Fork mount or German for video?

[mental4astro]

Hi all,

Not sure which forum to pose this question in, so I've put it here, :question:

I'm looking to make a rig dedicated to video astronomy. I have a couple of options for a mount, either the fork from an SCT or a German style (no more sophisticated than an EQ3 with an RA motor).

The gear I'll be using with it will be photography lenses (16mm to 300mm) and a couple of scopes (80mm f/5 refractor & 114mm f/4.5 reflector) coupled to my GSTAR camera.

Anyone have experience in this line of things? I am guessing that it would have similar applications to a dedicated astroimaging rig, :shrug:

Many thanks,

Mental.

[sgazer]

either will be fine, I presume you'll be doing something like 10s exposures (integrated), alt/az are easier to point in the right direction, especially it's goto. I use a Celestron SLT for this.

[mental4astro]

Thanks for that Lee. I've just got my hands on an old Meade fork from an 8" SCT. Back to the shed now to make the rig, :D

[tlgerdes]

Balance is going to harder and more fiddly with your scopes on a fork as it was designed with a certain centre point of the OTA for balance. Failure to get the balance right and you will destroy your motors, gearboxes and clutches very quickly.

[mental4astro]

Yeah, I was thinking of that Trevor. It will require a bit of tinkering to come up with a platform onto which I can make individual mounting blocks for each setup. I've done this for my photo tripod where I can swap between my various small scopes & big binos so each has their COG in line with the alt pivot point of the tripod head. Or, thinking on the run, a platform with a counter weight under it that can be shifted, much like the weight of a German mount.

Hmmm...

[tlgerdes]

Generally it is going to nose heavy, but you will probaly need to balance it on a couple of axis as well. Maybe start off with magnets if the OTA is steel.

[mental4astro]

Well, I got the old Meade mount working (thanks Barry), and I've fashioned a neat little platform for it. Just need to make a wedge for the mount. Here's a link to the project in the DIY forum:

http://www.iceinspace.com.au/forum/showthread.php?p=952495#post952495

I'm pretty happy with it. I also want to make the platform accomodate the 114 f/4.4 scope I've got too. Will make a fun little rig.

Mental.

[mercedes_sl1970]

Hi Alex - like what you have done.

Andrew