do I need to Micro Adjust my lens?

[weepete]

Hi all,

I was out in my back garden last night trying to take a few shots of the stars for the first time, more as a technical exercise than an effort to produce a good photo. So I set up my camera on high ISO, apeture to f1.8 (was using the nifty fifty) mirror lock up enabled and on a tripod with the 2 second timer as I couldn't find my recent purchace of a cable release and turned my focus ring as far as it would go to get infiniy focus manually. I noticed after a few shots the stars were not the sharp pinhole lights that I've seen from others pics but looked a little blurred, and same problem even when I dropped the ISO and shutter speed. So I found a bright star in the sky, put my camera in live view and zoomed in to see if I could get it any better and sure enough, turning the focus ring back slightly pulled the star into focus.

Is this normal or should I be expecting my lens to focus on infinity when the focus ring is fully turned and should I try a micro adjustment on my camera to fix it?

 

[Derrel]

Well, the lens might focus "past infinity". You do not specify which lens you have...most of Nikon's AF-S lenses (ALL of them, at one time, according to what I read) did not have hard infinity stops, and would in fact, focus past infinity. Also, at f/1.8, the lens very well might suffer from coma, which tend to take point light sources and kind of make them look like,well, like a cat's eye, or like an American football, to use conventional shorthand words. If you have say the Nikon 50/1.8 AF-S G, I would not be surprised if there was a bit better focus using live view.

Micro-adjusting the camera is probably the wrong thing to do.

 

[weepete]

Thanks Derrel. It's the Canon EF 50mm 1.8 I was using and I've not had any other focus issues with it but it definatley seems to be focusing past infinity. I'd never heard of infinity stops before but I think your right and doubt ithas them. Thanks for the advice!