Slide EP to focus question?

I seem to be able to smoothly focus with a nice fitting EP by just sliding and locking.

What are the disadvatages of a 'sliding' focuser?


Has anyone 'improved' the concept to the point that it is comparable to a helical focuser? IOW Why is a helical focuser superior to a 'slider'?

>>I seem to be able to smoothly focus with a nice fitting EP by just sliding and locking.

What are the disadvatages of a 'sliding' focuser?


Has anyone 'improved' the concept to the point that it is comparable to a helical focuser? IOW Why is a helical focuser superior to a 'slider'?
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You have a pretty slow scope and are probably using a low power eyepiece.

"Slip and Slide" Focusing is doable, twisting as you do it helps break the friction and reduce the tendency to over shoot.

Try it at 200x on a tight double star and one finds out why folks like positive focusers. The higher the magnification, the finer the control required.

A helical focuser acts as a gear reducer, taking large motions of your hand and reducing them by a factor of 50-100.

Since focusing can require positioning of the eye piece to within less than the thickness of a hair, the need for an precision method would seem clear...

Jon