My M42 adaptor from Fotodiox arrived this morning so I got to play with my just purchased Pentax Super-Takumar 50mm/1.4, which I got in great shape for $45.
I did a quick test with window light only on a cloudy Seattle day. Camera is a Canon 5D at ASA 100.
I shot three pics: wide open at 1.4, at 2.8 and 8.0. I did no curves or other adjustments. I resampled the three images down and flattened the document for the web. I used a slight amount of Unsharp Mask at 86% for the final flat file.
I like the look, its "mellower" than my Canons but with lots of sharp detail. Informal survey from my wife indicates that we both like the dreamy look of the first shot, wide open at 1.4. Look forward to trying this lens out with some portraits.