ST80 Mounting

[Richard N]

I have a Meade Adventure Scope 80 (ST80) which has a short dovetail fitted. I now have an AZ5 mount. I want the scope to be balanced (I'm using a better diagonal and eypieces which are a lot heavier than the ones supplied). It seems to work as it is on the AZ5 but if I want to take some phone-camera pictures the balance will be severely out, also like this the scope is mounted sideways (focusser runs up and down instead of left right) and the red dot finder is almost impossible to use (no big loss).

I could:

1. use it as it is

2. fit a longer dovetail - solves the balance problem perhaps but scope still sideways

3 buy scope rings and a longer dovetail - more expensive.

I would welcome suggestions. Thanks.

Edited August 7, 2021 by Richard N

[Pixies]

Mine (Skywatcher Strartravel 80) has rings and a longer dovetail - but hat's how it came secondhand.

It's a great pairing with an AZ5.

 

[Tiny Clanger]

24 minutes ago, Richard N said:

I have a Meade Adventure Scope 80 (ST80) which has a short dovetail fitted. I now have an AZ5 mount. I want the scope to be balanced (I'm using a better diagonal and eypieces which are a lot heavier than the ones supplied). It seems to work as it is on the AZ5 but if I want to take some phone-camera pictures the balance will be severely out, also like this the scope is mounted sideways (focusser runs up and down instead of left right) and the red dot finder is almost impossible to use (no big loss).

I could:

1. use it as it is

2. fit a longer dovetail - solves the balance problem perhaps but scope still sideways

3 buy scope rings and a longer dovetail - more expensive.

I would welcome suggestions. Thanks.

4 get something like this

https://www.teleskop-express.de/shop/product_info.php/info/p10777_TS-Optics-Adapter-Plate-for-alt-azimuth-Mounts-with-perfect-Weight-Compensation.html

- even more expensive ! (about £75)

Not sure if the geometry would work with an az5, but I'd rather like one to put the st80 or binos on my TS AZ6 . There may well be cheaper alternatives of this kind of thing available, that is just one I came across as a suggested extra by that retailer.

There is a skywatcher L bracket for around £30, https://www.firstlightoptics.com/celestron-mounts/skywatcher-l-bracket-dovetail.html  but that has a dovetail to the AZ5, and a standard camera screw to the instrument, so you'd need an adaptor for photo tripod screw to dovetail clamp (Baader do one for about £30 https://www.firstlightoptics.com/dovetails-saddles-clamps/baader-vixen-style-dovetail-clamp.html  ) . Altho' maybe your ST80 has some tripod thread holes drilled in the dovetail ? Some do, but even if so, it might not be at a good balance point, and it feels a bit precarious when I tried it.

I use my st80 on a photo tripod head, with one of the Baader dovetail clamps, with the tripod head tipped over to the side to lower the centre of gravity, so I understand what you mean about the sideways focus control ... I just put up with it !

Heather

 

[StevieDvd]

Because the ST80 is focuser-end heavy, especially when loaded, and has such a short tube to attach to it's difficult to balance in the clamp.  A longer dovetail will give you a little more adjustment, but as you have discovered it will be limited by the orientation of the focuser. Adding dfferent scope rings will have the same limitations.

You could try a longer dovetail and see if you can add some weight to it, on the opposite end to the focuser, to help.

Option 4 mentioned by Tiny Clanger replaces the balance method and would work, as you are balancing the entire scope against a set of weights instead on the scope itself. It would also let you have the focuser controls as you'd like.

[Alan64]

3...

That's my Antares 805, an 80mm f/6 achromat, and only 80mm longer than an ST80.  I think that that's a 13"/33cm bar.

Edited August 9, 2021 by Alan64

[StevieDvd]

If the balance is almost there you could move the rear scope ring closer to the front one, before spending on anything.

[Richard N]

Okay so what did I do? I reviewed the options above first. Some seemed rather "over engineered" while others added a lot of bulk. Some seemed to have the possibility of adding "wobble". After much searching I found a "nearly" suitable 120mm dovetail. This did require the mounting holes to be drilled out (easy) and works a treat. I also discovered that the dew shield is easily removed and parallel so I was able to turn it round and rotate it such that the telescope branding looks "right" - perfectionist at work. It all works well and looks right so I'm good to go. Thanks for the suggestions - they were useful in helping me decide what was the best option for me. It does not solve the red dot problem but I have found that a finder is unnecessary on such a wide field scope.

https://www.ebay.co.uk/itm/272814342158

Edited August 10, 2021 by Richard N