My first Schmidt Cassegrain, any tips?

[M4lcs67]

Coming in on this post. I always struggle attaching my C9.25 ota onto the mount. Most of the time it is so difficult I am in a position where I nearly drop the tube while I am wiggling it into position. You really need three hands in order to do it safely.

Is there a technique that others employ in attaching the ota to the mount? Luckily I do have an ADM saddle (which I replaced the rubbish supplied one with).

I usually have the saddle horizontal with the clutches locked and the saddle tightening screws open. I then slide the dovetail bar in. Should I open the saddle more and sit it in as close as I can to it's final position and lock it then do the minor adjustments from there?

I assume attaching it in a horizontal position would be best? If it was vertical it could slip out.

I really put my life in my hands every time it attach it and I am always worried that the ota will fall out. Yes I do keep going around and checking and re-tightening all the locking bolts, just to make sure that none have worked loose.

Thanks for any comments, tips on how you do it.

[Dunkster]

Malc - I did myself an injury (actually, agitated an old one!) first time out with my C11... trying to bear wrestle the beast into the puck.

Then m.tweedy pointed me at one of these... http://www.ebay.co.u...=item3f178a6bd3

And I scratched my head. What you're paying for is the little clamp under the dovetail. Looks unassuming. All I can say is _invaluable_

Clamp one or two onto your dovetail the first time you use them, sort of in the right place. Position the puck vertically, loosen the puck clamp, drop the dovetail into the puck with the puck below the clamp (if one clamp), or between the clamps (if two clamps used) and tighten up the puck clamp. Nice and simple! Just never let go of the ota at any time, just to be safe. The NEQ6 is pretty beastly too with the tripod legs even slightly extended, so I find I can rest the ota on my shoulder and hold the handle with one hand, while tightening the puck clamp with the other.

Once you've got the ota in the balanced position, leave the clamp(s) on the dovetail and the next time you go to use your scope, you know where it should go, and it drops on the puck really easily, quickly and (relatively) safely. Much less hassle than leaving it to guesswork.

Oh wait, just occurred to me the C9.25 could be had in either Losmandy or Vixen style dovetails I wonder if he does a Vixen-style version?

Either way, I'd orient the puck in its home position and slide the ota in from forward and above, with you standing behind it (facing Polaris) - on the one hand, gravity is helping to slide the dovetail through the puck to its destination, but also you're there to catch/cushion it if it goes pear shaped

I should add that more seasoned EQ experts will undoubtedly have a better way

[Dunkster]

I am considering a dual speed focuser. I think in terms of AP it'll be more handy and will make adding a motor later easier. Plus it's not exactly a bank breaker

I got the Feathertouch for my C11. Not the cheapest thing on earth, but excellent quality piece of kit and makes it much easier to hit that sweet spot

[BlueAstra]

There's a video somewhere showing a method of attaching a Large SCT to a mount. Basically you get a chair or tall stool and sit the SCT pointing downwards on the chair so the mounting bar was vertical. You then drive the mount until the clamp is vertical, close to and parallel to the SCT. It's then easy to attach the SCT to the mount, with the chair taking all the weight.

[cgarry]

There's a video somewhere showing a method of attaching a Large SCT to a mount. Basically you get a chair or tall stool and sit the SCT pointing downwards on the chair so the mounting bar was vertical. You then drive the mount until the clamp is vertical, close to and parallel to the SCT. It's then easy to attach the SCT to the mount, with the chair taking all the weight.

Yes, that would be the one I posted in this very thread!

http://stargazerslou...20#entry1941872

Cheers,

Chris

[Zakalwe]

Malc - I did myself an injury (actually, agitated an old one!) first time out with my C11... trying to bear wrestle the beast into the puck.

Then m.tweedy pointed me at one of these... http://www.ebay.co.u...=item3f178a6bd3

And I scratched my head. What you're paying for is the little clamp under the dovetail. Looks unassuming. All I can say is _invaluable_

Thats what I use too. Those clamps should be considered a "must have" as they stop the scope slipping out of the saddle. The Farpoint version is much nicer though and it fits better.

http://www.365astron...ils-p-2170.html

I use them on all my scopes.

Stick the mount in the Home position- saddle vertical. Lock all the clutches, put the weights on, then lift the tube into the saddle. The saftey clamp will stop it from moving and you can steady it with one hand whilst tightening the locking screws. I also use an ADM Losmandy clamp....I wouldn't dream of putting my big C11 into a standard Vixen clamp.

[emadmoussa]

Thats what I use too. Those clamps should be considered a "must have" as they stop the scope slipping out of the saddle. The Farpoint version is much nicer though and it fits better.

http://www.365astron...ils-p-2170.html

I use them on all my scopes.

Stick the mount in the Home position- saddle vertical. Lock all the clutches, put the weights on, then lift the tube into the saddle. The saftey clamp will stop it from moving and you can steady it with one hand whilst tightening the locking screws. I also use an ADM Losmandy clamp....I wouldn't dream of putting my big C11 into a standard Vixen clamp.

Maybe you should make a video or photo guide... ?

I'm a bit confused here. What's wrong with the standard dovetail that comes with the scope? If I want to have a more solid set-up, what do I need? A Farpoint dovetail with clamps? How does this work?

[todd8137]

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[emadmoussa]

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Please STOP!! I got it, I got it...I promise :D

[M4lcs67]

Thanks guys. I have the ADM saddle fitted to my CG5. The Celestron one is pretty lousy, so on several recommendations I bought the ADM.

As it stands at the moment I wrestle it into position then lock everything off. I have a couple of pen marks that I have made, so I can get it somewhere near. Obviously it isn't an exact science and I have dewshield and dewtape on one end. And I switch eyepiece combinations throughout an observing session, so once you have the whole thing balanced, it could then be unbalanced by virtue of you switching to a different eyepiece. How wide are these additional safety clamps? As you can see from my photo of the rig, with me having an ADM saddle there isn't much room at the back of the ota (dovetail section)

Thanks muchly.

[Zakalwe]

How wide are these additional safety clamps? As you can see from my photo of the rig, with me having an ADM saddle there isn't much room at the back of the ota (dovetail section)

You put them in front of the saddle. It stops the OTA from slipping downwards when loading it.....

[Zakalwe]

[emadmoussa]

Excellent. Thanks a lot. That explains it all What difference does the AMD clamp saddle thingy make? If you kindly post the link please?

[Zakalwe]

Excellent. Thanks a lot. That explains it all What difference does the AMD clamp saddle thingy make? If you kindly post the link please?

Its a heck of a lot more stable and allows me to use Losmandy dovetails (my NEQ6 was fitted with the Vixen saddle only)

http://www.firstlightoptics.com/adm-guidescope-rings-and-systems/adm-dual-saddle-upgrade-for-heq5-and-eq6-series-mounts.html

[ollypenrice]

How could you make them? They're not just glass... o)

He made them in the way that was invented by the one-armed Bernhard Schmidt himself. You place a glass blank over a tube, excavate the air beneath the blank and grind a straightforward curve into the deformed blank. Once left to spring back into its natural shape you have a Schmidt corrector.

When I tried the binocular the glass was still uncoated but it will receive its anti reflective coatings at some stage. The gentleman in question is an optical engineer by profession. Don't try this at home...

While he was about it he ground new Edge-style secondaries and slowed the F ratio to 11 so that he'd have enough back focus to be diffraction limited even with the extended light path of the double diagonals needed for binocular use.

Olly

[faulksy]

He made them in the way that was invented by the one-armed Bernhard Schmidt himself. You place a glass blank over a tube, excavate the air beneath the blank and grind a straightforward curve into the deformed blank. Once left to spring back into its natural shape you have a Schmidt corrector.

When I tried the binocular the glass was still uncoated but it will receive its anti reflective coatings at some stage. The gentleman in question is an optical engineer by profession. Don't try this at home...

While he was about it he ground new Edge-style secondaries and slowed the F ratio to 11 so that he'd have enough back focus to be diffraction limited even with the extended light path of the double diagonals needed for binocular use.

Olly

theres some clever people out there olly

[M4lcs67]

Ah, ha. So you just have one dovetail clamp at the top. A very good idea as it covers several different functions. Not only does it act as a third hand, but also a memory lock so you know where to put it the next time you set up. Thanks alot....

[E621Keith]

Yep, this is the kind of lucky deals

I'm just curious, the ADM dovetail is screwed directly into the tube? Is it really enough to take the weight of the C11, say, if you want to use it as a grab handle?

I also noticed a lot of guys use some sort of clamps to hold the C11 dovetail on the NEQ6.

Celeston's dovetail bar is screwed directly into the tube as well, so there isn't much difference. The only big difference between the standard Celestron and ADM is that the ADM has radius blocks between the dovetail and the tube, so the dovetail is mounted further out which leaves a gap big enough for your fingers to go through.

Remember, dovetail is attached to tube rings using screws as well.