After taking a few photos last week with my Mamiya 645, I found on examining the negatives that after using the focus collar to set hyperfocal distance with infinity aligned to a stop more open than I was using, distant objects were still quite soft. That led to testing my four lenses yesterday with results today.
Let me say that I am well aware that lens scales are optimistic, based on minimal enlargement, and may be variably accurate as to distance indication.
With tripod solid, mirror lock-up, and 1/250 or 1/500, I took in a scene with signs at varying distances and a road and trees perhaps quarter-mile distant. For each of my three most used lenses, I made four exposures: 2 at f16 and 2 at f/11, the first two with infinity aligned with 11 and then 8, the next two at 8 and then 5.6, thus doing in a different way what those who know do, i.e., closing down 1-2 stops after using whatever guide for DOF. The guides, including the lens scales, are based on minimal enlargement to render apparent adequate sharpness of DOF at the boundaries. My lenses are all Mamiya.
My 80 appears good, in that Inf looks respectably sharp even with an extra 1 stop "leeway." The 55 and 110 do not look sharp at Inf even with 2 stops "surplus", though they are very sharp in the nearer distances. I also tested the 55, the 110, and my 150 for infinity when actually focused on Inf. In each case objects at Inf look sharp and well-defined.
I checked my lenses scales against an online DOF calculator that uses d/1500 for CoC. At f/16, the hyperfocal distance (H) for the 55 is 14'. At f/8, my scale put H at about 17-18 ft, so at least that neg should be sharp. H for the 100 at f/16 on the calc is 55'; on my lens at f/8, it's maybe 70'.
I don't know enough about optics to judge these results. So, I am wondering whether the 55 and 110 (which was recently serviced by itself by a reputable place) need to be calibrated on camera for mount adjustment, or what.
Let me say that I am well aware that lens scales are optimistic, based on minimal enlargement, and may be variably accurate as to distance indication.
With tripod solid, mirror lock-up, and 1/250 or 1/500, I took in a scene with signs at varying distances and a road and trees perhaps quarter-mile distant. For each of my three most used lenses, I made four exposures: 2 at f16 and 2 at f/11, the first two with infinity aligned with 11 and then 8, the next two at 8 and then 5.6, thus doing in a different way what those who know do, i.e., closing down 1-2 stops after using whatever guide for DOF. The guides, including the lens scales, are based on minimal enlargement to render apparent adequate sharpness of DOF at the boundaries. My lenses are all Mamiya.
My 80 appears good, in that Inf looks respectably sharp even with an extra 1 stop "leeway." The 55 and 110 do not look sharp at Inf even with 2 stops "surplus", though they are very sharp in the nearer distances. I also tested the 55, the 110, and my 150 for infinity when actually focused on Inf. In each case objects at Inf look sharp and well-defined.
I checked my lenses scales against an online DOF calculator that uses d/1500 for CoC. At f/16, the hyperfocal distance (H) for the 55 is 14'. At f/8, my scale put H at about 17-18 ft, so at least that neg should be sharp. H for the 100 at f/16 on the calc is 55'; on my lens at f/8, it's maybe 70'.
I don't know enough about optics to judge these results. So, I am wondering whether the 55 and 110 (which was recently serviced by itself by a reputable place) need to be calibrated on camera for mount adjustment, or what.