Counterweight attachment

[astro mick]

Hi.

Anybody used or uses one of these.

Its used to attach a small Telescope to the counterweight bar,or indeed a guide camera.

I suppose the only drawback would be an observatory based scope,as the the walls may limit the targets chosen,with it being low slung.

Mick.

[pmlogg]

That is intended to fit onto a 20mm diameter bar as used in the Giro/Mini-Giro and Astrotrac systems.  I have used a pair of these (but with ADM MDS dovetails and clamps rather than the vixen clamp) on an Astrotrac plus wedge plus Mini-Giro.   On the Mini-Giro, with a longer bar than the standard one (any 20mm stainless bar will do) you can slide the bar back and forth through the mount to achieve left-right balance.  

If you used it on the end of the counterweight bar of a normal EQ mount balancing could be an issue depending on the weight of OTA etc. you wanted to use.  And some counterweight bars are only 18mm diameter.  There might not be enough friction to hold the assembly firmly in place a. to keep the OTA/camera on target and b. to keep it from falling off the end of the counterweight bar.  I have found that slippage can be an issue as the assembly is held in place by a small grub screw.  I suppose that it would be possible to drill and tap additional holes and use more grub screws but I've not attempted it.

[laser_jock99]

I've often thought of using something similar for putting an extra camera on the counterwieght shaft. I devised a clamp to hold a camera ball & socket head to the shaft - but never used it much (no spare cameras!!).

The one you have pictured is available from Teleskop Service if anyone is interested.

http://www.teleskop-express.de/shop/product_info.php/info/p229_TS-Piggyback-Cameraholder-for-D-20mm-Counterweight-Shaft.html

[reddoss]

I have heard about putting a camera on the end of a counter weight bar, but never seen anyone do it in all the years I have been imaging and going to star parties.

[astro mick]

One other drawback I can think of is that the Counterweight bar is stationary,so when the Dec axis swings to a target,the scope would have to repositioned each time,to alighn with the main scope.This could be very akward,and fiddly to do,and could result in slipping off the end of the bar.

Think I will give it a miss.

Mick.

P.S. I am of course talking about a GEM here.

[astro mick]

Further to my above post.

I should,nt have generalized the Dec axis of THE GEM mounts.

But I believe with the larger GOTO Mounts (ie) NEQ6 the counterweight bar does not rotate with the DEC axis.

Someone may correct me here.

Mick.

[ollypenrice]

I've often thought of using something similar for putting an extra camera on the counterwieght shaft. I devised a clamp to hold a camera ball & socket head to the shaft - but never used it much (no spare cameras!!).

The one you have pictured is available from Teleskop Service if anyone is interested.

http://www.teleskop-express.de/shop/product_info.php/info/p229_TS-Piggyback-Cameraholder-for-D-20mm-Counterweight-Shaft.html

I thought you used two canal boats and a caravan as counterweights!   

These strike me as a logical idea. (The OP's gadget, not the canal boats...)

Olly