I've been looking for a good and inexpensive 25mm lens to use as a daily-driver on my E-P2. All of my current lenses are for the M42 mount. My 25mm lenses are a Vivitar pyramid, which is too large for putting my camera in a cargo pocket, and a Soligor which is hazy. I've looked into native options, and am now looking at c-mount lenses. According to this fancy-pants spreadsheet a 21mm image circle would be necessary to cover a 4/3 sensor. If I'm understanding this right, it makes sense, as that is, by definition, what 4/3 means. It has been discussed that the infamous Noktor lenses are Goyo 0.95 lenses with fancy mounts. According to Goyo's spec sheet, their 0.95 lens has a 1" image circle which would make it a 17mm diameter according to wikipedia and that fancy spreadsheet says it wouldn't work. So...is Noktor doing anything else fancy to make that work? Are there any other, similar 25mm lenses which would make me happy? It looks like Goyo has some 4/3 lenses, but only go down to f2. That is faster than either of the lenses I currently have, though.