Well.. first night tonight with the crayford in action, and I've having a few issues with it. I can't seem to get enough travel to focus with the 9mm or 15mm barlowed, the 9mm is right at the end of the travel. Has anyone had this issue with the 8" before? I've heard that you can move the primary, would this help? Is it hard to do?
Im guessing insufficient inwards travel, meaning that the path from primary to eyepiece is too long. Check that your secondary mirror is properly positioned under the focuser first, then you may be able to get a few more mm by loosening the main collimation screws on the primary cell. Be careful you dont go too far and unscrew them right out of the mirror cell.
I'm having no problems with my GS Crayford. It appears to have approximately the same travel as the R&P I replaced so I would be looking at the position of your primary due to repeated collimation creep. You may have to move it up or down the tube, depending on whether you have too little in travel or out travel.
using the 9mm it focuses just before the end of the outward travel... anything under 9mm, i.e barlowing the 9mm or 15mm i just don't have enough outward travel.
Before you do anything else, undo the bottom of the two screws on the underside of the crayford. The top one is to adjust focus tension and the bottom one is a focus lock. This focus lock can cause the drawtube to not fully extend if it is part way in.
This is the biggest weakness I think with this crayford.
With mine it seems any pressure whatsoever from the focus lock screw causes loss of about half of the barrel travel. I leave mine totally loose but the danger then is loosing the screw as I almost did on one occasion when it fell out into the grass.
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Aww shucks guys !
