Collimating with older eyes

When collimating a Newtonian, one of the recommended methods for adjusting the secondary tilt is to make the primary's center spot line up with the cross hairs in the sight tube.

I find that this is practically impossible to do well. First of all, I cannot simultaneously see both the center spot and the cross hairs sharply: if I focus on one, the other's a blur. This makes their alignment unclear (pun intended).

Secondly, there is the potential for further error if your eye is not centered within the peephole in the sight tube.

Together, these error might result in misalignment by up to one degree (but probably less). Is this critical for an F/4.5 scope?

Are there any tricks for working around these issues? I know that there are other tools I might use, but I'm trying to get the most from this one for now.

Allen

Hi Allen
Old eyes here too, and I fully understand your situation. I use the cross hairs to get me in the ballpark but then I insert a laser to hit the primary center spot and also use the return beam to hit the 45* face for roughing in the primary. I switch to the cheshire and make primary adjustments then on to an autocollimator. At this point I usually only have to make very slight adjustments to the secondary to get the stacked donuts and I'm good to go. However, sometimes if I have a lot of trouble getting the donuts to stack I may have to make very very slight adjustments to the primary then retry the secondary adjustments again. In my f/5.47 this works fine, but I've been thinking of going to the barlowed laser method instead of the cheshire, which I hear is more accurate. In your f/4.5 this accuracy is even more important.
Hope this helps
Buck