39 replies to this topic

[precaud]

Wanting to make sure I'm posting in the right forum...

I just picked up one of these, made in August of 1985. Looks to be complete, except for the manual, and in very good shape.

Is anyone out there still using one of these?

[rmollise]

Do you want it to be? If so, it is.

I've used enough of 'em over the years if you have a question.

[apfever]

I'd say yes it is. I had one complete, sold it, then ended up with a complete mount I still have. The DS-16 blue tube set up is a classic hernia job. I'd pick up each of the three counter weights sepperately. Even the two small ones together became a chore. The blue tube OTA is probably the heaviest OTA I ever owned.
Typically good optics. My blue tube was good, and my current grab n go 16" truss has the DS-16 optics.

Pictures?

[precaud]

If it's that easy, then yes, so be it.

Rod, I recall seeing your handle show up when I did my pre-buy research. The one I bought was previously owned by CN member "Alleline", there are numerous posts in the archives about it, which was definitely helpful.

My intent was to turn this into a dob, but when I picked it up, I learned that it came with a set of 20" cast aluminum rings, so it makes sense to at least give it a shot on the GEM. I've never owned a GEM, so my questions may reflect that.

The dec motor/gearing appear to be a weak link. I'm inclined to not even use them unless/until I decide I'll stay with the GEM. Make sense?

When I was checking it out, the guy had two extensions AND had the EP pulled out slightly to get it to focus with it racked out nearly all the way. Apparently this thing was originally set up for AP. So it would seem to make sense to either move the primary back or the spider forward for visual use.

Then, when I got it home, I noticed that, at all useful focuser positions, the primary or secondary or both were being vignetted by the thick sonotube. In normal focuser positions, 1/2" or more of the primary's radius is lost.

So I'm thinking to solve both of these, enlarge the existing focuser hole toward the front, make an adapter plate for the focuser, and move the 2ndary vane forward along with it. Make sense?

apfever, I'll post some pics when I can, the OTA is on the floor at the moment. You're right, everything is heavy on this thing...

[Da Bear]

Yes...pic's please.

Da Bear

[rmollise]

Yeah, I'd forget the dec motor. It was only useful, really, for photographic guiding, and the old beast really ain't up to that. I'd replace the focuser with a lower profile one, move the mirror as needed, and probably downsize the secondary.

[precaud]

OK, thanks. The dec can still be tweaked manually with the knob if needed.

Until I commit to this thing, I'd prefer no- or low- cost solutions, so I'll likely fly with the existing focuser for now. So far, I haven't seen any indication that a smaller 2ndary is in the cards. I haven't taken the primary cell out, so I don't know if there's room to scoot it back yet. That would be the simplest solution.

I noticed that the primary is not centered in the cell. Is that normal? Part of it's "offset" collimation"?

PS - I corrected my post above, I meant 1/2" of radius was lost, not 1/2" of diameter...

[precaud]

I figured out how to get the OTA on and off the mount fairly smoothly without a helper. Here's a quick pic.

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[Bob Myler]

I'd say yes it is. I had one complete, sold it, then ended up with a complete mount I still have. The DS-16 blue tube set up is a classic hernia job. I'd pick up each of the three counter weights sepperately. Even the two small ones together became a chore. The blue tube OTA is probably the heaviest OTA I ever owned.
Typically good optics. My blue tube was good, and my current grab n go 16" truss has the DS-16 optics.

Pictures?

Recently picked up its little brother - a Deep Space 10. Meade sold them thru Crown Optics. Mine came with the optional #680 focuser, #530 viewfinder (very nice), #787 motor drive and #55 manual dec control. To reduce weight - its original owner replaced the sonotube with a white fiberglass tube from Parks. MUCH lighter.

The original DS-16 with "Zolatone" coated sonotube came in at 85 pounds for the tube assembly and 140 pounds for the mount - 225 lbs total. The stock DS-10 weighed-in at less than a third of that (72 lbs., tube + mount). The Parks tube reduced that by at least another 15 pounds.

Back in 1983 - a stock DS-16 sold for $1185.00 - while a "stock" DS-10 went for $449.50.

John - while I don't have the original manual for the DS-16 - I do have copies of its promotional literature, original price and options sheet, 14 page Q&A on both models from Crown Optics, plus the 16 page Instruction Manual for the DS-10. If interested in any copies - PM me.

[Don Taylor]

My ds10 also vignetted so I moved the primary down by redriing the attach holes for the 3 bars that attach the mirror cell. I ended up drilling midway between the existing holes and only using 2 screws per bar. Solved all problems.

[TimD]

That sure is a beast! not a grab and go by my definition, I've looked through a couple and the view was not bad. Rod's suggestions are great idea if you decide you want to upgrade it and make it more of a joy to use....I have to admit I used to look at the ad's way back when and dream of having one!

[precaud]

Bob, thanks for the info. Your DS-10 with Parks tube sounds sweet. Very manageable, indeed! What exactly does the #55 manual dec control consist of?

I'll PM you shortly.

[precaud]

My ds10 also vignetted so I moved the primary down by redriing the attach holes for the 3 bars that attach the mirror cell. I ended up drilling midway between the existing holes and only using 2 screws per bar. Solved all problems.

Thanks Don. One wonders how they produced them, knowing they vignetted like that...

On the DS-16, there is 3" between the holes, so 1.5" did the trick. I'm hesitant to support the weight of the 16's mirror with just two screws each...

[Bob Myler]

The optional #55 dec control was used on Meade's 6", 8" and 10" reflectors and - at twice the price so I assume it was substantially larger - the #65RS was reserved exclusively for the DS-16. Your tangent arm looks similar to the #55 - but appears much longer (and therefore likely much finer in its adjustments) than mine. Installing or removing it (I have the instructions for the #55) involves removing the declination shaft - and this requires that the optical tube be remove from its cradle + the dec setting circles, counterweights (25 lbs for the THIN one!) and safety collar (toe saver). To reduce friction, two teflon washers were included with the manual system. Like all tangent arms - a simple turn of the knob in either direction will move your scope in declination...

[Bob Myler]

John - PM'd you tonight and I'll e-mail you tomorrow...

[Don Taylor]

My ds10 also vignetted so I moved the primary down by redriing the attach holes for the 3 bars that attach the mirror cell. I ended up drilling midway between the existing holes and only using 2 screws per bar. Solved all problems.

Thanks Don. One wonders how they produced them, knowing they vignetted like that...

On the DS-16, there is 3" between the holes, so 1.5" did the trick. I'm hesitant to support the weight of the 16's mirror with just two screws each...

You could drill and tap matching holes in the aluminum bars to match the odd holes. I used a small template to assure all 3 bars were moved the same amount.

I recall with my ds10 (I'm the original owner) was that ordering the 2" focuser (apparently for ap) resulted in the focuser and secondary being located to produce focus further outside the scope. I have copies of the old Meade/Crownoptics ads here somewhere. I'll try to find some of them.

[precaud]

You could drill and tap matching holes in the aluminum bars to match the odd holes. I used a small template to assure all 3 bars were moved the same amount.

True, and easy enough to do. I'll check it out when I pull the primary... which is so covered in dust that NO reflections can be seen in the autocollimator!

[precaud]

And a set of 500mm cast aluminum rings. The OTA is 19" O.D. As you can see, the previous owner tried to fill the gap with 1/4" plywood covered with suede leather... not a good choice of materials. I have some 1/2" to 5/8" medium-density wool felt that should work much better.

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[precaud]

My ds10 also vignetted so I moved the primary down by redriing the attach holes for the 3 bars that attach the mirror cell. I ended up drilling midway between the existing holes and only using 2 screws per bar. Solved all problems.

I finished re-centering the primary in the cell (previous owner had messed that up) and moved it back 1.1" today. It was supposed to be 1.5" as Don did but the darned tap snapped in the first hole I drilled so I stepped it back a bit and moved on. The 1.1" ended being right on and as you said, it solved all the vignetting problems.

With the secondary centered, it now collimates spot-on. That secondary is definitely a pain to adjust, but after really torquing down the holding screws, it holds collimation even as the OTA is flipped and rotated about. So it's good for now. But at some point a new spider/holder will be in order.

I haven't cleaned the filthy mirrors yet, but I did some daytime viewing of familiar terrestrial targets and I'm very impressed. Big mirrors are like having a V8 under the hood, seemingly effortless, stable power. I like it.

[jrgose]

John, I've enjoyed my DS-10 for several years. Just learned how to Barlow Collimate (Howie Gladder maker) which is "Aces". I can email you copy of my DS-10 owners manual.
Jeff

[youngamateur42]

I always wanted one of these Meade GEMs

[rolo]

Pretty nice scope, I had the white Starfinder model and it had decent optics. It had a nice set of huge rotating rings that made it a pleasure to use. I do recall the secondary spider was like tuning fork...if knocked, it would vibrate for ever!

[precaud]

Jeff, what's that in your avatar?!?! Looks great! I hope you're enjoying it. Thanks for offering to send the manual, I have it (and several others). If your DS10 manual doesn't cover the AC drive, that detail is in the Starfinder EQ manual.

The scope has been operational for a couple months. I only had a couple weeks to observe and test before our monsoon season arrived, and it has largely sat unused since then. Mechanically everything is in order now and works well, except the AC drive doesn't grab when it is pointed into some parts of the sky.

From what I've read, the primary mirror on this one is pretty typical of other DS's (meaning OK but not great) and I'm making arrangements to have it refigured.

The spider is clunky-looking but actually holds position pretty well, you really have to torque down on all of the bolts holding it in place, though.

All told, even though the rings are working well, I'm not sold on the user interface of a big newt on a GEM - it is cumbersome. I find myself spending a lot of time making ergonomic adjustments which takes away from finding and viewing time. A dob conversion is probably in its future, not till next year, though.

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[tim53]

Give a little thought to building a lightweight truss tube for that puppy before converting it to a Dob.

The 16" with the heavy sonotube is a bit much for that mount, but the mount would be quite suitable for many smaller scopes.

-Tim.

[starman876]

To think at one time in my youth I used to pick up that sonotube by myself and put it on the mount. Note, it was not easy, but I did it. today, they would have to come save me as it was crushing the air out of me as I lay helpless on the ground, on my back, underneath it