Rigid mounting a William Optics FFIV with the FLT scopes

[buzz]

Hi all.

I think the Field flattener IV is excellent but the 2" coupling is a let down and not a rigid enough system when you have a heavy camera on the end. In addition with the FLT98 and a feathertouch focuser, the focus tube is very close to being fully retracted and I was concerned about running autofocus routines.

The answer is a slim double male screw adaptor, coupling the 92mm and 2" screw threads. Why WO don't do one is a mystery.

Anyway, I had one designed and made up by Astro Phad for £110. It close couples the field flattener and the focus tube beautifully and has a scalloped ring with which to unscrew it.

Running CCD inspector, I have almost eliminated my tilt on the assembly.

The thread in the FFIV appears to be a SCT specification. My WO diagonal has an SCT adaptor, so I think I may just leave it in place.

I can recommend the upgrade to others with the same combination.

[steppenwolf]

Thanks, Chris, an interesting adapter as I have the same set-up as you.

[buzz]

here's a link to a picture of it in place

http://www.toinfinityandbeyond.me.uk/astronomy/Albums/Pages/equipment.html#32