UPDATE: Eek, I meant to post this in the Beginner's Equipment Forum, but don't seem to be able to delete or move it.
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Hi peeps,
I'm probably obsessing over the collimation of my reflector (250mm diameter, 1250mm focal length, f/5), but who doesn't
Part of the issue is that I'm getting really crappy seeing conditions from the backyard at my new place (I've moved right next to Sydney airport - yeah, bad move) and so I'm not happy with the detail I'm seeing, even on planets like Jupiter and Saturn - though I can see bands on Jupiter and make out some bands on Saturn and just spot Cassini's Division.
I'm trying to make sure my scope is collimated properly though to rule that out as a possible reason for the poor detail I'm seeing, and I'll be making a trip to properly dark skies soon to see what I can see with much improved conditions.
I'm using a long tube Cheshire collimator. I'm pretty happy with the secondary placement and then getting the primary tilt right, BUT I have a bit of an issue with the secondary not being perfectly circular though the cheshire tube once I'm done. I see a slightly elliptical shape for the secondary - and this seems to indicate to me that the secondary isn't tilted in such a way to the sight tube that it appears circular, i.e. it's not perfectly perpendicular (I hope this all makes sense). I've played with the tilt on the secondary for ages, and it always becomes slightly elliptical when I've lined up the centre of the primary. It's like some kind of offset.
Can this happen? Does it matter? I'm really not sure, some images I see in collimating instructions seem to show the secondary as slightly elongated, and some perfectly circular.
Thank you to the collective collimating brains, in advance.