Sky At Night

Hi all

done my first collimation last week and all appeared ok, I have one question , where should the focuser be.

Should in be fully in or out when using the laser.

Any help would be appreciated.

regards
tony

Premacy10 wrote:Hi all

done my first collimation last week and all appeared ok, I have one question , where should the focuser be.

Should in be fully in or out when using the laser.

Any help would be appreciated.

regards
tony

Interesting question. My understanding is that collimation is basically about ray tracing, so focus doesn't really come into it. So it shouldn't make any difference, so long as the focuser is square on anyway.
Once you have it collimated, does the focuser position make a difference?

I could well be wrong though

Hi Gfamily2

Yes when you collimate the lense the laser disappears into the hole when you move the focuser the laser then tracks across the face of the collimator

That was why I wondered if there was a correct position for the focuser to collimate.

regards
Tony

Premacy10 wrote:Hi Gfamily2

Yes when you collimate the lense the laser disappears into the hole when you move the focuser the laser then tracks across the face of the collimator

That was why I wondered if there was a correct position for the focuser to collimate.

regards
Tony

Again, with the warning that I've not done collimation myself, but my understanding is that if adjusting the focuser causes the laser to track across, it suggests that the secondary is mis-aligned.
According to this article, there are three steps to collimation, of which the use of the laser focuser is the third.
http://www.skyandtelescope.com/astronom ... telescope/

I'd be off the opinion that the farther the laser has to travel the more precise the alignment would need to be so I usually go for racked out but knowing that it's also down to how aligned the focuser is I rack in to see if it's different.