cheshire collimator versus laser collimator

[iwols]

whats the difference please

[almcl]

Um, price, possibly. 

I bought a Seben laser collimator some while ago. The only thing that can be said in its favour was that it was cheap.  It wasn't properly collimated out of the box (and the collimation screws were hidden under black gunk), the on/off switch didn't work reliably so the battery was always flat when I came to use it (didn't discover this till later) and instead of producing a compact , circular dot, it threw an indistinct fuzzy oval, so pretty useless overall.  More expensive (£100+) ones probably work better.  Basically it shines a thin beam of light from eyepiece via secondary mirror to primary and back again.  centering this on a target is said to align the scope.

The  Cheshire eyepiece, on the other hand, was nicely made and is still in use, but does require a bit more user interaction and has a bit of a learning curve.  It also needs a light surface to work with (no problem in my back garden, but trickier out on the windy dark sky site).  It also requires a bit more judgement as to when the cross hairs are aligned with the spot and is the spot centered in the doughnut.  You have to achieve this by looking through a small hole in the eyepiece.