Bobs Knobs

[Radders]

Just about to order some Bob's knobs for my Celestron CPC 800 and I've looked at where the screws are and it has the Fastar logo on the front. Now on the Rother Valley Optics site, the Fastar is the Edge HD version. Are these ok to order for mine or is it different?

Paul

[Northern Soul man]

Hi Ya Paul, have a look at the bobs knobs site in the US, it shows you all you need to know about size, diameter and I think, thread pitch - I ordered mine from a UK site once I had the size for the 1100 - the Fastar logo just means that the secondary can be removed and the Fastar camera can be placed where the secondary fits - I think that you have to check on the actual thread size whether it be metric or imperial as different models have different size bolts fitted, just check on Bobs knobs site for sizes - it shows which type of secondary you have - I ordered from the UK when I found which thread size was needed and replaced the bolts one at a time - the only down side was that the secondary cover ( the small cover in the centre of the corrector) could not be rotated into place to hide the secondary screws - but the actual corrector cover ( the one which covers the whole of the corrector) could and can be used.

I think in the last couple of years my collimation has held very well - just make sure when you have replaced with Bobs Knobs or the equivalent, you make sure you concentrate on bolt tension as well as mirror alignment - the tension is very important - if you can get this right - collimation will hold very well - even if you transport the scope to dark skies - correct tension will hold the secondary - its hard at first when you have to keep tension and alignment in mind whilst adjusting - but remember,  your only adjusting one mirror - get tension first, then on a star test you may only have to make very small adjustments - maybe only a 1/16 of a screw turn to get it spot on.

Paul.

[damnut]

Oh and replace them one at a time...

[Mark in Macc]

I got mine from Bob himself in the U.S. Free postage from what I remember and came within a week.

[Radders]

Thanks for the replies guys. I'll email them direct later.

Paul