Counterweight Extension Bar EQ5

[Astro-Geek]

I can't quite balance my 200pds on my EQ5 mount when my DSLR is attached. (+ Coma corrector and Telrad).

I have the two 5kg weights right at the end of the counterbalance bar and it's not bad, but I'd like to have a little more leeway.

I've searched the web and forums and although there's quite a few mentions of counterweight extension bars, I'd like to just check on here before I take the plunge.

I've upgraded my EQ5 with Synscan goto motors and control unit, so I guess I can now call it an "HEQ5" even though the metal parts are still standard EQ5.  It does appear to be a later model, as it has the larger M12 tapping and safety knurled nut on the end, rather than the earlier M6.

I've measured it with a digital vernier, and the bar is 19.96mm diameter.

I think that the "Counterweight Bar Extension for Sky-Watcher NEQ6" Part Number:  20858 will fit,

https://www.firstlightoptics.com/sky-watcher-mount-accessories/counterweight-bar-extension-for-skywatcher-neq6.html

.........because a footnote states "Note: This might fit HEQ5 mounts but only newer ones, please check the diameter and thread dimensions above to see if it matches your mount."

However, it also states " The extension is 18mm in diameter with an M12 thread. "

.... mine does have the M12 thread, but it's 19.96mm diameter, not 18mm ??

[Demonperformer]

FLO are quite good ... drop them a query about it.

[Waldemar]

You would be better of to get another cw. Better have more weight closer to the mount then less further away.
Many references to this effect called inertia, can be found here on SGL

Edited March 23, 2019 by Waldemar

[Cosmic Geoff]

I am curious to know if the "proper kit" checks out. I bought a long M12 coach bolt and found a bit of 18mm tube so I could balance my 203mm Newtonian on my EQ5 with one 5Kg weight.  It works okay for occasional use.

[Astro-Geek]

Thanks for the replies.

Yes, I've read several threads about adding extra weights rather than extending the bar because of the inertia effect.

I actually do already have an extra 5kg weight, (making three in all), but I was reluctant to clamp it on, not wanting to increase the overall weight on the EQ5 RA pivot even more.  Extending the leverage by just another inch or so seems a preferable option rather than having three closer to the pivot.  I can't claim any firm scientific basis for this, and I do appreciate the proven fact of the inertia.  It also makes the whole shebang almost 5kg lighter for moving around, even dismantled.

28 minutes ago, Cosmic Geoff said:

I am curious to know if the "proper kit" checks out. I bought a long M12 coach bolt and found a bit of 18mm tube so I could balance my 203mm Newtonian on my EQ5 with one 5Kg weight.  It works okay for occasional use.

That's a thought Geoff.  I even have some M12 bolts and studding, so if I search through my shed I may find some 18-20mm tube that I could adapt.  That way I could just add a semi-permanent 75mm or so to the existing length, that would do the trick. ?

afterthought -  If I use the studding, I could even replicate the existing safety screw feature with an M12 wingnut on the end.

Edited March 23, 2019 by Astro-Geek

[Erling G-P]

Have you rotated your tubus so the camera is on the 'inside' (closer to the counter weights) ?

I had the exact same problem with my 200 PDS / HEQ5Pro when I got it last year, and initially went with the standard, outside position of eyepiece / camera.  Rotating it to the inside solved it without need for extra weights and/or extensions, although it does place the finderscope, eyepiece & camera in akward positions at times.

[Astro-Geek]

No, I hadn't tried that Erling.

Yes, quite a good solution when just using a heavy DSLR, I must admit.

It would also solve another RA imbalance problem that the standard counterweights can't compensate for.

When I have the eyepiece holder at the normal comfortable tube rotation position, it sticks out at right angles to the tube's axis, so it's way out to one side of the OTA's centre of gravity.

However, as you say, when the eyepiece is used at that rotation it's very awkward. and I have the same counterweighting problem with my binoviewers.

It wouldn't be a problem with a Dob mount, low to the ground, looking from above, but pretty awkward with an EQ5, looking from underneath.

Edited March 24, 2019 by Astro-Geek

[philhilo]

I love SGL, most of those common problems have been solved, turn the OTA around. Yep I have a HEQ5 Pro and a 200PDS and was looking at extension bars - now this solution might just solve the problem. I do have an EQ5 as well but the weights don't fit the HEQ5 bar.