Many thanks for the kind comments everyone.
Paul I had to smile at your comment about 'mastering' the focus. Truth is that I have the lens taped down (and also marked with a metallic pen on the lens barrel) at where I determined the point of focus was & just use that setting on each imaging run (that kinda makes me seem like a bit of a slob, methinks)!
On the question of globulars I think that because M13 is widely regarded as the 'showpiece' glob for us northerners, seeing/imaging some of the lesser known ones such as M3 & M92 becomes far more appealing to some of us. There is one cluster (an open one this time as opposed to a globular) which I would love to get this season before it disappears into the evening twilight. That is M41 - a bit of a challenge for us in the UK due to its southerly declination.
Brian, I bought this lens, second hand, in 1986 when I was heavily into daytime SLR photography. In fact the case which I subsequently bought to house it in was more expensive that the lens itself! Up to now I've only used it on odd occasions for astro imaging, partly because its fastest speed is only f/8. I was very pleasantly surprised at the sharpness of these images which has made me look at this lens in a new light! Another thing that I like about it is that the barrel unscrews which allows me to fit one of my 52mm light pollution filters in place with a couple of pieces of masking tape!
