Dovetail length ?????

[spaceboy]

Hi All

Just a quick vote on dovetail pros and cons. I have at my disposal a 33cm (large) and 15cm (small) dovetail to use with my C100ED. What are peoples advice on which one to use. The longer in my mind supports the OTA better and reduces strain in the scope itself but the dovetail will itself flex due to it's length. The smaller will be a lot more rigid on the mount but not support the scope as well. The smaller dovetail equals the size of the original clam shell but I use EP's upto 2.2lbs so want to avoid any undue strain on the OTA by having a wider support. I haven't ruled out a medium sized dovetail but was hoping to avoid the extra expense.

Any ideas ??

[Stephen]

I don't mean to be annoying (honest) but get the medium, or saw the large one down

[MjrTom]

I personally usde a 30cm ADM dovetail on my 102mm f/10.

I think at times its a little short and would be better to space the rings slightly further apart as there is more likely to be tube flexure than dovtail flexure.

I have my rings spaced about 30mm from each end of the OTA with a 30mm dovetail to link the rings. This varies slightly depending on where I want the balance point to be.

[spaceboy]

1 vote for medium

1 for long'ish

[spaceboy]

No more suggestions then ???

[glowjet]

You did not say what make of dovetail bar it was ? but I would use the long one as you could consider discarding the clamshell and going for some rings instead, I have the same scope and use a 30cm Williams dovetail plate and solid alloy machined rings mounted into an ADM Losmandy clamp

[Macavity]

Personally, I tend to bolt two bars, of equal (arbitrary) length, but both above AND below the scope. Holes, are typically never quite designed for purpose, but can be drilled out etc. The result is very rigid, and the upper one can then hold anything from a (solar) finder to (doubtless) a complete guide scope system at the BALANCE point!

[George]

Personally I think there's 2 options.

For visual it doesn't really matter as long as the scope is supported properly.

For imaging as far apart as possible would reduce end flex and sag.

As Macavity said, adding another bar across the top ring makes it super rigid and is good for mounting extras.

[spaceboy]

Thanks for the replies guys. I think I'm going to stick with the long one then.

Personally, I tend to bolt two bars, of equal (arbitrary) length, but both above AND below the scope.

Will keep this in mind for the future

[MjrTom]

I have been looking at adding a second dovetail bar to the top of my scope rings, will have to give it a try myself

[rwilkey]

I would say the long one, the more support the better, I use heavy ep's, but the orginal clamshell is fine, if I were to renew I would use the long dovetail.

[glowjet]

Thats a very good point Mjr Tom, it would come in very useful as a carrying handle and to take it to the extreme, if it was a nice stainless circular tube or bar, then one could add a small sliding weight for those delicate balancing issues with eps / cameras etc, or is this taking things to far, just a thought

[MjrTom]

Thats a very good point Mjr Tom, it would come in very useful as a carrying handle and to take it to the extreme, if it was a nice stainless circular tube or bar, then one could add a small sliding weight for those delicate balancing issues with eps / cameras etc, or is this taking things to far, just a thought

No I agree with you although I just use the bottom bar as a carry handle even if its upside down.

For balancing you can use these with a standard dovetail

Baader 1kg Laufgewicht mit Vixen Level Prismenklemme

or something similar

[spaceboy]

That teleskop express do some great accessories just a shame about their postal costs.

[MjrTom]

Hi Nick yeah that's the only problem.

I tend to wait until I have a few things to get then it's less painful.

Most UK retailers don't hold such a variety of stock

I needed a soft case for my 102mm f/10 refractor and the only place I could get it was Teleskop Express no other place stocked Geoptik kit...

[spaceboy]

I needed a soft case for my 102mm f/10 refractor and the only place I could get it was Teleskop Express no other place stocked Geoptik kit...

I was going to say there is one on astroboot that would have probably done you but it appears it has now gone

[MjrTom]

I need to check astroboot a bit more often...