On Apr 9, 2011, at 9:18 PM, William Robb wrote: > On 08/04/2011 2:56 PM, Sam L wrote: >> Hi all, >> >> I have a K-x that seems to me to always be just a little soft >> focusing. I'd like to finally get around to testing it a little >> scientifically. To that end I have downloaded the focus charts etc >> from >> http://regex.info/blog/photo-tech/focus-chart >> >> I know I'm supposed to test using the smallest possible depth of >> field. Here are the lenses I can use: >> >> Auto Focus: >> DA40 >> 18-50 Kit >> 50-300 Kit >> >> Is the DA40 adequate for determining the focus accuracy of the AF system? >> >> I also have these MF lenses, but am not sure how to best test out the >> MF focus system (which is a combination of me and the camera). >> SuperTak 50/1.4 >> SuperTak 85/1.9 > > I can't help with the Kx, as I don';t have one, but I would strongly advise > against using any of the focus charts out there in favour of adjusting the > focus against a real world (and real world distance) object. > Unless you are using a flat field lens, (you aren't) a focus chart is > guaranteed to give a false front focus indication.
Why is that? Haven't heard that before. I used a homemade chart to adjust all my lenses at a distance of six to eight feet, checking focus in the center of the lens. Seems to me that would be accurate. But I'm no expert at these things. Paul > > -- > > William Robb > > -- > 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.
