Hi Dareen, Answers interspersed. On Sep 6, 2014, at 5:05 PM, Darren Addy <[email protected]> wrote:
> I've never messed with the AF Fine Adjustment before, but I think I > need to on the K-3. So those of you that have experience in this > area... > > First, I'm wondering if the procedure is the same on K-3 as it has > been for other Pentax models? If so, I don't need to limit my Googling > to the K-3. It’s basically the same. There may be some slight differences in the menu access, but the nuts and bolts of it are the same. > > Secondly, this works with third party lenses also, right? I've got 3 > Sigma EX to 2 Pentax in the AF department. I don’t know. I don’t own any third party autofocus lenses. But if the camera recognizes them for shake reduction, I would think autofocus adjustment would work as ewll. > > Thirdly, am I correct in thinking that this is of no use on manual focus > glass? You are correct. It merely fine tunes autofocus to eliminate backfocus or frontfocus conditions. > > Fourth, what is your procedure? I'm thinking camera should be locked > down on a tripod and I'm wondering what you use for a target. I've > seen scales (like a tape measure or yardstick) angled at a 45 degree > angle, with a vertical target that is perpendicular to the sensor > plane at the focal point. At what distance do you do the measurement? > Minimum focus distance? Medium focus distance? I'm also guessing you > do this with the lens wide open so as to be able to most accurately > define the in-focus point. What is your procedure on zooms? I use a 13 x 19 sheet of good paper, printed with a scale of lines approximately 3/8-inch apart. The lines cover the middle 2/3 of the sheet, but right in the center there is a blank area of about three inches square. In the center of the blank square is a single red dot of abotut 3/16 inch diameter. This is the focal point. I set the paper on the floor of my deck in bright shade. Then I mount the camera on the tripod. I place the camera about three feet away for a wide lens like the 16-50 and about 7 feet away for a long lens like the 60-250. I use single-point focus with the center dot active. I elevate the tripod head so the camera is looking at the focus dot at an angle of about 45 degrees. I test most lenses in the middle of the focal length range, but check at the wide and long ends as well. Generally, they’re very close. If there’s a discrepancy I’ll favor the focal length I use most. I look at the results on a large monitor and try to judge how many lines on each side of the dot are in focus. The forward lines won’t look the same as the rearward lines even when the focus is about the same. So you’re looking for sharpness. I try to count out which line is definitely out of focus. For example, for the 60-250 at 150mm, it might be line three or four. For the 16-50 at 35mm, it might be line six. Hope this helps. BTW, it’s worth the effort. > > I'll stop with the questions now. Any light that you can shed... > thanks in advance! > > -- > Photographers must learn not to be ashamed to have their photographs > look like photographs. > ~ Alfred Stieglitz > > -- > 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.
