My 190MN Imaging Rig

[adamsp123]

I am using the 190MN on a Vixen Atlux mount guided with that little 50mm Finderscope and QHY5v. Please note the oodles of cables!

Placing the camera and filter wheel "inboard" towards the counterweights saves much extra loading on the rig as does the finderguider.

Cheers for looking

[Deneb]

A beautiful Beast, & nicely balanced, it's corrector plate & having a camera at the end of it, does weigh a bit does it not ? I find my position of the mounting rings similar to yours.

Just need to get images done..

Nadeem

[simon84]

Looks fantastic, that looks like a lot of weight on the focuser, does it cope with it well? I really do like that scope. It was a hard choice when I got down to either one of these or the Equinox.

Looks like you have a nice secluded area there.

[adamsp123]

I am amazed how sturdy that focuser has been, partly due to the thickness and construction of the OTA, the camera/filterwheel stays put also when you tighten the locking screw unlike my F/4 newt.

[fatwoul]

A beautiful Beast, & nicely balanced, it's corrector plate & having a camera at the end of it, does weigh a bit does it not ? I find my position of the mounting rings similar to yours...

Strangely, mine is set up a lot more back-heavy, but I can't really tell why. Even with no heavy DSLR mounted up-front, my scope is still happiest with its tube rings such that the Schott logo is touching the front ring. The only difference is that I have an Astrozap dew shield hanging off the front, which is, I suppose, fairly thick plastic, and does crane quite a long way forward.

Balancing is a real issue for me. When I introduce a second scope for guiding I start to get headaches. I've always figured that, if you balance each scope individually first, and determine its centre of gravity, then you can balance groups of scopes much more easily. Bust as soon as you introduce a different eyepiece, or guide camera, etc, the whole system becomes unbalanced. Is there a sure-fire technique for this?

[Deneb]

... Even with no heavy DSLR mounted up-front, my scope is still happiest with its tube rings such that the Schott logo is touching the front ring...

Mine is rougly like that as well, but looking at Pete's setup the bottom dovetail seems a little shorter then the stock dovetail which is supplied or the ADM 14" dovetail which you can buy seperatly..

Nadeem.

[fatwoul]

True, Nadeem, the dovetail does look shorter, but, I dunno, the whole scope seems more evenly divided front-to-back than mine.

The biggest problem I have with mine is resolving the centre of gravity down the length of the OTA. What I mean is that, with my refractors, the eyepieces/cameras hang off the end, so are pretty much just an extension of the telescope tube. But with my MN190, all that stuff hangs off the side of the tube, meaning that the centre of gravity of the OTA isn't down the middle of the tube. I am having a really hard time making sure this centre of gravoty of the OTA/camera system intersects the counterweight bar axis, which would seem to be the way of ensuring perfect balance.

It's difficult explaining it in words. Does anybody know what I am talking about? Or does this C.o.G. issue not matter?

[Deneb]

Why don't you try rotating the tube so the focuser is facing the counterweight bar, load up your camera or whatever your going to use, then rebalance the RA & DEC. You might find it better this way.

Nadeem.

[adamsp123]

Mine is rougly like that as well, but looking at Pete's setup the bottom dovetail seems a little shorter then the stock dovetail which is supplied or the ADM 14" dovetail which you can buy seperatly..

Nadeem.

I am pretty sure the "standard" dovetail that came with it was slightly shorter. The Dovetail bar you see I got from Bern at MA, it is really big lump of material, I am not so sure that a longer dovetail will not have its own flex.

[robertm]

The main improvement I saw in balancing was to point the camera towards the counterweights. Doing that allows you to move the counterweights closer to the RA axis which reduces the inertia of the system. All balanced up my focuser is about 2" from the front tube ring. Personally I would only be concerned if I couldn't reach balance. A 50mm finder guider also helps a lot as you can virtually ignore it for the purposes of achieving balance.

I use the supplied dovetail to mount the guider and found a losmandy dovetail had more than enough rigidity, even with the stock tube rings, despite the small feet. I would imagine the ADM bar would be nearly as good.

Hope that helps

Robert

[Earl]

Its upside down

[adamsp123]

Sorry

Note slight red hue taken by a modded 1000D

[fatwoul]

I had another go at balancing this week.

I already have the camera/eyepiece in line with the dovetail bar (closest to the counterweights), but I tried fine-tuning this system with and without the finderscope and dew shield. The main purpose of the exercise was to practice balancing, to speed up the process, because the system will keep changing between different configurations. Hopefully within a month I'll be getting my pier... SO EXCITING!