By Georg Wacker
5 Oct 2008
After several reincarnations of bodies and kits we arrived at the Pentax KAF3 mount with SDM (as in ultrasonic speed). Remembering the old days with my Minolta it is pretty slick to work with a current kitlens already. Being on the low budget side as a student won't allow me to use any of those fancy SDM-powered lenses soon, though.
So after spending some time with the kitlens (K200D with 18-55AL II) I wanted to extend my possibilities anyhow. This is where the KAF mount system plays its real advantage: backwards compatibility.
Any of the K-mount lenses that were produced in the last 30 years will work with my camera.
I stumbled across the SMC Pentax-M f/1.7 50mm prime lens at ebay and read some very promising lens reviews about it. Being lucky, I got it for about 30EUR ($40).
The build quality of this lens is astonishing, full metal and a nice rubber ring for focusing. In comparison to the 18-55AL II, focusing requires much more grip but goes smoothly. Once set, it will stay put.
The metal ring for the aperture goes from 1.7 to 22 and snaps nicely. The overall feel is superb, it almost feels 'wrong' to equipp the plastic kitlens again.
By using the green button in manual mode (K200D), one can trigger the metering to get a compiled shutter speed. But that's how automatic it will get with this lens. I find the metering a bit off sometimes, it gives a good clue for the current light situation but an external light meter would be better.
When enabled, the AF can act as a focus helper, but most times I trust my eyes. If the light situation is difficult I would always make several shots with little adjustments to the focus ring.
Once set correctly, the sharpness really is amazing. The bokeh is also nice and creamy, but sometimes a bit harsh on articulated lights (see image #5 in the top left corner).
With a crop factor of 1.5x this lens works as a 75mm, not a classic portrait lens anymore but especially usefull in dim light situations with its f/1.7 aperture.
The build quality of the Pentax-M series is top-notch and I hope to extend my lens range with a macro version soon. For just $40 at ebay this is one of the best lenses you can get for this money.