10 replies to this topic

[mountain monk]

How do you balance your C8 on a alt/azi mount, in particular, my SV M002C? Suggestions? I have a 13” Losmandy plate on it. Thanks.

 

Dark skies.

 

Jack

[rmollise]

How do you balance your C8 on a alt/azi mount, in particular, my SV M002C? Suggestions? I have a 13” Losmandy plate on it. Thanks.

 

Dark skies.

 

Jack

 

It depends, of course on what you've got on the rear cell, but usually the dew shield gets it close enough. You can find various commercial solutions. 

 

Including at one of my long-time fave dealers, Scopestuff:

 

https://www.scopestu...om/ss_mrail.htm

Edited by rmollise, 05 August 2024 - 06:00 PM.

[mountain monk]

Thanks, Rod!

 

Dark skies.

 

Jack

[Oldfracguy]

How do you balance your C8 on a alt/azi mount, in particular, my SV M002C? Suggestions? I have a 13” Losmandy plate on it. Thanks.

 

Dark skies.

 

Jack

I had an M002C, and you really have to pay close attention to getting the fore and aft balance set as closely as you can.  I discovered that if you bias a little toward the front end, where when the OTA is horizontal the front (corrector) end wants to drop under its own weight just a tad, then the scope balances better when it is pointed upward at a high angle during use.

 

Here is an even larger and heavier scope than a C8 I had on my M002C.  It's an Orion 8" Classical Cassegrain with a full-length Losmandy rail:

 

 

I had to move the scope almost all the way forward, with only a little travel left on the Losmandy rail in the saddle, so that it would balance:

 

[Echolight]

 I move it a little bit this way, then a little bit that way, until it's balanced 

[mountain monk]

Mine is never balanced. Even if placed at the back end of the 4” plate. To hold it in position I must crank down the knob with a wrench—my old arthritic hands won’t do it. I have no problem with my NP-101, so it’s not the mount. The C8 can be balanced on my DM-6 on my Planet, but IMHO that’s ridiculously over mounted.

 

Dark skies.

 

Jack

[Oldfracguy]

Mine is never balanced. Even if placed at the back end of the 4” plate. To hold it in position I must crank down the knob with a wrench—my old arthritic hands won’t do it. I have no problem with my NP-101, so it’s not the mount. The C8 can be balanced on my DM-6 on my Planet, but IMHO that’s ridiculously over mounted.

 

Dark skies.

 

Jack

That does not surprise me.  It seems to me, based on my experiece with these friction-type "push-to" mounts (Stellarvue M002C and Supermount W-Standard), that they work best with longer OTAs that have roughly the same amount of weight at both ends, as refractors do.  Right now I have a 150mm Mak that weighs about the same as a C8.  It is really a pain to use on the W-Standard, especially when looking up at a high angle with a 2" diagonal and 2" eyepieces.  I can't move the scope forward enough to balance, and have to crank down hard on the Altitude tension knob so the scope won't fall backward.  Then, the movement is so tight that it's difficult, if not impossible, to track a target.

 

For one of these catadioptric scopes like a 4"-6" Mak or a C5-C8 SCT, I prefer to use the old CG-4 converted to Alt-Az mode.  It never gives me any trouble:

 

[mountain monk]

Yep, that’s my problem. And my heavier eps—my 31 mm Nagler—make things much worse, so now I’m using a 32 mm Matsuyama 85* for sweeping, it’s even lighter than the 30 mm UFF. I also found the Supermount Mini-s to have problems with balance. 
 

Dark skies.

 

Jack

[Chris Johnson]

Load the scope with your diagonal, eyepiece, finder and dew shield. Then balance it on a dowel or drill bit and center mark the dovetail. 

[Echolight]

Yep, that’s my problem. And my heavier eps—my 31 mm Nagler—make things much worse, so now I’m using a 32 mm Matsuyama 85* for sweeping, it’s even lighter than the 30 mm UFF. I also found the Supermount Mini-s to have problems with balance. 
 

Dark skies.

 

Jack

That must be the deal. All the eyepieces that I use with the C8 range in weight between 20 and 28 ounces.

 

Even when I remove an eyepiece, the scope stays put.

 

I'm using a fairly big but not too big Unistar mount.

Shown with the 28 ounce 28 PWA. I wish it was a 24 ounce 28 UWA 

Edited by Echolight, 10 August 2024 - 12:38 PM.

[whizbang]

My C8 bogs down both of my manual alt az mounts.

 

What I do is use a .63 reducer corrector and 1-1/4 inch eyepieces to reduce the payload on the mounts and allow them to operate smoothly.