Wallace Koopmans Artlog

In the image above the lenses on the right side are all homebrew lenses I made for the Pentax Q.  I purchased three Q mount to C mount adapters, took them apart and used only the part that mounts to the camera.  The lenses themselves are a 12mm pancake distortion creator a 35mm f2.8 and the newest one a 40mm f1.9 from a Canon AF35ML which is currently set to a fixed focus point and aperture and works like a macro lens.  They are of course manual focus and with the conversion factor the 40mm has a field of view similar to a 220mm lens on a ‘full frame’ sensor or 35mm film.  Each one of these lenses has limitations in the quality of the image they produce but are a fun way of experimenting.

Pentax has released a new firmware update for the Q     PENTAX Firmware Update Software for Q    which dramatically improves the autofocus, especially in low light.  It wasn’t that the Q was bad before but there is a noticeable speed increase.  At the moment though the only lens I own with autofocus is the standard prime.  A quick test in very low light shows that the camera is able to focus at 3200 ISO f1.9 and 1/4sec which is about -1EV which is very good and approaching DSLR levels.

I often take the Pentax Q with me when I’m out simply because it outperforms its size.  What I mean by that is for the small amount of space it takes up it exceeds any other camera I have.  It can be jammed into a jacket pocket or worn around the neck either way it’s hardly noticeable.  As for wearing it that’s something that gets little mention, most cameras its size don’t have a neck strap and I prefer to wear cameras that way rather than with a wrist strap.  This gallery of images from the last two weeks were taken with the 01 prime lens the 03 Fish Eye and my Homebrew 40mm.

I chose this lens from my parts bin because it was a complete package including a helical focus system, unfortunately I don’t know what camera it came off but it appears to be a 40mm f2.8. That 40mm when converted to a full frame equivelent is 220mm.  Once I figured out the distance it needed to be placed from the sensor I mounted it on the end of a piece of ABS tubing which also attached to a modified Q to C-mount adapter I had purchased on the internet.  Initial testing was done with no aperture, it was wide open.  The resulting images were soft and lacked contrast as you can see with these following images.

My next step was to line the inside of the lens with black velvet paper to keep down the internal reflections and create a fixed aperture to try to improve the lens performance.  These changes had a dramatic impact on image quality.

But I wasn’t quite done.  I made a new aperture that was a bit smaller and did some more testing.  This is the state that it is at right now.

I was likely 100 feet away from the rebar in the one picture and you can see that the bridge, hundreds more feet away, was also in focus.  That isn’t always a desirable quality especially if you want to use selective focus to separate different planes in an image but on the other hand this is a feat you can’t easily accomplish with a large sensor camera if it is what you want. And the lens is very small I might add.

A final note here is a comparison 100% crop from the Nikon P7000 at full zoom (200mm equivalent) vs the Q homebrew (220mm equivelent).  The Q is on the left.