Help - strategy for collimation

Long story but I need to collimate my C14. It has Bob's knobs installed so its easy enough from that perspective.

Having read the various "articles" I've gotten it close to collimation but I want to get it closer. So any strategies that others follow with a C14 or similar SCT?

One major issue that I have that you need to bear in mind - I have a fixed FLI PDF focuser (1" in 7000 steps) and the range is very small - in other words, I have very little by way of getting a star to be "out-of-focus". Within the range I have though, I can still get relatively dim stars with the familiar doughnut look to them.

Cheers
Dave

Try CCD Inspector Dave from the folks at CCDWare, there is a real-time collimation feature in which you can use in focus multiple stars. I think there is a free trial period.

Best wishes and clear skies
Mike

well Dave,
I use a webcam and adjust the collimation using the image on the screen, I then make the focus tighter and tighter, almost focused and make sure the the thing is still collimated, hope it give you some ideas.

Dave - that's exactly what I'm doing but the issue is a combination of the PDF focuser and the flop stoppers.

The process I follow is this:

1. Set the PDF to about 1/3 of its travel (about 2000 steps from home)
2. Release the flop stoppers, aim at a star and focus the 'scope using the manual focus knob
3. Tighten the flop stoppers.

At this point, my movement in focus can only be done using the PDF - If I back off to the home position, starts actuallt still seem fairly well focused. I can run the PDF forward to its limit of 7000 steps and the defocus isn't too bad - but still not really good enough for fine collimation. Bear in mind again that the PFD's 7000 steps happen in the distance of 2.5cm...

I think the last time I did it (a year or so ago) I must've just got really lucky and ended up with really tight stars across the entire field of view.

I'm going to try Mike's suggestion of CCDInspector (thanks Mike!) tonight.

I'll let you know how I get on but thanks for the reply.

Cheers
Dave

Yea, CCD Inspector is excellent.
Got mirror tilt and collimnation bang on using this program.
Free for 30 days too.
Doesn't get much better than that.

Just back in after using CCDInspector - wow! The most surprising thing was actually the ultra tiny Bob's Knobs movements that had to be made. Manually doing this, I was all over the place andprobably making way to many and too large movements. I got collimation to 1% in about 20 minutes. And the software was pretty intuitive - a quck 10 minute read of the help manual plus a quick phone call to Michael and I was away.

The only downside of the software is the price - its pretty steep ($180) and I'd only probably use it for collimation once every so often. Still, I'd have to say that it has saved me hours of fiddling about in the dark...

Thanks for the recommendation Mark and thanks for the tips Michael.

Dave