Skywatcher SCT focuser and C9.25

[Marky1973]

Happily received a Skywatcher Crayford SCT focuser today to stick on my C9.25. Nice weighty focuser which should help with getting fine focus with the usual mirror problems...slight bit of play with the focus lock screw, but seems well-made and solid.

One quick question for anyone with the same set-up, when I screwed the focuser on to the back of the SCT, it doesn't screw all the way onto the thread on the OTA - as per the picture - is this usual, or a problem? It is all fairly solid, but just thought I would check I wasn't missing something....wouldn't want it falling off or letting stray light in if it is not properly fixed.

Cheers

Mark

 

[paul mc c]

I dont have the same set up,but do you have the focuser screwed on to the visual back?

[Dave In Vermont]

I have a GSO 10:1 Dual-Focus Crayford on my 12" LX90. It's the same animal as the Skywatcher-branded one. I don't have that much of a gap, but it has a little. It's nothing to be concerned about - as long as you're certain you got it squared-on to the threads of the visual-back on your 9.25" Celestron. If it screwed-on nice & easy without binding or force used, you should be gold.

Once you've got the main focuser-knob set to a good, rough focus with your new Crayford at the center-point when you do the rough-focus with the regular focus-knob on the SCT, you'll fall head-over-heels in love with the precision you can get from the Crayford! I'm assuming the Skywatcher Crayford you have is a dual-focus model? If so - you'll wonder why everyone doesn't do this! Mirror-flop will effectively be ancient history.

Happy Focusing -

Dave

 

P.S. - is this what it looks like?

 

 

[Marky1973]

6 hours ago, paul mc c said:

I dont have the same set up,but do you have the focuser screwed on to the visual back?

Hi Paul, no, I removed the 1/4" visual back - the thread on that woudl have been far to small, so this is straight onto the SCT thread at the back of the OTA. From what Dave is saying below, it looks like this might just be my usual overly fussy approach to "things needing to look right"! If only it had been clear last night I coudl have just gone out tested it!

Cheers

Mark

[Marky1973]

5 hours ago, Dave In Vermont said:

I have a GSO 10:1 Dual-Focus Crayford on my 12" LX90. It's the same animal as the Skywatcher-branded one. I don't have that much of a gap, but it has a little. It's nothing to be concerned about - as long as you're certain you got it squared-on to the threads of the visual-back on your 9.25" Celestron. If it screwed-on nice & easy without binding or force used, you should be gold.

Once you've got the main focuser-knob set to a good, rough focus with your new Crayford at the center-point when you do the rough-focus with the regular focus-knob on the SCT, you'll fall head-over-heels in love with the precision you can get from the Crayford! I'm assuming the Skywatcher Crayford you have is a dual-focus model? If so - you'll wonder why everyone doesn't do this! Mirror-flop will effectively be ancient history.

Happy Focusing -

Dave

 

P.S. - is this what it looks like?

 

 

 

Hi Dave, yeah, very similar to the GSO, and it is a 10:1 version. Really nice bit of kit so looking forward to trying it out. I soon discovered what the fuss was about with SCT mirrors when trying to focus on Jupiter to image it, so looking forward to trying with the Crayford....I just need to try and talk the perfectionist in me into being a little less of a worrier! :-)

Cheers

Mark

[Dave In Vermont]

You'll soon find it works perfectly! As for the bit of wobble in the focus-setting bolt - it's supposed to be adjustable so you can set it to hold a heavy camera at zenith without the pulling the draw-tube out, or just lightly enough to take up any play and be very smooth and stable with little load. Like a Plossl EP.

You'll get used to it in no time! And then you'll see people who spent 3X as much £££'s to get a Moonlight (or whatever) in 'GOLD!' - with no added benefit to it's focusing ability! And you'll end up on the ground - laughing!

Have fun -

Dave

[Marky1973]

Yeah I have had a little play with it and it seems capable of stopping slippage with a light tightening, it is only if tightened fully that the draw tube seems to shift slightly. To be honest the tube seems pretty solid without any tightening, so I think it should be pretty solid with just a planetary camera in it. Thursday and Friday seem to be clear here (at the moment) so will look forward to having a look through it!