Dovetail and Losmandy Plates - One or the Other?

[skir]

Do all telescopes accept both types of plates? Is there an advantage of one of the other? If so why?

[steppenwolf]

Both are essentially dovetail bars (dovetail is just an adjective describing the profile of the bar). The Two industry standard types of dovetail bar are 'Vixen' and 'Losmandy'.

Vixen is narrower and suitable for smaller, lighter 'scopes especially for observing whereas Losmandy is better suited to larger instruments and for imaging as it is stiffer and unlikely to flex which can be a problem with Vixen style dovetails.

If you have an instrument with tube rings, these should fit either type of dovetail bar.

[skir]

Both are essentially dovetail bars (dovetail is just an adjective describing the profile of the bar). The Two industry standard types of dovetail bar are 'Vixen' and 'Losmandy'.

Vixen is narrower and suitable for smaller, lighter 'scopes especially for observing whereas Losmandy is better suited to larger instruments and for imaging as it is stiffer and unlikely to flex which can be a problem with Vixen style dovetails.

If you have an instrument with tube rings, these should fit either type of dovetail bar.

Its a newt 8" and has tube rings. As I will eventually want to get into ap I guess it will make more sense to fit the losmandy bar?

[Freddie]

Yep, Losmandy is the way to go as you will find the Vixen is a bit "bendy" for AP.

[steppenwolf]

With an 8" Reflector, I'd prefer to use a Losmandy bar - your mount must, of course, support this dovetail type.

[kirkster501]

Congrats on you 9000th post Steve. Great advice too - thinking of a larger reflector myself.

[skir]

With an 8" Reflector, I'd prefer to use a Losmandy bar - your mount must, of course, support this dovetail type.

My mount is a cg-5 so I think I will need a losmandy adapter plate? But I'm not sure about that, if someone could confirm or otherwise that would be great.

[steppenwolf]

My mount is a cg-5 so I think I will need a losmandy adapter plate?

Something to bear in mind is the weight increase that a Losmandy bar and the necessary adapter would add to the mount that you currently have. Losmandy dovetail bars are stiff but heavy in comparison with Vixen bars.

[cantharis]

My mount is a cg-5 so I think I will need a losmandy adapter plate? But I'm not sure about that, if someone could confirm or otherwise that would be great.

I have an adaptor on my EQ5 (same as cg5) that takes Vixen and Losmandy dovetails.

http://www.firstlightoptics.com/celestron-mounts/adm-dual-saddle-upgrade-for-eq5-and-cg5-mounts.html

[Patrice Lanteigne]

I agree with the larger dovetail for heavy scopes. I put one on my AR152 but had to buy an ADM adaptor for my EQ6. The adaptor came with a replacement puck and a longer dual purpose clamp style saddle. This has considerably improved the rigidity of the setup.

ADM is good stuff and well priced for the quality. I've bought a dual saddle for my Duo-T as well. The dual "DV" saddles allow for both wide and narrow dovetails.

I've purchased the products directly from ADM - very reasonable shipping and ultra fast service added to good advice when you need it. Mr. Anthony Davoli is a stand-up guy willing to help and easily reached via e-mail through his "contact" link on his web site.

http://admaccessories.com/default.htm

[cantharis]

ADM is good stuff and well priced for the quality. I've bought a dual saddle for my Duo-T as well. The dual "DV" saddles allow for both wide and narrow dovetails.

Agreed totally - ADM is superb quality gear.

[M4lcs67]

Just coming in on this thread. When I got my C9.25 and CG5 earlier this year, I was very suprised at the way the ota attaches to the mount by just a couple of knurled bolts. (Anyone who has a CG5 will know what I am talking about). To my mind it isn't a very clever way to attach the tube to the mount. (Slide the dovetail into the mounting head then lock it off with the two bolts). Not only does the lovely orange anodised dovetail bar get chewed up by the bolts as all they are doing is gouging into the soft aluminium, but by doing things by this method the weight of the whole ota is supported on these two bolts only and if they do work loose the tube could come away.

Blimey, even my Nexstar 127 SLT has a better way of doing it. It has a sliding bar that attaches to the lockbolt so when you attach the ota to the mount and tighten it the tube is supported the whole length of the bar. Not just some small area. We are talking a very heavy tube with the C9.25 and expecting such a rubbish method of locking it out seems crazy in the extreme. I did query it with FLO when it arrived and they said that it was a safe method and that they hadn't heard of a failure. Still seems a lousy way of doing it when you are spending a large sum of money. Even if they put an extra few quid into it to make the fitting better. Or is that why there are all these aftermarket alternatives????

[steppenwolf]

Congrats on you 9000th post Steve.

9000 sets of drivel, how do I get away with it? :grin:

[x6gas]

My mount is a cg-5 so I think I will need a losmandy adapter plate? But I'm not sure about that, if someone could confirm or otherwise that would be great.

You'll struggle to do AP with an 8" newt on the CG-5. I am a big fan of the CG-5 and often use it for AP, but only with my 90mm refractor. An 8" newt will really be pushing the capabilities of the mount by the time you include the camera(s) etc.

[skir]

You'll struggle to do AP with an 8" newt on the CG-5. I am a big fan of the CG-5 and often use it for AP, but only with my 90mm refractor. An 8" newt will really be pushing the capabilities of the mount by the time you include the camera(s) etc.

yes you're right I think I would be stretching it from more reading. But I've also realised that some very good pictures can be had from a smaller, lighter scope as well. So I guess I will have something more specifically for imaging in the future.

[M4lcs67]

Well, today have bitten the bullet and bought a new saddle for my CG 5 to replace the ghastly Celestron one.

http://www.firstlightoptics.com/dovetail-bars/adm-dual-saddle-upgrade-for-eq5-and-cg5-mounts.html

Not only will it protect the lovely orange anodised dovetail from any further destruction, but the new saddle will spread the weight much better and grip the dovetail along the length of the saddle rather than just the two knurled bolts that Celestron put on. I guess it is a bit of a poor do when someone else has to design, manufacture and market an alternative, because the original manufacturer has a flawed design. Even if Celestron had put the price of the CG 5 up a little to cover the additional cost then that would help matters.

The ADM saddle is pretty expensive, but at least I will be confident that the ota is securely attached in the future.

[skir]

Well, today have bitten the bullet and bought a new saddle for my CG 5 to replace the ghastly Celestron one.

http://www.firstligh...cg5-mounts.html

Not only will it protect the lovely orange anodised dovetail from any further destruction, but the new saddle will spread the weight much better and grip the dovetail along the length of the saddle rather than just the two knurled bolts that Celestron put on. I guess it is a bit of a poor do when someone else has to design, manufacture and market an alternative, because the original manufacturer has a flawed design. Even if Celestron had put the price of the CG 5 up a little to cover the additional cost then that would help matters.

The ADM saddle is pretty expensive, but at least I will be confident that the ota is securely attached in the future.

very nice. How does the part on the right of the picture fit? I'm having difficulty envisaging it.

[M4lcs67]

Hey skir,

I have absolutely no idea. Guess i'll find out when it arrives tomorrow.

[skir]

Hey skir,

I have absolutely no idea. Guess i'll find out when it arrives tomorrow.

ah, ok. Let us know how you get on with it and how it fits.

[MarkSix]

very nice. How does the part on the right of the picture fit? I'm having difficulty envisaging it.

The part on the right is the motor mount/saddle adaptor. You need to open the plastic cover for the dec motor housing and replace the original adaptor.

[M4lcs67]

Thanks MarkSix. It has arrived, but I haven't had a chance to look at it yet. The Fedex bag that it was delivered in feels heavy though.

[skir]

The part on the right is the motor mount/saddle adaptor. You need to open the plastic cover for the dec motor housing and replace the original adaptor.

Thanks. It makes sense now from your description and comparing the pic of the adapter to my mount.

[M4lcs67]

Just installed the new saddle onto my mount last night. Very easy to do (with the right tools). It is a beautifully engineered thing. I can see why it is quite pricey. Looks like they have put a solid piece of aluminium into a CNC lathe, hit the go button then once it has done it's work, out pops the finished piece. Then once anodised and assembled it really is a great looking thing. Judging by how meaty and solid it is, it should perform very well in the field. I'll be giving it a dry run in the house later. Assemble the whole rig and get a feel for it. Hopefully now I won't be worried about the ota detaching itself. And the orange dovetail bar can breathe a sigh of relief now. No more steel bolts gouging at the soft metal of it anymore.

[skir]

It certainly looks a sexy bit of kit, but the price is a little eye-watering. Be interested to know if it makes the mount more stable in use.

[M4lcs67]

Hey skir. You are certainly right about the cost of it. A bit of a killer, but if it makes things better then I think it will be worth it in the end. Sometimes you have just got to bite the bullet. Of course if you don't have the funds then you have to make do. I want to get the best out of my astronomy and I don't do anything else and it is my main hobby now. Luckily I have an understanding wife. I know that the new Starsense camera is out in May/June in the UK and I am seriously considering getting it, but I think I will hold off until it has been out for a while and I can get some opinions from other people as to if it actually works as good as Celestron say it does. The manufacturers seem to big things up sometimes, but in the real world they don't live up to the billing. That's why I think I will hold off. The word is that it is going to be around £300, so I don't want to be making a huge mistake by buying one to then find out that they are not very good. I'll wait for other people to do the beta testing and then if I am happy then I will buy one.