Bower ABSPK Pentax K Mount to M42 Screw Mount Adapter

My experience with this adapter was bad. The screw holding the spring clip to the adapter was too long and fouled the threads of my 55 f1.8 Super Takumar lens. It also was an ineffective interface for the auto/man aperture clutch and I permanently bent its actuator pin when applying force to remove the lens from my Pentax K-5. Everything went on easy enough. It was the removal process that ultimately caused the damage to my lens and ruined the anticipation of using such classic glass with a modern camera... All because the only screw on the device was a fraction of a millimeter too long. I read others warnings and thought "surely my experience will be different and fine". It was not. Admit it you are considering this device because it is cheaper than most. Is it worth destroying your fine old lens?

The Bower model screw mount adapter costs more than the cut rate adapters, but has one hard to find feature - It has a small inner ledge that depresses the auto iris pins that are common on Pentax screw mount lenses. Note that there are some Pentax screw mount lenses where this ledge can get in the way - for those few lenses I would recommend getting the model from Pentax.

I did not receive this Bower version. The supplier sent a much cheaper Pentax version. I sent it back for a refund.

Mine had 'Kipon' stamped on it, and it looked/worked just like my other Kipon adpaters. This adapter has the inner flange that will depress the pin on 'automatic' M42 lenses that do not have a manual/auto switch (for example, older Carl Zeiss Jena lenses). Some people glue the pin in place or otherwise modify the lens, but this does the job without making permanent changes. This adapter will allow infinty focusing, although the focusing marks on the lens may not be straight up when the lens is screwed all the way into the adapter. I removed the spring on mine so that I can take it off the camera body without having to unscrew the lens and fiddle with the special tool that comes with the adapter.

This adapter is made for the M42 lenses which have only auto mode of aperture pin. For this purpose, it has an inner flange to hold the aperture pin. However, in the case of my color-ultron 50/1.8 which has the minimum aperture of f16, the aperture pin is pushed not enough. Therefore, though using this adapter, I can use this lens with the aperture range from wide open to f4.0. This adapter is more inexpensive than the similar Japanese adapters, however, please be careful that its height is too high to push the aperture pin completely for some M42 lenses.