The Pentax A 50mm f2 is the third generation of Pentax’s K mount basic model standard lens and also the last one with a f/2 maximum aperture. The first one is the K 55mm f2 released in 1976 and was later replaced by the lighter and simpler M 50mm f2 introduced in 1979. In 1985, Pentax introduced a newer version (this one) which incorperates electronics to support automatic aperture control for shutter priority and programmed auto-exposures on the A-series (e.g. the Super Program/Super A) and P-series (e.g. the P5/P50) bodies. As far as I have read from the Internet, the A 50mm f2 has the same optical formula as the previous M version but is built with more plastic. Two years later, Pentax released the F 50mm f1.7 as their basic model standard lens to accompany the first Pentax AF SLR, the SFX/SF1.
Optically, the Pentax A 50mm f2 is not really outstanding. In fact, among all the manual focus basic model standard lenses I owned, this one is probably the worst. It lacks behind the Canon FDn 50mm f1.8, the Nikon Series E 50mm f1.8 and the Pentacon Auto 50mm f1.8 MC which rank 1st, 2nd and 3rd respectively. However, this doesn’t mean that this lens is a piece of junk. On the other hand, it is actually pretty usable especially after I deliberately tested for its sharpness and contrast which I do not normally do for a prime.
The following photos are all 100% crops from 2400 dpi scans of Kodak Ektar 100 film (ASA100 color negative). They were cropped off-center about half way to the corner of the frame.
As shown in above, the lens performs best from f/4 to f/8 with f/5.6 being the sweet spot (only very slightly better). It is worth noting the difference between f/8 and f/11 because it will be important for people who shoot with this lens on a sunny day. Now I would set the lens at f/5.6 even I am shooting landscape with a tripod and use f/11 only when I really need the wider depth-of-field. Also, the performance at f/4 did impress me and made me to reconsider to use the Pentax system as a light, carry around, always ready street shooter (I now almost always have the ME Super loaded with ASA400 film plus this lens with me). Finally, let’s see one more sample photo taken with this lens using Ilford HP5+.
Status: In Collection