focuser: WO or GSO

[miki63au]

G'day all,
I have a dilemma: need a focuser for my 12.5" cassegrain.
The WO refractor dual speed fit the bill for ~A$350.
At Andrews the similar GSO dual speed refractor focuser sell for less than A$200.
Both has around 75mm travel and Crayford.

Is the WO price justifiable?

One more thing, I looking for a light weight 12.5" mirror cell.
Any suggestion?
Thanks,
Miklos.

[mick pinner]

l've got both on different scopes and the W.O is far superior and worth the extra.

[Omaroo (Chris Malikoff)]

Miklos - They are both great focusers for the money. I have three GSO Crayford-style focusers for some Newtonians lying around and they are mechanically very smooth - especially with the 10:1 reduction. I have the WO unit for SCT's actually attached to my home made refractor at the moment and it is a great bit of gear too.

There was a complaint running here on IIS a while ago in relation to a WO SCT focuser being "out of collimation". As the owner released the rotation lock and spun the focuser a laser colimator's beam moved in a circle around the center rather than on its own pin-point axis.

I should have had a longer thought about it back then and mentioned that I think I know what the problem was now. If you take apart a WO focuser, there are three screws around the periphery of the main barrel that physically hold the rotational part of the unit to the front - where the SCT threaded static portion is. These screws adjust to provide rotational resistance and eliminate slop. If taken apart, the three screws MUST be screwed back in properly - i.e. same number of turns each. If this is not done properly, the rotating part of the focuser can be left off centre - causing the centre to shift as it rotates around its own axis. If you leave these screws alone, you won't have any issues.

If it were my need to get another focuser, I'd go for another WO without hesitation - they are beautifully machined (like all WO gear) and will last you many years. The only shortcoming of these focusers is the overall length - as they can cause a camera to collide with the base of the forks if you aren't careful.

[miki63au]

Thank you all for the quick replay,
I want to use them for the old AO DK Cassegrain,
to replace the old Unitron focuser with the Unihex rotary
eyepiece holder.
The project is a long one. You see the original OTA was 35kg 16"diameter!!
Not managable...
My plane is to find a light weight cell for the 12.5"full Pyrex primary, and
make a flange adapter for the focuser. Of course with a limited budget...
Thanks for any assistance,
Miklos.

[acropolite (Phil)]

I have the GSO item on an ED80, the problem I have with the GSO is that the focus moves when the focus lock screw is tightened. I don't know if it is typical of the GSO focusser, but if I were buying again I would opt for the WO.

[[1ponders] (Paul)]

I've tried both the GSO/Bintel/no name and WO 10:1 on a refractor and the WO is much more satisfying to use, especially from a photography point of view. I found the less expensive brands had a slight but noticible amount of play in the fine focuser whereas the WO was very direct. Overall, using them photographically, I found them to be cheese and chalk.