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Your advice please.... moving c8 Ultima ot to a nexstar mount?

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#1 petersmeadelx6

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Posted 30 November 2018 - 08:48 AM

So, I have a nice c8 Ultima with double encoders and the control box-display. Nice for its time. I find this all a bit heavy for my weakened shoulder (long story) and wondering if I should replace this with a newer c8 nexstar model. 

On one hand, I like the sturdiness of the Ultima mount. 

I also read mixed reviews about the Nexstar 8 mount.

I figure it might be more economical for me to find a used mount and sell off my fork arms and tripod (no brace) and keep my wedge (if the wedge is adaptable to the c8 tripod) then sell this all off and look for a complete unit.

Then again, I have seen complete, used nexstar 8 units for around $900 (cdn) but not sure what I would get for the Ultima and encoder package (I do not want to part it out).

I would keep my 2" diagonal and eyepieces ) televue 2 and 1.25 assortment) as there is no issue with the visual back.

 

Can the OTA from the Ultima be safely mounted to the Nexstar 8 mount or do I require some hard-to-find bracket?

 

If any of you have had both mounts, how would you compare for general viewing and photography?

 

Thanks

 

Peter B.



#2 Jeff Struve

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Posted 30 November 2018 - 09:40 AM

Since you mention AP, have you thought about getting rid of the tripod, fork mount, and wedge and putting radius blocks and a dovetail on the C8 for use on an EQ mount?



#3 kellyvictoria

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Posted 30 November 2018 - 10:31 AM

I am not as experienced as others, but initially I thought "oh this Nexstar C8 will be a grab & go to dark sites" which it is. It is also used on my back patio at home. However I have found that I want to do more with it. Like attach a 60mm scope on top or a DLSR on top. But with 2" eyepieces and diagonal I just don't trust the integrity of the mount to hold the weight with anything additional. Or that Bevel which holds the tube. Or the strength of the motors to be accurate w/GoTo.

 

So granted without the above mentioned additionals and with just a finder scope & telrad on it, there is another problem of ….there is no reasonable place for the Talent Cell battery or Kendrick Dew Remover. I have the Talent Cell tightly Velcro ed to the mount arm and the Kendrick Velcro-ed to the tube itself.

I often think it would be great to have a somewhat light weight fork arms replacing the single arm Nexstar on it.

 

I feel it is limited at dark sites with just the essentials on it. But then again what Grab n Go isn't.

 

Now on the other hand... On the bottom of my fork mounted C11 there are 5" wheels attached to 40"x3 1/2" & 47x3 1/2" x 1/2" thick wooden (I think they are Birch) dovetailed crossed supports.

 

If my Nexstar C8" were my primary scope without fork arms I would be in trouble. If it had fork arms I would probably put wheels underneath it.  

Just my experience, hope this helps...

vk


Edited by kellyvictoria, 30 November 2018 - 02:31 PM.


#4 jallbery

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Posted 30 November 2018 - 10:35 AM

The bolt spacing on the 6/8SE mount is the same as on the Ultima's drive base, and the required bolts are the same diameter and thread.   The problem you may run into is that the 6/8SE mount is wider, and may have clearance issues with the wedge.   I've tried the 4/5SE mount on my Classic 8 wedge (same era as the Ultima), and at my latitude, it worked, but just barely.  It's an issue that should be able to be addressed with spacers or a disk or two of plywood.   You need to be careful that you don't use bolts that are too long and risk damaging the drive.

 

If you have the skills and equipment to cut out plywood disks, however,  I'd eliminate the wedge and create an adapter  to allow you to use the 6/8SE mount in alt-az mode. 

 

Better yet, get an Evo.  It's simply better at everything.  The 8SE mount is really at its limits with a 12-13-pound OTA.  

 

You can occasionally find a used Evo mount for sale.   Or buy the Evo 6 and sell the OTA.

 

I bought an Evo 6, but primarily use it with a 1980 orange tube:

EvoC8OT
 
I used the Farpoint vixen dovetail.  They have a kit that includes the necessary "radius blocks" (actually, more like spacers than what I would call radius blocks), and works well, but you may need to go to the hardware store to get different screws and/or some washers to make things fit to your particular scope (I assume the provided screws work for some 8" Celestron OTA over the years, but only some of the screws were correct for mine).  The ADM dovetail kit is of higher quality, but more than double the price.  The Farpoint is solid and affordable, and a bargain if you don't mind the hassle of getting the right screws.
 
 
Used DSCs don't seem to bring much these days.   The Ultima forks and wedge might get you $200-ish.

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#5 kellyvictoria

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Posted 30 November 2018 - 10:56 AM

Yes, the Evo … there is your ticket...

vk



#6 petersmeadelx6

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Posted 30 November 2018 - 12:57 PM

That ticket is getting expensive!

So, consensus is that the nexstar single arm may be underweight for the 8 sct with peripherals (2 inch finder, eyepieces, 8x50 finder).

Maybe I should put the $$$ into some extra physiotherapy for my shoulder.

 

I also have a "new" etx 125 that I have been waiting to try out (lousy night skies for over 3 weeks now) and a nexstar 5 to compare it to. May just settle for one of those as a primary and the c8 for special occasions.

 

Thanks for the input.



#7 kellyvictoria

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Posted 30 November 2018 - 02:10 PM

It is not underweight for the 2" diagonal, eyepieces & finder. It is actually quite nice and works well with these.

Additionally a DSLR would be fine at the eyepiece end weight wise.

 

I am very pleased with my Nexstar... so much so that I have three … of various sizes … but if I could do it over... I would keep the Nexstar C11" GPS, (which has forked arms), sell the Nexstar 8 mount and 5 mount and go with the Evo. mount.  

but that is just me... I am sure others have more sage advise that would shed light on a variety of options for you to think about … 

vk

 

Edit: I see that my previous post may have led you to believe that it could not handle 2" diagonals etc. Sorry about that... I have changed and tried to be clearer on my above post... 


Edited by kellyvictoria, 30 November 2018 - 03:05 PM.


#8 jallbery

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Posted 30 November 2018 - 03:48 PM

Celestron rates the 6/8SE mount for 12 pounds (see https://www.celestro...load-capacities ).   The Evo is rated for 25...

 

A 8SE OTA weighs in right at the 12 pound limit..  Replace the lightweight finder with a 50mm finder (rather than the stock red dot) and you've added a pound, perhaps more.  Replace the 1.25" visual back and diagonal with a 2" SCT diagonal and you've added another pound.   Stick in a 2" eyepiece and you are looking at 15-16 pounds.

 

Will the 8SE work under this load?  Sure.   Will it be solid enough?  That depends on what you consider acceptable.  I'm happy with my 4/5SE mount (which Celestron rates at 10 pounds capacity) with a C5 (little over 5 pounds) but not a 127mm Mak (almost 8 pounds).   

 

To me, the SE shines at two things:  it's a heck of a lot of telescope for the money (particularly on sale!), and it's a heck of a lot of performance for something that weighs in at 30-35 pounds completely set up.  If you are willing to sacrifice stability for portability, it's the one to pick.   I just think the mount and tripod are better matched to the C6.  And I'm guessing that someone who is used to the beefy double tine fork of the Ultima 8, you might find the 8SE lacking in stability.  But I could be wrong, there.

 

I'm very happy with Evo.  Plus it has an internal battery.  The tripod is lightweight (compared to the Ultima 8 tripod), but surprisingly sturdy.  

 

If you don't mind using a GEM mount. the AVX is very nice for visual work with a C8.



#9 K4PDM

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Posted 03 December 2018 - 08:02 AM

I'm using the standard 8SE mount with StarSense and when I add the 24mm 68 degree ES eyepiece with the 2X ES focal extender it becomes awfully jiggly.

 

And these are 1.5 inch eyepieces, not 2 inch.

 

I feel that I need an Evo mount with my setup, if that tells you anything, but what I have does "work."



#10 mclewis1

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Posted 03 December 2018 - 09:46 AM

I wouldn't consider using a wedge with an 8SE setup, it can be made to work but the mount isn't really appropriate for accurate tracking with a longer focal length scope like the C8 so it's a bit of a waste for imaging. If Kelly is really only interested in visual then keeping an SE in it's alt az orientation is the way to go. If imaging is really the desire then as mentioned a few times upgrading to a gem style mount is probably a better way to go.

 

The in between idea of using the Evolution mount is a good one if visual or simple imaging is all that's desired (short exposure work and EAA style observing/capturing with a nice fast camera setup).

 

The C8 on an SE mount/tripod is indeed at the limits but there is a nice upgrade that is already almost in place. Using the existing Ultima tripod under an 8SE mount is a really nice upgrade (all you need to do is get the appropriate length mounting bolts - they are 3/8" x 16 bolts but you have to watch the length of the threads with the SE mount as you can contact the gears inside if they are too long ... the solution is often just as simple as adding a few washers). It makes the whole package more stable and less vibration prone. This setup is also better without the wedge in place.

 

The Ultima C8 OTA can be de forked from the arms and a simple Vixen/CG-5 compatible dovetail bar added so the OTA can be easily mounted on an SE, Evolution or one of the smaller gem style mounts (they all the same type of saddle to hold the OTA). When purchasing a new dovetail bar it would be good to mention that the OTA is from an Ultima and to measure the distance between the front and rear mounting bolts. Those bolts are the ones with slightly raised heads (slightly domed) and there a number of them on the Ultima OTAs (they are usually used for mounting various accessories but are also appropriate for mounting the OTA). The bolts that are flat and flush with the surface of the front and rear cells are there to attach the cells to the tube in the middle and should not be touched.

 

The orange Celestron dovetail bar used on the SE and other mounts might fit the Ultima OTA without any modifications (the question is about the mounting bolts being in the right place for that OTA) but it might also be good to look at a product from someone like ADM Accessories who's solid bar is a bit more expensive but has more flexibility in how it's mounted.

 

So to recap ...

 

1) it's easy to remove the OTA from the forks and put a Vixen/CG-5 compatible dovetail on it. This will open up many different options.

2) the least expensive and primarily visual only setup is to use an 6/8SE mount, and with the Ultima tripod if you want a more stable setup than with the stock SE tripod.

3) an Evolution mount is a nice upgrade from the SE mount (smoother, more stable, carries a bit more weight) but more expensive (the Ultima tripod will work well under this setup too).

4) if more serious imaging is a desire then going directly to a gem like the AVX mount would likely be the most appropriate. But with the AVX you lose some of the easy of use of the SE/Evolution Alt Az mounts for visual work.



#11 jallbery

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Posted 03 December 2018 - 11:49 AM

 

The C8 on an SE mount/tripod is indeed at the limits but there is a nice upgrade that is already almost in place. Using the existing Ultima tripod under an 8SE mount is a really nice upgrade (all you need to do is get the appropriate length mounting bolts - they are 3/8" x 16 bolts but you have to watch the length of the threads with the SE mount as you can contact the gears inside if they are too long ... the solution is often just as simple as adding a few washers). It makes the whole package more stable and less vibration prone. This setup is also better without the wedge in place.

 

 

I don't have an UItima 8,  but I do have a Classic 8 from the same era.   I don't think that you can attach an 8SE directly to a pre-goto Celestron tripod without either an adapter or modifying the tripod.   My 1991 Celestron tripod has 6 threaded 5/16"-18 holes.  These receive the three bolts that secure the wedge to the tripod (they have double the holes you need so you can choose how the legs are positioned relative to the wedge).  The holes are not big enough for the necessary 3/8" bolts.   Perhaps three of the holes could be bored out, but I don't know if there is clearance for the bolts.

 

The Nexstar GPS 8 and 11 tripods have the holes necessary to accommodate the 3/8" bolts, though.

 

I'm pretty sure that all pre-goto Celestron C8 tripods have the same 5/16" theaded holes, although I think the original locked triangle tripod only has three holes.  Any way, that it why I earlier posted the following...

 

 

The bolt spacing on the 6/8SE mount is the same as on the Ultima's drive base, and the required bolts are the same diameter and thread.   The problem you may run into is that the 6/8SE mount is wider, and may have clearance issues with the wedge.   I've tried the 4/5SE mount on my Classic 8 wedge (same era as the Ultima), and at my latitude, it worked, but just barely.  It's an issue that should be able to be addressed with spacers or a disk or two of plywood.   You need to be careful that you don't use bolts that are too long and risk damaging the drive.

 

If you have the skills and equipment to cut out plywood disks, however,  I'd eliminate the wedge and create an adapter  to allow you to use the 6/8SE mount in alt-az mode. 

 

 



#12 rmollise

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Posted 03 December 2018 - 05:04 PM

So, I have a nice c8 Ultima with double encoders and the control box-display. Nice for its time. I find this all a bit heavy for my weakened shoulder (long story) and wondering if I should replace this with a newer c8 nexstar model. 

On one hand, I like the sturdiness of the Ultima mount. 

I also read mixed reviews about the Nexstar 8 mount.

I figure it might be more economical for me to find a used mount and sell off my fork arms and tripod (no brace) and keep my wedge (if the wedge is adaptable to the c8 tripod) then sell this all off and look for a complete unit.

Then again, I have seen complete, used nexstar 8 units for around $900 (cdn) but not sure what I would get for the Ultima and encoder package (I do not want to part it out).

I would keep my 2" diagonal and eyepieces ) televue 2 and 1.25 assortment) as there is no issue with the visual back.

 

Can the OTA from the Ultima be safely mounted to the Nexstar 8 mount or do I require some hard-to-find bracket?

 

If any of you have had both mounts, how would you compare for general viewing and photography?

 

Thanks

 

Peter B.

 

As you've been told, the scope will be fine on the mount. You can do it. But do you really want to?

 

Photography?  This is not the mount for that. The minimum is probably an AVX GEM. 


Edited by rmollise, 03 December 2018 - 05:05 PM.


#13 mclewis1

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Posted 05 December 2018 - 11:01 AM

I don't have an UItima 8,  but I do have a Classic 8 from the same era.   I don't think that you can attach an 8SE directly to a pre-goto Celestron tripod without either an adapter or modifying the tripod.   My 1991 Celestron tripod has 6 threaded 5/16"-18 holes.  These receive the three bolts that secure the wedge to the tripod (they have double the holes you need so you can choose how the legs are positioned relative to the wedge).  The holes are not big enough for the necessary 3/8" bolts.   Perhaps three of the holes could be bored out, but I don't know if there is clearance for the bolts.

 

The Nexstar GPS 8 and 11 tripods have the holes necessary to accommodate the 3/8" bolts, though.

 

I'm pretty sure that all pre-goto Celestron C8 tripods have the same 5/16" theaded holes, although I think the original locked triangle tripod only has three holes.  Any way, that it why I earlier posted the following...

The two Ultima tripods I've seen had the slightly larger holes for the 3/8" bolts. It's been a long time but I don't believe the owners had modified them. I wonder if Celestron made changes during the production runs of the Ultimas (for the larger C11 Ultima) or from the Classic 8 era into the Ultima's time frame?

 

If a tripod head didn't have those 3/8" bolt holes then it would be trivial to enlarge them with a hand held drill. 

 

It's a good point about the wider base of the 6/8 SE mount and the possible interference with the wedge. I've never liked how the wedge to mount base connections were made, it always struck me as needlessly difficult and risking to mount a heavy scope onto the angled wedge in the dark - especially for those of us at higher latitudes (due to the higher angle of the wedge). 



#14 jallbery

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Posted 05 December 2018 - 12:02 PM

The two Ultima tripods I've seen had the slightly larger holes for the 3/8" bolts. It's been a long time but I don't believe the owners had modified them. I wonder if Celestron made changes during the production runs of the Ultimas (for the larger C11 Ultima) or from the Classic 8 era into the Ultima's time frame?

 

If a tripod head didn't have those 3/8" bolt holes then it would be trivial to enlarge them with a hand held drill. 

 

It's a good point about the wider base of the 6/8 SE mount and the possible interference with the wedge. I've never liked how the wedge to mount base connections were made, it always struck me as needlessly difficult and risking to mount a heavy scope onto the angled wedge in the dark - especially for those of us at higher latitudes (due to the higher angle of the wedge). 

It's likely that my memory is faulty, then.  My Classic 8 wedge has been residing on a Meade field tripod for the last decade or more.  The Classic 8 tripod (with its cracked leg bracket) is in the attic of the garage.  Maybe one of these days I can dig it out to check.  The Meade tripod definitely has the double set of 5/16" threaded holes, and perhaps that has clouded my recollections of the Classic 8 tripod.   However, I believe you'd definitely need a different set of bolts-- At least I can't see how the knobs on the bolts for the Classic 8's drive base would have the required clearance.

 

At any rate, I checked for c8 tripod images with google, and the Ultima 8 tripods that gave me a clear view of the tripod top all had set of 3 5/16" threaded holes, as well as three larger holes, so at least some (and probably all) Ultima 8 tripods would work without modification.  It also looks like the earlier black-tube era tripods had the same arrangement.  I did not find a photo of the Classic 8 tripod, but it likely used the same head as the Ultima (the initial production of the Ultima 8 preceded the Classic 8, and the Ultima 8 line lasted beyond the end of Classic 8 production).  At least some orange-tube C8 era tripods have on a single set of 3 5/16" threaded holes.   One photo I found showed the larger unthreaded holes on an orange-tube era tripod, so perhaps Celestron eventually added the 3 large holes for the convenience of anyone wanting to use a C8 terrestrially, or for those folks living at the north polewink.gif

 

So thanks for replying, and sorry to everyone else if I muddied the waters.  It is now my suspicion that all C8 tripods in the black tube era probably have 3 large holes in addition to the 5/16" threaded holes for attaching the wedge.

 

Hmm---  I recently picked up a cheap 8SE mount that is currently without a suitable tripod.  Maybe that old Classic 8 tripod (and some JB Weld to try and fix the leg) could be a solution....


Edited by jallbery, 05 December 2018 - 12:11 PM.

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