Is this my primary or secondary out of collimation?

[blinky]

Im using live capture on an out of focus star - I can see the big circle (I assume the primary) is presenting a circle, but the smaller shadow (assume the secondary) is not - does this indicate the secondary is not collimated?

 

 

[Peter Drew]

If the telescope is of reasonable size and relatively fast focal ratio the displaced shadow might well be showing the offset of the secondary mirror.         🙂 

[blinky]

That has just dawned on me in the last 5 mins after packing it all up and coming inside!  I think I made it slightly better and the stars look round etc - how can you tell if a newt is in perfect collimation if the secondary is offset?  I assume mine is since its an F4 scope.....  I originally used one of those co-centre devices and tonight made tweaks to the primary and secondary - Im now worried that I should have left it alone after collimating the secondary with the cocentre and the primary with the laser and Ive made it worse - but Im telling myself the stars were round and the out of focus star looks better now than it did and to leave it be and not let the laser near it till it needs recollimated!  Does that sound good?

[Starflyer]

I always struggled with getting the secondary exactly centred and appearing as a perfect circle, that's why I bought the concentre device Craig.  I always struggled with a Cheshire on the secondary, and found a laser to be worse than useless.

Treat yourself to a concentre for xmas 😃

Concentre for the secondary, decent cheshire for the primary and then star test.

[blinky]

To be honest I could not get it completely centred in the co centre either!  although I did sort the rotation and make the secondary round.  Really need a clear night to star test now, clouded over immediately after I collimated!

[Craig a]

I have an f4 Newtonian and honestly wouldn’t even touch a lazer for collimating the secondary I do use the barlowed lazer to do the primary,you should be able to get the secondary centred under the focuser, I used a concenter for the fist time last week and got the secondary perfectly centred and round under the focuser, I wouldn’t use the concenter to do the primary though as the movement of your head looking through it isn’t stable enough to to keep your eyes fixed looking at the centre circle hence the barlowed lazer is a better way of doing the primary, that’s my findings anyway hope it helps

by the way using the concenter has got my secondary looking the best it’s ever been under the focuser 

[blinky]

I could not quite get the secondary centered, the screw it right up against the secondary holder.... then it dawned on me, the focuser I have is a Baader steeltrack for a frac, but Bern said it fits the same thread on the newt I have. I think I might need to adjust that a fraction and centre the focuser.

[Craig a]

Doesn’t sound right to me having to have the secondary screwed right up against the holder, to square the focuser properly on tube you need to take the secondary out and mark the point directly opposite the centre of the focuser hole which means taking the focuser off the tube aswell, there are vids on YouTube of how to do it, but I wouldn’t be happy with a secondary that’s butted up against its holder, doesn’t leave much room for adjusting the secondary does it, what Newtonian is it you’ve got?