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How is your Questar mounted ?

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215 replies to this topic

#201 Steve C.

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Posted 13 September 2019 - 01:21 PM

No one uses a Gem mount? Why, if so, is that if i may ask?

The fork mount can be set up as equatorial mount. Just set the angle and aim the forks north.

 

The 7" OTA's can of course be mounted on a GEM.



#202 Kevin Barker

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Posted 13 September 2019 - 10:52 PM

So can the 3.5 s with the Duplex. I have used my field( now Duplex) on a gem. Works well. A dovetail can connect using a 1/4 20 screw.
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#203 JMKarian

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Posted 14 September 2019 - 06:16 AM

No one uses a Gem mount? Why, if so, is that if i may ask?

The Questar Astro 7 on a side-by-side with an AP 155 + AP 1100 GEM.  Scopes complement each other nicely in this purely visual setting. 

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#204 Iceni

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Posted 17 September 2019 - 03:31 AM

What size thread does the base of the Q3.5 (50th) take for mounting on a tripod. Apologies for naive question, newbie waiting on Owner Manual, finding ones feet, steep learning curve etc! Notice certain plates offer both 1/4" & 3/8" threaded screws.



#205 Johninuk

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Posted 17 September 2019 - 04:55 AM

It's a 1/4 inch 20 tpi standard tripod thread.

#206 Iceni

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Posted 17 September 2019 - 05:34 AM

It's a 1/4 inch 20 tpi standard tripod thread.

Many thanks. Working blind at the moment without Owners Book etc. Had lovely chat with Jim yesterday so happily sending me over some bits and bobs from HQ



#207 munirocks

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Posted 24 September 2019 - 05:05 AM

The 1/4 inch 20 tpi threaded bolts on most tripod heads, although the correct thread, are WAY TOO SHORT for a Questar for my liking, considering the weight and value of what they will be holding. The thread on a Powerguide II base is also recessed so your average tripod bolt won't even be long enough to reach the threads in the base, much less engage.

 

You're much better off making your own bolt to the right length.  Search the forums for "universal bolt" (using quotes)


Edited by munirocks, 24 September 2019 - 05:23 AM.


#208 munirocks

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Posted 24 September 2019 - 05:27 AM

I use a standard 8-inch equatorial wedge on a very stable and robust B&L astronomical tripod. Because the wedge has a large 4-inch hole in the middle I made an adapter out of some bamboo flooring that I had, as bamboo is very resistant to water and moisture. 

 

attachicon.gif P1130449_lowres.jpg

 

attachicon.gif P1130451_lowres.jpg

 

Note the long center bolt, which has 11 threads available (therefore 11/20ths of an inch) which I made from an endless bolt cut to length. The center hole in the base of my Q is 11.5 threads deep between the start of the threads to the point at which the bolt bottoms out. But the socket is also recessed by about 2.5 threads compared to the flat base, possibly due to the extra base thickness to accommodate the Powerguide II unit. So the socket is in fact 14 threads deep as measured from the base, with the first 2.5 “threads” being made of fresh air. I figured there is no point in meshing only two or three threads when I could spread the stress over 8 threads, so I made the bolt longer than strictly needed, but still 3 threads short of bottoming out. I also extended the bolt length in the other direction under the mount, which makes it four times faster to use - I can quickly spin the bolt into the scope and then use the wingnut to snug up the last 1/8 turn.

 

attachicon.gif P1130450_lowres.jpg

 

Also note the bolt topped by a wingnut on the the lower left on the underside of the mount. That's the fine altitude adjustment bolt - critical for good polar alignment - critical for using setting circles - critical for getting the most out of the Q. 

 

The recessed socket in the Q base raises an important point for tripod users. I don’t think my Q would fit on any of my “standard” photographic tripods as the mounting bolts on them only have about 2.5 threads showing, which is only just enough to span the recess in the base of the Q and no more. Has anyone else noticed this issue? Even if a tripod has a longer-than-usual mounting bolt, I would not trust a mount that only meshes one or two threads. I have seen the threads on bicycle seat post clamps shear off because the bolt was too short and only meshed two threads, although a bike seat post is probably a much higher stress environment than that of a small telescope mount. Maybe this is only an issue for those Qs that have a thicker Powerguide II base unit. It’s not really an issue for me, as I’m now happy with my current mount.

 

Tri-stand fans, how long is your center mounting bolt?

 

Astro-trac fans, how long is your center mounting bolt?

And notice the bolt length in my previous comment.  There is no way I would put a Questar on a standard photo tripod without changing the bolt to a much longer one.


Edited by munirocks, 24 September 2019 - 05:28 AM.


#209 BillHarris

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Posted 24 September 2019 - 10:58 AM

Many hardware stores have a nut&bolt section that has knobs with bolt threads, including 1/4-20. The bolt section is long enough and frequently needs to be shortened.

#210 RMay

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Posted 24 September 2019 - 12:01 PM

I use a Gitzo 501 tripod with either a 301 (smaller) or 501 (larger) pan head. Never had a problem securing it with the standard screw that comes with the head, but I suppose it begs the question... how far can you screw a screw into the base of a Q before it hits something inside?

Ron

#211 Optics Patent

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Posted 24 September 2019 - 02:04 PM

I use a Gitzo 501 tripod with either a 301 (smaller) or 501 (larger) pan head. Never had a problem securing it with the standard screw that comes with the head, but I suppose it begs the question... how far can you screw a screw into the base of a Q before it hits something inside?

The good news is that a long screw will harmlessly abut the steel axle that enters the axial bore from above.  I think there is an inch or more to play with.

 

My cutaway Questar project comes in handy here.

 

DSC 8861
 
As far as strength, knowing a 1/4-20 screw has a shear strength of nearly a ton, a couple threads engagement should hold a 10-pound scope and a 200-pound guy who grabs it in the dark when he stumbles.  Good implicit advice to verify you have enough thread engagement in your setup.  But I've never met a tripod that couldn't adequately engage a Questar, and I recall that the threaded post in the PG-II model protrudes below the rim to avoid the concern of a gap to bridge.  I actually shortened the hub when converting a PG-II back to AC (don't ask).

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#212 RMay

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Posted 24 September 2019 - 04:49 PM

Thanks, Ben... very useful information. 👍👍👍

#213 munirocks

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Posted 25 September 2019 - 05:00 PM

Maybe it was just my sample, but the PG II base on my old Q50th was recessed. None of my tripod bolts would even reach it. It's not the shear strength of the bolt that is the weakest point; it is the aluminum threads in the base which can be stripped of you tighten a bolt hard on only one thread. 



#214 GQuestar

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Posted Yesterday, 07:53 AM

Just picked up a Celestron Nexstar Tripod/Wedge for 4”/5” (93497) from my local camera shop for $125.

Nothing special, but better than tabletop use for now. Very light weight, easy to handle, and pretty stable, but I can see this just being a travel mount.  Not very comfortable to be upon, legs are a little too wide, and mount is a little too low.  Now I understand why I see a few of you using a perch atop the wedge.  That’s what I’m thinking about now in order to raise the overall height and get the eyepiece away from middle of the mount.  Any perch options for purchase, or maybe somebody is just getting tired of the Tristand?!grin.gif

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#215 Optics Patent

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Posted Yesterday, 08:18 AM

Maybe it was just my sample, but the PG II base on my old Q50th was recessed. None of my tripod bolts would even reach it. It's not the shear strength of the bolt that is the weakest point; it is the aluminum threads in the base which can be stripped of you tighten a bolt hard on only one thread. 

It's possible that yours was a conversion upgraded to PGII later, and would have this configuration requiring a long tripod screw.



#216 Gregory Gross

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Posted Yesterday, 01:11 PM

Just picked up a Celestron Nexstar Tripod/Wedge for 4”/5” (93497) from my local camera shop for $125.
Nothing special, but better than tabletop use for now. Very light weight, easy to handle, and pretty stable, but I can see this just being a travel mount.  Not very comfortable to be upon, legs are a little too wide, and mount is a little too low.  Now I understand why I see a few of you using a perch atop the wedge.  That’s what I’m thinking about now in order to raise the overall height and get the eyepiece away from middle of the mount.  Any perch options for purchase, or maybe somebody is just getting tired of the Tristand?!grin.gif

Do you observe standing up? If so and if you find that the height of the eyepiece is too low for you when you're standing, I'd consider getting some kind of height-adjustable stool.

When I started out in the hobby, I stood when I had my eye at the eyepiece. After about nine months of that, I finally built myself a simple three-legged stool out of some scrap wood in my shop. I was amazed how such a simple addition completely transformed my experience at the eyepiece. I found I was able to hold my eye at the eyepiece much more stably because it was easier for me to hold my whole body more stably when seated.

Another benefit of sitting while observing is that you bring the scope down closer to the ground, thereby making the tripod legs shorter and more rigid (less vibration and wobble when they're shorter).

There are lots of stools out there. Search the internet for "height-adjustable astronomy observing stool." Or just use what you may have on hand at home and try it out.


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