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Old 12-08-2020, 07:15 AM
Cliff (Clifford)
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Minitower Pro Solar Tracking Altitude drift?

Hi all,

I have started using the Minitower Pro again as it is just easier to move around than the AZEQ6GT. Working well with the Moon and Planets and even some deepsky with a 80mm Scope, now with my little Coronado Solar Scope tracks fine in Azimuth but seems to drift in elevation , checked everything seems tight so no obvious slippage. I am doing a basic slew to Sun then sync on target.

I am using the extra vixen saddle with a 90deg camera bracket on the weight side no weights on it. I have the Losmandy saddle fitted on the other side.
It is slightly unbalanced but would have thought for such a small scope it wouldn't matter?

Appreciate any ideas-
Cliff
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Old 12-08-2020, 09:20 AM
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Tinderboxsky (Steve)
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Hi Cliff,

I have found my MiniTower Pro to be quite sensitive to imbalance in elevation. If not properly balanced with a scope at 1500mm focal length, I was finding motion in elevation haphazard when trying to centre objects and some annoying drift in elevation. These problems were not so apparent in my other scope with a shorter 580mm focal length.

The solution was to ensure the scope was very close to properly balanced. Note, one needs to have the scope balanced when it is in the horizontal position and in the vertical position. This ensures the scope is properly balanced in any elevation position. It was the lack of good balance in the vertical position that was causing my problems.

Steve.
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Old 12-08-2020, 03:25 PM
Cliff (Clifford)
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Thanks Steve ,
the problem with the Coronado the eyepiece position is fixed so the need for the 90deg camera adapter. For astrophotography it doesn't really matter. Will try to get a better balance it weighs only a few kg but might make a difference. Maybe I'll get a Losmandy to Vixen adapter so I can use the main mounting side without having to change the saddle back again. Or a Losmandy for the Coronado way overkill.

The Coronado is only 400mm , have had my 6"SCT 1540mm on it and that seemed fine as does my 76mm 570mm Tak. But they were both pretty well balanced.

How did you achieve good balance in both vertical and horizontal on the Elevation side ?

Appreciate your help
Cliff
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Old 14-08-2020, 09:10 AM
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Tinderboxsky (Steve)
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Hi Cliff,
I have found that it does not take much off centre weight to cause imbalance issues for longer focal length scopes on these mounts. In my case the standard, relatively light weight finder scope on my 1500mm focal length Skywatcher Mak127 was causing the problem.
I’ll set up the scope this weekend when the weather clears and take some photos to show you how I have balanced everything, especially when the scope is in the vertical position.

Steve.
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Old 22-08-2020, 11:34 AM
Cliff (Clifford)
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Hi Steve,

I think I found the culprit still drifts a little but the shaft on the weight side was not fully tight I had to use multigrips with a piece of heavy rubber to tighten the small collar fully. Now much better .

Now if I can get a 90deg dovetail or something so I can balance it better.

Tried it on the AZEQ6 nearly perfect tracking no surprise not even using counterweights nothing small enough.

Cheers
Clliff
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Old 22-08-2020, 12:34 PM
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Tinderboxsky (Steve)
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Hi Cliff,

Yes, I also use a pair of multigrips to properly tighten that collar. It causes all sorts of havoc if it slips. Get it nice and tight and everything works well.
By coincidence I set my mount up earlier today to show you some photos to explain how I balance everything.

Image 1 shows the general set up. You can see I have mounted a battery on the second dovetail mount. This replaces the normal counterweight and provides the mechanism to balance everything when the scope is vertical.
Image 2 shows the battery cradle and its dovetail bar.
Image 3 - balance the scope in the horizontal position by sliding the scope along the main dovetail clamp. You will notice the battery is centered in this position and has no effect on balance. There is a Mak Cas hiding under the dew shield, hence the balance point is towards the rear of the scope.
Image 4 - balance the scope in the vertical position by sliding the battery cradle in its dovetail clamp. You can see the battery is off set and effectively balancing out the effect of the finder scope hanging off the side of the scope. Image 5 gives a slightly different view of the same position to highlight the finder scope hanging off to one side.

This works really well and is easy to adjust.

If you have your solar scope where I have my battery then you could achieve the same result by clamping a piece of wood with a weight attached at one end onto your Losmandy dovetail.

I hope this makes sense.

Steve.

PS, A slight hiccup, images to come shortly!!
PPS Images in correct orientation now attached!!
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Last edited by Tinderboxsky; 22-08-2020 at 01:03 PM. Reason: Addition of images
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Old 24-08-2020, 07:32 AM
Cliff (Clifford)
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Thanks Steve,

Great ideas on balancing and love the wooden accessories

Definitely will try something like that , I like the quick and easy setup on the Minitower Pro. I see you have a SkiFi how do you find it ?

I use an intel NUC at the scope and remote desktop in on my Mac but a wireless solution you have would be a nice option particularly for visual.

Appreciate your help
Cliff
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Old 24-08-2020, 08:37 AM
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Tinderboxsky (Steve)
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Hi Cliff,

Yes, the MiniTower Pro is a great little mount. Easy to set up and surprisingly accurate if care is taken with levelling at the outset.

Mine is used exclusively for the regular outreach sessions I am involved in. It will often have a Vixen ED103S refractor aboard. Hence the need for the wooden pier riser to avoid hitting the tripod legs.

The SkyFi works a treat. It is fully compatible with the MiniTower Pro and I use it in conjunction with Sky Safari Pro on on all of my Apple devices. The wifi network is robust - I cannot recall a drop out. I am not sure about it’s range.

Being able to ditch the hand controller is liberating!
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