Feathertouch focuser

[Lance Bridwell]

Hi, This is all new to me. I recently purchased a Starlight Instruments Feathertouch focuser for my my Celestron Nextar 8SE.

I was having trouble obtaining a decent focus with the focus provided with the scope. Any advice or tips with this would be greatly

Appreciated.

Thanks in advance

[Dave In Vermont]

Get the focus from the focuser on the main-scope as close as possible - after already centering the focusing-travel of the Feathertouch to near it's midway-position - simply put: Rack it out to the about the middle of it's travel.

Now try focusing by using just the Feathertouch-focuser. That should do it.

I suggest using a low-power eyepiece for this your first time. Minor adjustments may be needed from time-to-time.

Dave

[alanjgreen]

Lance, have you bought a feathertouch "crayford" to fit in addition to the standard, or have you bought a "microfocuser" that replaces the original?

 

If its the crayford, then Dave has it right but maybe his steps could be clearer

(1) screw the feathertouch to the back of the 8SE

(2) turn the feathertouch focuser knob until you have the available in-out travel near it's midway-position

(3) use the 8SE standard focuser to get the focus as close as possible on a night sky object

(4) from now on, only adjust focus by using the Feathertouch focuser.

Step (3) moves the scope mirror to the near focus postiion (it must be done at night on a star). The mirror is now left in this position and you need not touch the standard focus knob again. There is enough in/out travel in the feathertouch because you centered it at step (2)

By adding the crayford you have increased the weight of the back end of the scope, so beware it may drop down quickly when you loosen the clutches on the scope.

 

If its the microfocuser, then there should be a CD in the box with instructions for removing the standard knob and fitting the replacement feathertouch

 

[alanjgreen]

If you still have problems with focus, then maybe the scope needs collimating?

Put an eyepiece in that gives at least x250 power and point the scope at a mid brightness star.

de-focus slighty (less than a quarter turn of the fine focus), have 1 or 2 nice round circles appeared around the star? or are the circles uneven? or are they not circles at all?

if you don't see nice round, concentric circles then your scope is out of collimation.

 

You can follow Ed's Guide to SCT Collimation to put it right.

Hope it helps.

[Dave In Vermont]

True - If you bought just the Feathertouch Focuser knob, the same advice hold basically.

Set the main-scopes' focuser at about mid-point, then install the Feathertouch - also set to about mid-point. Now try the focuser.

You should be golden!

I'd suggest, for a Star-Test, a magnification of about 200X. And on a star that will still pretty much stationary. Polaris (alpha-Ursa Minoris - mag. 1.99) is the classic-choice.

Enjoy! This niggly stuff willpass quickly,

Dave

 

[Lance Bridwell]

9 hours ago, Dave In Vermont said:

True - If you bought just the Feathertouch Focuser knob, the same advice hold basically.

Set the main-scopes' focuser at about mid-point, then install the Feathertouch - also set to about mid-point. Now try the focuser.

You should be golden!

I'd suggest, for a Star-Test, a magnification of about 200X. And on a star that will still pretty much stationary. Polaris (alpha-Ursa Minoris - mag. 1.99) is the classic-choice.

Enjoy! This niggly stuff willpass quickly,

Dave

 

HI Dave, thank you so much for the advice, I'll try your tips as soon as I can get some decent weather, I, live in

East Texas and has been rainy and cloudy for close to a month,

Thanks again, Lance

[noah4x4]

Best accessory I have purchased. Ironic that it was the last. I bought loads of junk before it reached the top of my list of priorities.  

With hindsight, all I ever needed was StarSense; Televue 8mm Delos; 12mm Delos and 32mm Plossl...and a Feathertouch MicroFocuser.

So well before completing that set of must have EP'S of which 60% will be used only once, do invest in one of these.

[Dave In Vermont]

I've never worked on a focus-knob on Celestron telescopes, but I've re-built one's on Meade LX-series SCT's. I installed Pete Peterson's EZ-Focus:

http://www.petersonengineering.com/ez_focus_kit.htm

I'd suggest reading-up on these. Amazing where some companies try cutting-costs!

Dave