Focusser - seems a bit coarse - any solutions?

[JOC]

I don't know if it is a 'real' problem, but would it make sense if I said that I felt the focuser on my telescope seems a little 'coarse'?  It's almost as though it adjusts in tiny notches, and sometimes when I'm focussing on something I find myself wishing that the focus was a bit 'smoother'  Almost like the smooth sort of adjustment you get in a camera lens.  Does that make sense as an observation and can changes be made to make the focuser on the telescope run, I guess 'smoother' is the word I am looking for - i.e. to be almost infinitely adjustable - if so, how please? 

[richyrich_one]

 

[iapa]

disregard, I was thinking it was a R&P focuser. duh!!

I think this is a rack and pinion focuser (R&P).

How to improve on a Focuser entry level Refractor telescope - this is an R&P focuser so should apply

there was also one by Dion of  Astronomyshed within a posting about improving the Skywatcher startraveller 80

 

 

[Pete Presland]

You could always upgrade to a Crayford type focuser, with a 10-1 fine tuning knob if can not get your stock focuser how you want it.

[richyrich_one]

Thought it was already a crayford on a Skywatcher Skyliner 200P (8") FlexTube GOTO ??

[iapa]

21 minutes ago, JOC said:

I don't know if it is a 'real' problem, but would it make sense if I said that I felt the focuser on my telescope seems a little 'coarse'?  It's almost as though it adjusts in tiny notches, and sometimes when I'm focussing on something I find myself wishing that the focus was a bit 'smoother'  Almost like the smooth sort of adjustment you get in a camera lens.  Does that make sense as an observation and can changes be made to make the focuser on the telescope run, I guess 'smoother' is the word I am looking for - i.e. to be almost infinitely adjustable - if so, how please? 

Try this?

Improving A Skywatcher Crayford Focuser

 

[Knighty2112]

If it's a rack and pinion focuser, you can slacken off the four screws holding the tension spring in place underneath the focuser. Similarly if it is a Crayford focuser there is one main grub screw that alters the tension that would make it smoother.

[Louis D]

Most likely there's debris of some sort on either the "pinion" or the "rack" (yes, I know it's a Crayford and doesn't have either, but what do you call them?).  On mine, the black anodization had flaked off the focuser tube and deposited itself on the shaft, so I cleaned up both and the original smoothness returned.

[ronl]

If you try the method shown in the video above, it will make an improvement, but if it's not

to your satisfaction and you still find it hard to get perfect focus, then one of these will definitely

help, http://www.365astronomy.com/Dual-Speed-1-10-Microfocus-Upgrade-Kit-for-Skywatcher-Crayford-Focusers.html

it's the cheapest way to upgrade your focuser. 

[Dave In Vermont]

For a R&P Focuser, this may help:

 

And for the Crayford's:

https://www.youtube.com/watch?v=ofOSAMlqZWw

I hope these may help.

Enjoy,

Dave

[rockystar]

my vote would be with Knighy's suggestion - try adjusting the center grub screw on the plate that holds the focuser wheel, see if that helps (don't go too far though, other wise it will slip)

[JOC]

Hi rockystar, Yup, I think I'll try the easier things first.  It's not that I won't strip things apart and try other things, but when I start with something that basically works and is quite expensive I do worry about doing some and indelibly wrecking something expensive that starts of as basically useable just to fix a niggle.  Admittedly the smoothing of the flat side of the moveable part of the focuser looks like it should do the trick, but it does seem a rather brutal solution (though we do have  bit of a  metal workshop here and could easily work the filing solution, its the pulling it apart and getting it back working again that concerns me!.) 

[ronl]

The Crayford is quite a simple focuser, quite easy to dis and reassemble, and it's just

four hex screws to take it apart, it's good to do these little modifications, it gives you

confidence to do other stuff on your scope. 

[richyrich_one]

And what else is there to do when it's cloudy?!

[JOC]

So I won't indelibly break my working telescope if I undo the screws and pull it all apart and try to reassemble it then?  I wish I knew an experienced astronomer locally!!!

[rockystar]

The way I see it, if it has screws, then it's meant to be taken apart and put back together

nails and glue are a different matter.