Celestron 102SLT moving tube without power

[astronomit]

Hi all.

Just a quick question if anyone could help us out. I've been reading through the manual for the Celestron 102SLT, and it says that the optical tube can be moved by hand if you lose power - but I've just tried to move the tube, and it almost feels like you have to put quite a lot of pressure (and I mean quite a bit) just to move the tube up and down - plus you can hear the gears as it moves (which I would kind of expect). Question is - should it be this hard to move the tube? I'm just thinking that if the power supply were to fail, then if you couldn't move the tube by hand, then you're totally reliant on power.

Also if it is this hard to move the tube, then would it also not make it difficult to try and balance if heavy eyepieces, etc, were added?

Any advice/thoughts would be great.

Cheers,

Tim.

[astronomit]

Ah - looks like this is now solved - there's a nut which is attached to the mounting bar (hidden by the tube clamp tightening knob), which can be tightened to give more friction - loosening this nut means that the tube can be moved without power. I just wanted to check this as I thought I'd be stuck with not being able to use the scope if the power went!

Thought I'd just share this!

Cheers,

Tim.

[dph1nm]

As far as I remember, although you can move it up and down by hand, you cannot move it in azimuth without risking damaging the drive.

There is some limited balance adjustment possible by moving the dovetail attached to the OTA up and down in the clamp, but I have put a set of Skywatcher rings on a longer dovetail on mine. This makes it possible to balance a camera, 2" eyepieces etc

NigelM

[astronomit]

Hi Nigel

Thanks for the reply. Yes, I just wanted to move it up and down, but I was just thinking of how you would balance if you couldn't move the tube??!!

For your tube rings and dovetail do you just add the accessories that you are going to use on the tube, then loosen the nut under the tube tightening knob and move the scope either forwards or backwards to get balance? Or is there another way which you use? I was thinking of getting rings and a dovetail at sometime in the future - what size dovetail did you get? Did you have to make any modifications to it for the scope/mount?

Thanks again,

Tim.

[dph1nm]

I think I used a medium Skywatcher dovetail which I had going spare. You could use the longest one I guess (there are three sizes available I think). This (and the 4" Skywatcher rings) fits nicely over the existing dovetail (which as far as I can tell is permanently attached to the tube) and slots into the mount where you would normally put the existing one (so the whole tube is an inch or so futher out from the mount arm). To re-balance you can then either slide the tube up and down inside the rings (you hit the dew shield if you go too far) or move the long dovetail up and down the mount arm (this movement is limited by the bolts on the tube rings getting in the way). Between the two adjustments you can change the balance point a reasonable amount.

One day I will take some photos to make this clearer!

I also added a Skywatcher motor focusser. This helps quite a lot, as the the mount can be quite wobbly.

NigelM

[astronomit]

Thanks again Nigel - I've ordered a motor focuser as I'd read about (and experienced!) the wobbling issues with the mount - so I'm pleased that this should help quite a bit!

If you could get some pictures then that would be great - I know it sounds a bit silly, but I'm just trying to find the best way for balancing, so that the motors aren't too stressed, and that you can still track an object with the goto option!

Thanks again,

Tim.