On Thu, Oct 20, 2011 at 1:13 PM, P. J. Alling <[email protected]> wrote:
> Tim, think about what you just said. The stars are as close to infinity > focus as anything you'll ever look at. I think you meant me, not Tim. Neither the mechanical stop, nor the infinity marking, on a lens is accurate enough for precisely focusing at infinity for astrophotography. There's usually some slop to let the lens focus "past" infinity due to mechanical tolerances and/or thermal expansion of the lens. Or because they hire Buzz Lightyear as the lens designer. > > On 10/20/2011 8:10 AM, Matthew Hunt wrote: >> >> On Thu, Oct 20, 2011 at 2:21 AM, Larry Colen<[email protected]> wrote: >> >>> http://www.flickriver.com/photos/ellarsee/sets/72157627935602764/ >>> >>> Each was shot at a different combination of ISO, shutter speed and >>> aperture, varying from ISO 1600 to ISO 100. >>> >>> One thing that I learned is that I'm going to need to go out during the >>> day, focus my lenses on infinity and mark exactly where that is. >> >> How did you focus these? I would guess that Live View would be the way to >> go. >> >> The star trails look pretty well controlled at 80 seconds in these shots. >> >> For fun, you might try uploading to nova.astrometry.net, the blind >> astrometry solver, which will identify objects in your image. Or you >> can add to their Flickr group: >> >> http://www.flickr.com/groups/astrometry >> >> Thanks for posting these. I was looking forward to seeing some examples. >> > > > -- > Don't lose heart! They might want to cut it out, and they'll want to avoid > a lengthily search. > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
