Focuser woes

[Demon Barber]

Hi All having just fitted a new skywatcher low profile focuser to an Orion Optics uk 200mm f4.5 newt i find that i need a lot of back focus,i find it too cumbersome with all the tube ext etc, i was wondering if anyone knows of a spacer with a bit of depth to it,the skywatcher one is a bit of an awkward profile to pack, or would it be : A. Posible to move the mirror cell down the tube,or B. Shorten the springs and collimation bolts thus moving the mirror down the tube, a thicker version of telescope service`s newt adapt plate would be ideal,or is this going to be a one off special? any help appreciated,

Regards

Mike

[Moonshane]

hi Mike

I have to use a 50mm extension tube with both my OO newts which both have (after-market fitted) low profile focusers (one SW and one Antares - I probably prefer the latter).

If you have space in the tube, there's no reason not to move the (primary) mirror down but not too much or you will have the opposite problem of course.

Personally, I put up with the extension tubes, partly as the mirror cell in my 6" f11 is right at the end of the tube already.

[Demon Barber]

Moonshane, am sitting about to dismantle cell,i`m going to measure the springs,to see if i can shorten the bolts,that would give me enough wiggle room,i hope! It`s just with costly glass hanging off the end of multiple tubes i was hoping someone had already found a fix

Regards

Mike

[Moonshane]

I know just what you mean about the glass at the EP end. Maybe another option is to reduce the height of whatever holds the mirror off the cell? if it's relatively thick, maybe you could replace with some thin teflon too? maybe I worry less as with a dob, my eyepieces always face slightly upward.

[Demon Barber]

Sorry not explaining very well,thats just what i`m looking at doing there seems to be ample length available,the problem will be shortening the springs,i will let you know how it goes

ATB

Mike

[Moonshane]

nice one. some pics would be good if you can to see how you got around it?