kb244 said:
Out of curiousity, when they went from the F to FT I know they "improved" the shutter, but did they change it to something other than a rotary type?
They all have the same metal rotary focal plane shutter.
I did some digging in old reviews and articles about the FT and found mention of shutter improvements by Jason Schneider in his Modern Photo column "the camera collector" appearing a few years after the Pen F system was discontinued.
Quoting Jason, "...they attacked one of the original F's few defects, occasionally erratic shutter operation, by redesigning the speed-governing mechanism."
Gratifying to our RF interests, he mentioned the compact size and comfortable shape, "...reminiscent of rangefinder Leicas and Canons. It should, therefore, come as no surprise that the Pen F's staunchest devotees are drawn from the ranks of rangefinder enthusiasts."
His article included the same graphic of the viewfinder light path I posted above, yet he still erroneously described a porroprism constructed of mirrors, whereas it actually has one mirror and two prisms. In a segue to mentioning the side-swinging instant return mirror, he also said the focusing screen was placed 45 degrees to the side rather than above. Of course that should be 90 degrees, but it's a fairly easy error to make. Otherwise an interesting retrospective.
A November 1967 Modern Photo Test of the new Pen FT described the new metering system, then listed a few other detail changes from the F. Visible fresnel lens rings in the focusing screen now gone, and the microprism spot added to the center of the larger circle of fine ground glass. Wind lever is longer and of course single stroke rather than double. Self timer added. "The take-up spool is now a quick-loading multiple slot and tooth type. The frame counter has slightly larger numbers..." and M flash sync has been added along with the X.
In a backwards sequence from Pentax experience, the slower normal lenses for the Pen F are better/sharper than the faster ones. Definitely a sacrifice in optimum performance when going from the 38 f1.8 to the 40 f1.4 and especially the 42mm f1.2. They really liked the 38 and 70.
I found a January 1970 Camera 35 test of nine Pen FT lenses where they get confused about angles of view, saying "... this 70mm telephoto ... would be the equivalent of q 140mm lens on a full-frame 35mm camera..." And they make the same kind of error for the 60mm f1.5 ("120mm") and 100mm f3.5 ("...equivalent of a 200mm telephoto..."). Oddly they make no mention of their incorrect 2x focal length "crop factor" with shorter lenses, and even characterize the 20mm as an "ultra-wide", when in fact its angle of view is 73 degrees, placing it about the equivalent of 30mm on a full-frame.
The test shows this 20mm f3.5 and the 25mm f2.8 as both about equally excellent optically.