Lightbridge modifications

[Graeme Bluestar (Graeme)]

Hi all,
I have an equatorially mounted 16" Lightbridge which is used solely for imaging with an Atik 460EX camera. The OTA is still fitted with the original crayford focuser to which I modified an Orion electric focuser kit.

I'm still not completely happy with this setup, and have been considering removing the secondary mirror and replacing it directly with the Atik. My question is has anyone have any experience with this type of modification, and is there any type of off the shelf electric focuser assembly that I could use with just minimal modification. I have a basic workshop where I am able to perform such modifications, but not too confident on trying to make something basically from scratch!

[billdan (Bill)]

Hi Graeme,

The only commercial ones I have seen has been from Van Syke Engineering, they do motorised spiders but I am sure you could buy just the focus motor off them.

http://www.observatory.org/spiders.htm

Others on CN have done similar to what you want to do with manual helical focusers.

Cheers
Bill

[Atmos (Colin)]

If you remove the secondary you are going to have to replace the spider veins with something quite substantial to be able to hold a focuser, the extra back focus and possibly a corrector. You may be better off making the struts an extra 8" longer to accomodate for the extra back focus required. It seems like a lot of effort for quite minimal improvement.

What is it that you're hoping to improve?

[peter_4059 (Peter)]

Originally Posted by billdan

Hi Graeme,

The only commercial ones I have seen has been from Van Syke Engineering, they do motorised spiders but I am sure you could buy just the focus motor off them.

http://www.observatory.org/spiders.htm

Others on CN have done similar to what you want to do with manual helical focusers.

Cheers
Bill

Looks like VSI is no longer operating as a business.

http://www.observatory.org/index.htm

[billdan (Bill)]

Oh dear, that's terrible bad luck that happened to them. I hope they had insurance and can recover in the future.

[Graeme Bluestar (Graeme)]

Bill,
Just had a look at the Van Slyke website- it certainly does not look good for them.

Colin,
Yes, I have been considering lengthening the struts as you suggested. I want to eventually also install a 2x barlow into the system and must admit I'm unsure as to what extent camera & barlow & 2" to 1.1/2" reducer will affect the final image, hanging off the side of the OTA as it is. Perhaps an aftermarket focuser in place of the Meade unit would be sufficient?
Graeme.

[billdan (Bill)]

Hi Graeme,

I tried imaging behind a 2X Barlow once and wasn't very impressed, the chromatic aberration was disgusting. I suppose it depends on the quality of the Barlow, mine was cheap. I think the Powermates have better quality glass in them and may better for imaging.

Is your concern the extra weight on the focuser causing flexure? This could be remedied by supporting the camera with springs from the camera to the UTA.

Cheers
Bill