Ahhh - because the Cheshire is quite a cheap unit and it relies on my eyeballs always being in the same position is my guess. The Hotech is a bit more ruthless on accuracy.

In a nuthsell I could look in the cheshire and believe collimation to be ok. The Hotech might suggest a small bit of tuning ( always to the primary). When the tuning was done the Cheshire would still show ok which would tend to make me think its my eyeballs at fault or that the accuracy is higher than the cheshire could acheive.

I should add that the Hotech was used plugged in with its 2" adapter whereas my Cheshire relies on the moonlite 2" to 1.25" adapter which while very good is not self centering. Its compression ring is good enough for most things but obviously introduces a small error againts the Hotech with its self centering system.

Thats all I can suggest really as the Hotech showed VERY consistent collimation of itself ( I tested it by rotating it a few degress at a time in the focuser while locked and it was always bang on target).

I would also suggest that secondary mirror rotation is the real peril with a laser. Its easy for rotation errors to creep in which will give a good laser result even when the secondary is badly misaligned to the focuser - thats why you have to get the secondary close using a sight tube or colicap and recheck after collimation is completed.

I havent deceided to buy a Hotech yet - if I were going to buy a laser it would be the one I'd buy - I just liked its quality feel and the fact its been properly engineered.

My reluctance isnt much to do with the unit - more to do with me having promised my partner I'd not go spending more cash for a while