I was looking for a lens for my Pentax K100D and decided to go for the FA 50 1.7 version. People told me the 1.4 version was better but i found the 1.7 for a great price new. This lens when used on a DX format camera will give a field of view equivilent to 70mm if compared to SLR film days. This is due to the crop factor regarding the sensor on the DSLR. The lens is fairly sharp when used at the widest aperture of 1.7 and gets sharper as you close the aperture a few stops. It renders very nice out of focus areas and this was great for portrait work so that you can make your subject stand out. On a trip to Venice i got some wonderful low light pics using this lens. The fast aperture combined with the shake reduction in the camera allowed for very low shutter speeds hand held. The lens is small and light and takes up no space in a camera bag. Hard to come by now so will never sell mine that is for sure!