wslam Posted December 3, 2009 Share #1 Posted December 3, 2009 Advertisement (gone after registration) Since my 75 Cron ASPH seems to be way off when I focus at its closest focusing distance, I decided to my other lenses: 35, 50 Summicrons, and a 50 Noct 0.95. I didn't bother with a TriElmar (16-18-21) since there's just too much DOF... Here is the result: Full size (100% crops) can be downloaded here. The 35, 50, and 75 Cron focused on the 4ft mark. The 50 Noct focused on the 3ft mark. Now, it looks like my 50 Cron and 50 Noct are perfect, but my 35 Cron is back focusing a little, while the 75 Cron is seriously front focused. Is it safe to conclude that it is the lens that need calibration and not the M9 body? Thank you. Trying to decide what to bring to fix... ws Link to post Share on other sites More sharing options...
Advertisement Posted December 3, 2009 Posted December 3, 2009 Hi wslam, Take a look here Focus Check. (please help). I'm sure you'll find what you were looking for!
lars_bergquist Posted December 3, 2009 Share #2 Posted December 3, 2009 Your 75 is not back-focusing, it's front-focusing. The old man from the Brass Age Link to post Share on other sites More sharing options...
wslam Posted December 3, 2009 Author Share #3 Posted December 3, 2009 Your 75 is not back-focusing, it's front-focusing. The old man from the Brass Age Thanks. Sorry... late here, all confused. I have edited my post. ws Link to post Share on other sites More sharing options...
jaapv Posted December 3, 2009 Share #4 Posted December 3, 2009 Yes - just send the Summicron 75 in. Link to post Share on other sites More sharing options...
UliWer Posted December 3, 2009 Share #5 Posted December 3, 2009 Before sending the 75-cron in, you should do more testing. When I had the lens at first I thought it was back-focusing; in other tests I found it front-focussing. Then I used the 1.4x-magnifier and tried to be very exact, especially by avoiding the bifocal glasses I use for reading: and it was spot on. This lens is not easy to focus, especially on short distances; if you move the focussing ring just a fraction of a millimeter you get big differences. Link to post Share on other sites More sharing options...
scsambrook Posted December 4, 2009 Share #6 Posted December 4, 2009 I don't have the M9 but thought I had a problem with my M8 and my old Tele Elmarit which I've had for years and which always seemed to work fine on my M2. UliWer is absolutely correct - even small errors in lining up the r/f images can make a big difference especially at close ranges. After doing lots of 'tape measure' shots I'm convinced that i) my Tele Elmarit IS fine and ii) it's VERY easy to mis-align in the viewfinder. It's interesting that I can actually get a higher success rate at wide apertures and ranges between three and five feet with my 90mm Tamron on my Pentax K10d. After that the M8 wins every time! Your 75mm might indeed have a fault, but I nearly sent my lens and body off for adjustment before deciding to do some 'serious' tests. Saved myself some time and postal costs! Link to post Share on other sites More sharing options...
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