Focuser Help

[PhilD]

I have a Skywatcher Explorer 150P. I’d like to upgrade the focuser from the current standard rack and pinion to a Crawford type (as an aside why is it called a Crawford, named after someone?). I don’t want to break the bank and bearing in mind the value of the scope would anyone have a suggestion?

[brianb]

Ummm, it's Crayford not Crawford, and it's named after the town where the original design was made.

Why do you want to change the focuser? R+P units can work very well (though not all of them do), Crayfords are prone to slipping when loaded with heavy cameras etc and both tend to have rather long tubes .... for Newtonians, especially when photography is intended, a low profile helical focuser can be more practical.

[Astro_Baby]

From Wiki.....

The Crayford focuser is a common focusing mechanism in amateur astronomicaltelescopes. It is named after the Crayford Manor House Astronomical Society, Crayford, England where it was invented by John Wall, a member of the astronomical society which meets there. The original Crayford Focuser is on display there.

The Crayford focuser was initially demonstrated to the Crayford Manor House Astronomical Society, and then descriptions were published in The Journal of the British Astronomical Association (February 1971), Model Engineer magazine (May 1972) and Sky & Telescope magazine (September 1972). Jack Wall decided not to patent the idea, effectively donating it to the amateur astronomical community.

There was an article on it in one of the astro mags a few months ago. Cant remember which one though.

Depends ho wmuch you want to spend. The ultimate are the Feathertouch focusers but they come pretty expensive.

Moonlite are good ( I have one ). They dont slip with heavy eyepieces and if your doing astrophotography they can have short focus tubes. A Moonlite costs about £250 all in and its rather good.

Theres also the Baader Steeltrack versions. Cheaper than a Moonlite. Cant comment really on them.

Sky-Watcher also do a dual speed Crayford upgrade - Stsve at FLO would be the best person to advise on that.

Really comes down to how much you want to spend at the end of the day.

I got a Moonlite with dual rate and its brilliant. Holds the heaviest eyepiece with ease and the motion is very smooth.

[PhilD]

Thank you both for your comments. I’ll have a look at your suggestion although the Moonlite seem a little expensive considering what I paid for the scope second hand. Again, thanks for taking the time to post your comments. I won’t forget Crayford now.

[johninderby]

Hi

I agree with the previous posts. FeatherTouch is the best for build quality, but MoonLite are very good as well. The Baader Steeltrack handles weight just as well as the Moonlite and is equal in feel and precision.

The Skywatcher is a nice focuser for the money, but not as smooth as the ones previously mentioned and doesn't handle heavy eyepieces as well. The dual speed crayford sold by ScopesnSkies now comes with two bases and is a bolt on replacement for a Skywatcher.

One thing to consider though is that cheaper crayfords such as the Skywatcher are designed to fit 8" and up tubes so they flatten a 6" tube a bit when they are bolted down but still work OK.

I've got a FeatherTouch and a Baader Steeltrack and had a MoonLite.

John