linear power focuser

[Jamie]

What is a linear power focuser?

Can someone please let me know the difference between the new linear power focuser and the present types on offer?

Thanks in advance...

[RobH]

IIRC, thay are the ones that are now fitted to some WO scopes.

Reportedly, they are prone to sagging and are generally not up to much.

I believe some even have bright blue LED's on them!!

What bright spark thought of that then, and what even brighter spark OK'd the idea :eek:

Cheers

Rob

[Jamie]

In what way do they differ from a crayford style focuser?

[blinky]

I have to totally disagree here...... I have the William Optics SCT Linear Power Focuser and it's very good with no sagging. The difference between a standard crawford and a LPF is that inside the power focuser there is a linear ball race that stops and sag - I sure if you google linear ball race you will get a good explanation of it, but other than the ball race to stop slop it is a standard focusser.

[Jamie]

Cheers Craig....

[RobH]

That's interesting Craig....can't argue with a man who actually has one!!

There have been all sorts of bad reports about these though, including from some who actually sell them (nameless of course).

Cheers

Rob

[johninderby]

The "linear power" type of crayford focusers that give problems (such as the DDG abominations!) are the ones that have just the the linear ballrace without any guide rollers that run on the top/sides of the drawtube. However if you have one of the "linear power" type with the guide rollers they do work very well.

The drawtube on the DDG focuser that I got rid of (replaced with a FT R&P) would twist about 5mm from side to side with just light hand pressure, what a piece of rubbish.

John

[argonaut]

Hi John,

I've had the new WO72FD DDG a couple of weeks now and it does have the new version of the DDG focuser with the better quality bottom rail. It does hold a 2" diagonal and my 28mm UWAN with no problems at all,no twist or sag in the focuser drawtube.

I believe WO had quite a few issues with the original. Has for the 'bright Blue light' there isn't one on the 72 DDG.It's the contrast between the black digits and the Grey background that makes the readout...readable.

Glen.