ADM vs Losmandy
Posted 09 March 2009 - 12:28 PM
The vixen style just uses one screw on each end to mount the dove tail to the ota,rather than the blocks shown in the photo above..
You'll need the vixen version.
Posted 09 March 2009 - 01:33 PM
Isn't there a way to attache the vixen-style dovetail (I have both the 8" and the 13" one - from Orion) to the Losmandy dovetail?
Also - doesn't the Atlas comes with vixen-style head?
Posted 09 March 2009 - 02:23 PM
Vixen compatible dovetail rails are 1.75" in width. Losmandy D type plates are ~4" wide (the actual dovetail is 3" wide at its narrowest point). Careful with the nomenclature as Losmandy also makes a V or Vixen compatible rail as well.
Either the Vixen dovetail rail or the Losmandy D type plates should IMHO be on some form of "base". This can take the form of small radius blocks at each end of the rail/plate or a full length plate that the dovetail rail bolts onto (see Scopestuff http://www.scopestuff.com/ss_mpc8.htm for a picture and better explanation).
The exception to the idea of using separate blocks or plates is the Celestron CGE rail ... it is a Losmandy D compatible rail that because of it's unique shape can be bolted directly to the OTA.
Ido, I'm with you ... I'd never want my scope held to the dovetail rail by only two bolts unless it was sitting on a flat surface (like that provided by the radius blocks or full length plate). When a dovetail rail is bolted down to the blocks it can make use of a much heavier bolt.
Posted 09 March 2009 - 02:51 PM
The question is - is there a way to connect the two different types of dovetails, or do I need to replace my HEQ5 mount head so that it can work with Losmandy D type dovetail?
Am I the only 8" SCT owner encountering this problem?
BTW, the plate scopestuff sell doesn't solve the problem since it's flat. Therefore - again, there can be only 1 screw at either side of the OTA attaching the two. They do not provide some radius blocks...
Posted 09 March 2009 - 03:25 PM
Here are three photos that I believe will clear things up for you.
All three show the mounting techniques for a C-11 using Losmandy "D" plate and saddle.
Here's the first showing the "D" saddle. The "V" saddle (Vixen, CG5, etc) is similar, but much smaller and less robust...
Posted 09 March 2009 - 03:27 PM
Posted 09 March 2009 - 03:31 PM
Or am I still missing something?
Posted 09 March 2009 - 03:36 PM
Posted 09 March 2009 - 04:40 PM
I wasn't able to find any V type dovetail that comes with radius blocks).
Take a look at the VCB8 here. If I'm not mistaken, this is what you're looking for, but you'd have to call Losmandy and see if those radius blocks will work for an 8" Meade or if he's making radius blocks compatible with Meade and hasn't yet updated his web page. Do you know any machinists?
Posted 09 March 2009 - 05:02 PM
From what I know, the VCB8 exist only for Celestron, but I guess I'll have to give Losmandy a call and ask him. Otherwise, it seems that VSCT13 is the only thing for my OTA, meaning that it will be attached to the OTA by one bolt on each end. Maybe it's enough. Maybe it's not. I have to say that I can't see myself putting my trust in a single bolt
So again, it's either getting some radius blocks for Meade (and I actually talked with 2 machinists today, and none of them gave wanted to produce a solution for me), or getting the D dovetail and finding a way to attach it to my mount (I am curious to see how TheMenace did it).
Posted 09 March 2009 - 05:12 PM
Posted 09 March 2009 - 05:35 PM
The 8" should work fine with one screw on each end as the ota does not weigh enough to cause any problems.
I would call ADM and see about the dual saddle.
The losmandy radius blocks caused me quite a few headaches,as they didn't match up with my ota.
I needed to buy 2 complete dove tails to get a set that match.
The losmandy radius blocks only use 1 screw on the corrector end of the ota,in their stock configuration,even for the 10" ota.
Posted 09 March 2009 - 06:39 PM
I'll check ADM's saddle
The 8" OTA weighs about 12lbs (I assume), which still seems a lot for these screws. I'll feel a lot better with the radius blocks holding my OTA...
As for the frustration with the Losmandy blocks - I just had a talk with a friend who spent a LOT of time trying to figure out how to attach these blocks to the OTA along with the dovetail, so this story is quite familiar
Thanks for the insight!
Posted 10 March 2009 - 07:39 PM
It's only been a week but it is still tight and have had no problems.
If you look in either the classified section or the swap section someone is selling the one you need for $50.00.
Posted 10 March 2009 - 08:32 PM
Still, leaving the OTA on two screws, with such a small base footprint feels to me like a disaster waiting to happen...
I think I'll go with the Losmandy type dovetail and a suitable saddle (it might cost a few more $$$, but eventually, it will quite my worries).
Posted 10 March 2009 - 10:18 PM
Once you get over 10" and add the extra weight of the losmandy dove tail,I really start to question using one screw through the ota to keep the heavy scope attached securely to my mount.
My current 10" sct looks like it was already dropped a few times already.
Posted 12 March 2009 - 09:55 AM
Thanks for the info guys. I really appreciate it!