If you get a new camera don't forget to rebalance your scope!

[tomato]

That's what I did. I took an Atik 314 off my refractor and replaced it with a field flattener, and G2-8300 with filter wheel. I then couldn't figure why the tracking was poor until I checked the balance, it was seriously out (as you'd expect) in both RA and DEC. The Mesu is reasonably tolerant to inbalance but even this mount has it's limits! I needed to double the counter weight and radically move the saddle on the mount plate and relocate the guide scope but it's nicely balanced again now. The mount won't fit in the flight case anymore, but that's another story.

Just waiting to see what the next gremlin will be, I just love this hobby....

[gnomus]

Even small things can have a big effect on balance.  I kept making the mistake of balancing my gear with the lens cap on.  Not any more....

[carastro]

I am changing my kit around and going to Astro camps all the time, so I always have to check the balance.  I guess the danger is when you have a permanent set up that you don't change, you get out of the habit.

Carole 

[DaveS]

My DDM60 is *very* sensitive to balance, even down to the lens cap or cable loom.

Fortunately there is a very good balance tool built in to the software.

[tomato]

Thanks for the replies.

Gnomus,

I'm intrigued how you can measure the effect of the lens cap on the balance with presumably a Mesu mount, given the inherent drag created by the friction drive. Do you use a sensitive spring balance or do you have some clever software that uses the mount's encoders to measure overrun after a slew or something?

At the moment, with the power to the mount off, I just give it a gentle push in either direction in the horizontal position to estimate if it is  in neutral balance. It was so far out initially, I didn't need to give it any assistance, the heavy end would just keep moving.

[gnomus]

Hi Mr Tomato

When you first get the Mesu the friction drive does make you concerned that you might not be getting the balance quite right.  I did try a spring balance for a time, but I am not sure I believed the results I was getting from it.  Now I just do it by feel.

As regards the lens cap, the Esprit 120 uses a 'slip over' style cover that is made from some sort of metal.  It has some mass.  And, of course, what with the camera and everything else, the Esprit needs to be slid quite well forward, thus moving the end of the scope quite far from the pivot point.  (I remember learning about 'moments' about a hundred years ago.)  In any event, the addition of the relatively lightweight lens cap did make an appreciable difference to balance that even my tired old senses could detect.  

Now that I think about it, I suppose that this must mean that if you have one of those Flip Flat things, you probably need to balance with the Flip Flat in the 'Open' state.    Damn!  That means I'm going to have to go through this rigmarole yet again.

[ollypenrice]

20 minutes ago, gnomus said:

Hi Mr Tomato

When you first get the Mesu the friction drive does make you concerned that you might not be getting the balance quite right.  I did try a spring balance for a time, but I am not sure I believed the results I was getting from it.  Now I just do it by feel.

As regards the lens cap, the Esprit 120 uses a 'slip over' style cover that is made from some sort of metal.  It has some mass.  And, of course, what with the camera and everything else, the Esprit needs to be slid quite well forward, thus moving the end of the scope quite far from the pivot point.  (I remember learning about 'moments' about a hundred years ago.)  In any event, the addition of the relatively lightweight lens cap did make an appreciable difference to balance that even my tired old senses could detect.  

Now that I think about it, I suppose that this must mean that if you have one of those Flip Flat things, you probably need to balance with the Flip Flat in the 'Open' state.    Damn!  That means I'm going to have to go through this rigmarole yet again.

The time since our schooldays goes fast

So more than a moment has passed

Since I failed all my courses

On moments of forces

But my Mesu's in balance at last!

 

[andrew s]

Torque to me baby / I want to guide at night...

I have abused my Paramount ME by removing a Lisa spectrograph with two cameras attached to be replace by an eyepiece and it did not hesitate a micro second. Each design has its strengths and weaknesses.

Regards Andrew

[tomato]

The lens cap on my Altair scope is a  flat threaded aluminium  plate, not too great a mass but hanging on the very end of the scope (yes,  force x distance, it's all coming back to me now....)

Anyway, I'm looking at attaching a fixed bar along the scope with a moveable counter weight, as I don't like how currently half the saddle is now hanging out in fresh air instead of being nicely centred on the mount plate.

[tomato]

After my moan about balancing and securing the camera, it's amazing what a few hours access to machine tools can do.

An alloy baseplate now bolts to the existing scope rings with a pedestal at one end to take a small counter weight bar with a 2 kg weight. The plate has also been used to make a more rigid base for the guide scope mounting and I now have a lanyard in place to give me more confidence when removing the camera. The tiniest dab of Vaseline on the adapter threads has made the operation smoother, quieter and less nerve wracking. 

Just need to get to grips with the camera now.