WO Star 71 and ASI1600MM-C with FW... Balancing

[souls33k3r]

Hi guys, 

I wanted to get the attention of user with WO Star 71 and ASI1600MM-C camera and ZWO 8 Pos FW (or any camera which is heavy)  

Now I have a separate thread going on with the correct adapter so wanted to keep this question separate to the other. 

Last night I was out trying to get the first light with the new toy and when I mounted my scope on my NEQ6 mount, the vixen dovetail went up to a certain extent before I the focuser metal start to hit and block it from going any further. 

Now since I couldn't attach my ZWO camera and ZWO FW, i'm a bit worried that I might be able to achieve the correct balance. 

Without the camera and FW, the scope did seem front heavy which was good so hopefully by extending the dew shield I will have a bit more weight ar the front. 

May I ask the owners of heavy gear with the same scope how are you balancing your WO Star 71 scope? Do you use any counterweights?

Many thanks in advance 

[MartinFransson]

Just a thought - do you really need perfect balance with so relatively light equipment on such a beefy mount? 

Maybe you could add a small weight to the front of the scope?

I'm waiting for a 1600mm-cool with The 8-pos wheel myself but I have a different scope.

[Droogie 2001]

I use this counter weight near the front of my OTA. I had issues with balance when I purchased my Moravian CCD. Have to say balancing was something I had not anticipated in being such a problem.

https://www.firstlightoptics.com/counterweights/baader-dovetail-bar-levelling-counterweight.html

In the end I had to mount my Star 71 on top of a dovetail bar as well:

https://www.firstlightoptics.com/dovetail-bars/adm-vixen-type-dovetail-with-wide-top.html

 

 

[ollypenrice]

Without a picture it's hard to visualize exactly where your space runs out, but would it help to rotate the tube till it was the other way up? I've done this when the focus knobs collided with the attachments before I was in balance. The focuser would just be upside down. (This can make the lock screw inaccessible, though.)

An alternative is to put a height-raising spacer between scope and dovetail or, as Martin and Droogie say, a small weight up front.

Olly

[souls33k3r]

5 minutes ago, Droogie 2001 said:

I use this counter weight near the front of my OTA 

https://www.firstlightoptics.com/counterweights/baader-dovetail-bar-levelling-counterweight.html

 

Do you have the same scope and heavy gear at the back? 

3 minutes ago, ollypenrice said:

Without a picture it's hard to visualize exactly where your space runs out, but would it help to rotate the tube till it was the other way up? I've done this when the focus knobs collided with the attachments before I was in balance. The focuser would just be upside down. (This can make the lock screw inaccessible, though.)

An alternative is to put a height-raising space between scope ad dovetail or, as Martin says, a small weight up front.

Olly

Not a bad shout Olly about rotating the tube... Just Google the images of this scope and from the bat I can see people are doing just that with their focusers upside down. I guess everyone has this issue then. 

Basically it's not the focus knob itself but it's the housing at the end of the focuser which is a thin metallic solid strip that ever so slightly touches the Dec axis puck and the doesn't want to move any further. 

Height raising dovetail? I'll look that up too. I do have a long spare vixen dovetail that came with my mount (or was it the scope? Can't remember), I should be able to just attach the WO vixen to the skywatcher vixen and that should give me enough height? Hmmm something I'll test tonight 

[groberts]

With my WO GT81 + ZWO1600MM-Cool I'm successfully using a Losmandy plate and one of these which works very well:

 

https://www.firstlightoptics.com/adm-counterweight-kits/adm-dovetail-counterweight-kit-d-series.html

 

 

 

[Davey-T]

I have mine rotated so that the focuser is upside down and also have a 15mm plate between the dovetail clamp and the mount to get more clearance.

Dave

[souls33k3r]

Just looked into rotating of the scope and found that I won't be able to use the finder shoe that I bought to mount my guidescope

[Davey-T]

I have the finder mounted on a small strip of aluminium bolted to the top of the tube rings.

Dave

[Andyb90]

Also if you haven't already done this its good to extend the drawtube out to the approximate focus point when balancing as that will make the setup more back heavy.

Andy.

[souls33k3r]

all very helpful suggestions everyone. I'll give them all a go and see which one works best.

As always, you lot have been super helpful

Thank you very much

[ollypenrice]

2 hours ago, souls33k3r said:

Just looked into rotating of the scope and found that I won't be able to use the finder shoe that I bought to mount my guidescope

Doh, isn't it always like this??? 

Dave has the answer, I think.

Olly

[souls33k3r]

11 minutes ago, ollypenrice said:

Doh, isn't it always like this??? 

Dave has the answer, I think.

Olly

he does indeed  super helpful guy

[souls33k3r]

Just thought of a question, i have mainly been imaging using Celestron EdgeHD so once you balance the scope, everything stays there but with WO Star 71 how do you balance the scope initially? with the focuser drawn out completely or while it is at zero (whatever that position is called when the focuser is all the way in)? Surely the balance will change every so slightly (but enough) to tip the scope out of balance?

[Anne S]

When I bought my WO ZS80ii I also bought a WO Vixen dovetail. They are much higher than the norm. Very solid too and come in different lengths. They will need rings too. That may raise the focused enough.

Anne

[souls33k3r]

1 minute ago, Anne S said:

When I bought my WO ZS80ii I also bought a WO Vixen dovetail. They are much higher than the norm. Very solid too and come in different lengths. They will need rings too. That may raise the focused enough.

Anne

Thanks for the reply Anne. 

So what you're saying is that i will have to ditch the rings that came with the scope and buy the new ones?

[Anne S]

27 minutes ago, souls33k3r said:

Thanks for the reply Anne. 

So what you're saying is that i will have to ditch the rings that came with the scope and buy the new ones?

No, just the dovetail part. The rings should attach to the new plate. I have noticed though that WO sell scopes with matching rings! It's just a suggestion. It would be cheaper to rotate the focuser. I have to do that with my Altair Wave 102 to get balance.

[souls33k3r]

Just now, Anne S said:

No, just the dovetail part. The rings should attach to the new plate. I have noticed though that WO sell scopes with matching rings! It's just a suggestion. It would be cheaper to rotate the focuser. I have to do that with my Altair Wave 102 to get balance.

ah ok, going to work on that tonight at some point and see how it goes. 

My other question was regarding balancing of the scope with these refractors, how do you balance the scope initially? with the focuser drawn completely out or completely in? because once you start playing with the focuser to get the proper focus at night, the whole balance shift happens won't it?

[souls33k3r]

8 hours ago, Davey-T said:

I have mine rotated so that the focuser is upside down and also have a 15mm plate between the dovetail clamp and the mount to get more clearance.

Dave

Dave, would you have any pictures of what your setup looks like?

Also, when you rotate the scope, do you just turn it upside down or you un-thread the clamp screws and just rotate the OTA and then thread the clamp screws back?

Will be leaving for home in a few minutes so wanted to be best prepared with all the knowledge to do it properly

Thanks in advance

[Davey-T]

Sorry for the delay in answering had to go to a funeral, I just rotate the scope in the tube rings, I've got mine set up as side by side now so a bit different to yours.

Dave

 

[sloz1664]

I balanced my WO 71Star & AA80 Triplet set-up by adding my 200mm wide field kit atop of the WO Star and an additional weight on the front of the losmandy plate.

Steve

[Andyb90]

5 hours ago, souls33k3r said:

My other question was regarding balancing of the scope with these refractors, how do you balance the scope initially? with the focuser drawn completely out or completely in? because once you start playing with the focuser to get the proper focus at night, the whole balance shift happens won't it?

Once you've focused for the first time you can record the drawtube position from the scale on it. Then you can rack the focuser out to that position for balancing. Should be fine then.

Andy.

[souls33k3r]

2 hours ago, Davey-T said:

Sorry for the delay in answering had to go to a funeral, I just rotate the scope in the tube rings, I've got mine set up as side by side now so a bit different to yours.

Dave

 

No need to be sorry mate, thanks for sharing your setup image with us. This is really helpful in understanding what to expect. 

 

1 hour ago, sloz1664 said:

I balanced my WO 71Star & AA80 Triplet set-up by adding my 200mm wide field kit atop of the WO Star and an additional weight on the front of the losmandy plate.

Steve

Interesting counterweight. Might I ask what exactly it is and how is it attached to the plate? 

46 minutes ago, Andyb90 said:

Once you've focused for the first time you can record the drawtube position from the scale on it. Then you can rack the focuser out to that position for balancing. Should be fine then.

Andy.

Cheers Andy for confirming that. But then that means that I will have to roughly balance the scope and then fine focus it on an object when it's dark, mark the position and then rebalance the scope again? Also wouldn't the focus change throughout the night so will the scope not go put of balance? I know it's going to be minor adjustments (hopefully) but that should be ok yeah? 

[sloz1664]

53 minutes ago, souls33k3r said:

Interesting counterweight. Might I ask what exactly it is and how is it attached to the plate? 

1 hour ago, Andyb90 said:

 

I drilled & tapped the end of the losmandy plate and manufactured the weight so it can screw int the plate and is held securely in place with a lock nut. I can fine tune the balance by screwing the weight in or out.

 

Steve

[ollypenrice]

Focus and balance: if you can get to image a terrestrial target about a mile away or more, that will be close enough to your astronomical focus to allow you to balance. If you have too much light by day, try the Ha filter. I can get a rough focus on a distant ridge.

Olly

PS Alternatively someone on here using the same scope and camera might be able to tell you how much draw tube they have extended. Anything to save precisous sky time.