Yet another SCT collimation question

[Joves]

Hi folks,

Sorry to start yet another SCT collimation thread, but I have a quick question, if I may:

Is it normal to achieve what look like almost perfectly concentric ring patterns on one side of focus, only to then find the patterns on the opposite side of focus looking quite out?

I'm assuming this shouldn't be the case if I'm wanting as close to perfect collimation as possible and wonder if there are any tricks to achieving nice concentric rings on both sides of focus please?

Any advice would be much appreciated.

Thanks in advance,

Aaron

[alan potts]

Arron,

On my scope i only ever collimate on one side of focus and as long as you have your mirror shadow smack bang in the centre then it is fine. I increase the magnification as I get closer to what i want.

I always collimate with the diagonal as they never need to move about on our scopes and its easier.

I start with about a 35mm EP then 20mm then 10mm and finish with anout 5mm on the same star. When you get to the short end only the very smallest turn is needed.

Do you have the eyepieces??

Alan

[Joves]

Thanks heaps Alan, that's exactly the answer I was hoping for! Deep down I knew that trying to get it perfect either side of focus was probably going to see me take to the scope with a bat. I'm not a violent person, but every man has his limits!!

Actually, you know what... I think I might buy a set of Delos as my 'collimating eyepieces'!!

Thanks again, Alan!!

Aaron

[alan potts]

Arron.

So that's how you lot get so good at cricket.

Now that would be a world first, a set of delos for collimation. Funny enough this is the only time I really use single figure eyepieces in mine. I used 8mm once on the Ring M57 but other than that I never go below 10mm (X304)

Alan.

[Joves]

I'm the same, Alan. Rarely put anything higher power than a 10mm EP in my LX, which only takes it to 250x. I can occasionally get away with an 8mm, but at 312x, there are few nights or objects that seem to warrant it.

Now the refractors are a different story. They regularly see the single digits, right the way down to the 3mm, which gives a modest 180x. The 2.5mm Vixen LV doesn't see a lot of light. The 4" focal length can handle it, but it lacks a little in aperture to provide a very impressive view at that magnification. Perhaps a darker sky would help in that regard.

Aaron