in FL.

Not sure why FL never had real scopes.  Odd since we have the best seeing and never any rain in my area anyways. Seems Cali gets the lions share of classic stuff 9 out of 10 times.  There were never even any real scope stores or makers in FL.  I have seen 50 DS 16 mounts for sale and none within 300 miles from me.

 

Best to turn that scope into a Truss Dob.

[CHASLX200]

A Cave Obs mount I think will handle this.

It would be much better, but it also as a small bearing area so still not the best and it weighs a ton.

[cavedweller]

It would be much better, but it also as a small bearing area so still not the best and it weighs a ton.

 

OK, how about the big gun; Parallax HD300C?

 

Here it is with a Cave 12.5", F/6.5 OTA:

 

[CHASLX200]

OK, how about the big gun; Parallax HD300C?

 

Here it is with a Cave 12.5", F/6.5 OTA:

 

Cave on Parallax.JPEG

If you got a way to move it and got the money then ya.  Never seen that mount before.  

[Herchel]

OK, how about the big gun; Parallax HD300C?

 

Here it is with a Cave 12.5", F/6.5 OTA:

 

Cave on Parallax.JPEG

That is awesome , 

[CHASLX200]

Mount must cost 20k and makes that OTA look like a 6".

[jgraham]

A couple of quick thoughts…

 

Meade often sold focusers with a built in extension tube. This extension was removed for prime focus photography, installed for visual.

 

There is an easy fix for a tube that tends to slip in the rings; install a strap between the cradle and the rear end of the tube to bear the weight of the tube when it tries to slip.

 

I’d be tempted to set the polar axis angle before adding the tube.

 

These old Sonotube beasts beg to be rebuilt as a lightweight truss. That solves a _lot_ of issues and makes the scope far more useable. Our club built a 16” f/4.5 with a Sonotube. It worked fine for a couple of year, but as the tube aged and soaked up water it got really heavy and was eventually rebuilt as a truss.

 

Ugh, I’m not flexible enough to use straight through finders anymore. All my scopes get RACI finders these days.

 

Food for thought.

 

Enjoy!

[cavedweller]

A couple of quick thoughts…

 

Meade often sold focusers with a built in extension tube. This extension was removed for prime focus photography, installed for visual.

 

There is an easy fix for a tube that tends to slip in the rings; install a strap between the cradle and the rear end of the tube to bear the weight of the tube when it tries to slip.

 

I’d be tempted to set the polar axis angle before adding the tube.

 

These old Sonotube beasts beg to be rebuilt as a lightweight truss. That solves a _lot_ of issues and makes the scope far more useable. Our club built a 16” f/4.5 with a Sonotube. It worked fine for a couple of year, but as the tube aged and soaked up water it got really heavy and was eventually rebuilt as a truss.

 

Ugh, I’m not flexible enough to use straight through finders anymore. All my scopes get RACI finders these days.

 

Food for thought.

 

Enjoy!

 

What I thought was another eyepiece in an unopened box, was a short extension that solved the focusing problem.

 

I had set the polar angle with a protractor level and then loaded the tube and weights. I walked away to get the finder and when I came back it looked like this:

 

 

Literally lame...

 

For fear this would happen, I tightened the bolts and set screws to the point that I thought the aluminum threads might strip if I went tighter, so I know it was not that I did not snug them enough. This was after I replaced the bolts because the original bolts were too long and contacted each other before they were properly seated.

 

After using the scope for the past three nights, I would say this mount is overloaded by at least double its actual capacity. I have an 8" RG on essentially the same mount and that seems about the right payload.

[cavedweller]

I am happy with the OTA. It was easy to collimate and the light gathering ability and wide field is impressive. There might be a slight amount of astigmatism; I could not get perfectly round airy disks when star testing on Polaris. The long axis of the shape flipped 90 degrees when comparing inside and outside of focus. I have seen this on other scopes that I use without much complaining.

 

Well, time to move on to other things...

[apfever]

What are your intentions with the mount and OTA?  I've harped about that latitude lock being under engineered in several threads, especially my MRG restoration thread. LINK, entry #71 or so and go looking for the wood insert to hold latitude somewhere in the thread too.  That lock is not just the worst of the mount, it is the worst by FAR.  

 

Does this mean you won't be interested in the 2001 catalogue with a ton of the 16" information?  I was going to loan it out for the cost of shipping because there's too much in it for me to duplicate. I took these pictures a while ago but didn't get back to it. Shipping would probably be about $3, maybe two something, by media mail. I might hole punch the catalog so individual pages could be copied. I would eventually want it back as I'll need it, and I'd even cover the shipping to get my own catalog back. 

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Edited by apfever, 20 September 2023 - 08:35 PM.

[cavedweller]

I look forward to mounting the OTA on one of my better mounts. I could retain the straps and bolt it to a Cave Observatory mount. I would need block spacers, so the wingnuts clear the saddle.

 

I would like to get the Magellan II up and running, but at this point it would be to retrofit onto my 8" RG if it will fit. I cannot see myself bothering to use this scope on this mount again. I am considering using my Meade 10" Starfinder on this mount. I usually use the Atlas EQ-G, but I never use the GOTO. I am happy with the dual-axis controls.

 

Thank you for the offer on the catalog, but I already have one of that vintage.

[cavedweller]

It dawned on me; the bolts are clamping the ears together, but the set screws are working against the bolts prying the ears apart. You end up with very little friction hold and only the set screws preventing the rotation. The result being movement and gouging.

 

If I were to try and fix this, I would insert a thick-walled sleeve in the middle and use a grade 8 through bolt and nut, and then tighten it with a couple of breaker bars.

[CHASLX200]

What I thought was another eyepiece in an unopened box, was a short extension that solved the focusing problem.

 

I had set the polar angle with a protractor level and then loaded the tube and weights. I walked away to get the finder and when I came back it looked like this:

 

Polar Axis Collapse.jpg

 

Literally lame...

 

For fear this would happen, I tightened the bolts and set screws to the point that I thought the aluminum threads might strip if I went tighter, so I know it was not that I did not snug them enough. This was after I replaced the bolts because the original bolts were too long and contacted each other before they were properly seated.

 

After using the scope for the past three nights, I would say this mount is overloaded by at least double its actual capacity. I have an 8" RG on essentially the same mount and that seems about the right payload.

They were all pretty sad mounts from all the makers back in the 50's thru the 90's.  A 8" is the most that should have ever been put on them. Well if you ever come to FL i would pay well for the mount.

[deSitter]

I am happy with the OTA. It was easy to collimate and the light gathering ability and wide field is impressive. There might be a slight amount of astigmatism; I could not get perfectly round airy disks when star testing on Polaris. The long axis of the shape flipped 90 degrees when comparing inside and outside of focus. I have seen this on other scopes that I use without much complaining.

 

Well, time to move on to other things...

The huge mirror is probably sagging.

 

-drl

[deSitter]

They were all pretty sad mounts from all the makers back in the 50's thru the 90's.  A 8" is the most that should have ever been put on them. Well if you ever come to FL i would pay well for the mount.

There is little upside in just throwing mass at a problem. Shaft mounts are as obsolete as typewriters.

 

-drl