Wow!
It's been a while since I last made something so extreme!
Not that there are many parts in this one. But it's more about how much it cost me to build and how hard it was!
Thing is, I had to literally buy everything for this build, so the cost has shot up to around 40$... very little recycling in this one. Also, I hadn't thought about how hard steel really was until I started cutting away with the reciprocating saw... I can almost still feel the vibrations in my arms
But first, a bit of history on the project:
I've always wanted to have a lens I could use handmade optics on it.
Problem is, I could never find a suitable piece of optics that I could tear down for the project.
Then came Ed with his hand made Bronny lens... and I just had to have one.
But since I always seem to over-complicate projects, I thought it would be neat to have an helical focusing mount to help with focus. So, after a stop at the astronomy store for a T-mount, I took a trip to my junk bin to find a lens. I stumbled on this pair of plastic kids binoculars from the dollar store. Nice lens with a strange blue tint... why not?
So I took out the lens and eyeballed the focusing distance for infinity. Lensless camera to my eye, I was hand holding the lens at infinity while my mom was measuring the lens to camera distance. Now, I knew what length of tubing was needed. Next stop, the biggest hardware store in the region. I found some pipe nipples of the proper diameter for both the internal tube and the external focusing mount. They were far from a tight fit but what the heck, I can always pad the inside with something. Last thing was I needed a front screw in ring to hold the lens in. Plumbing section to the rescue again!
So, I had most of the parts. I measured everything carefully, and began removing some excess metal. First, the internal tube got cut at both ends. Then, one of the threads of the focusing part was removed. I re-measured everything and using a strip of paper, I laid down the marking for the focus helix. To keep some structural strength, it takes only 2/3 of a rotation to go from infinity to close-up. Then, came the drilling, cutting, filing, testing, swearing, re-filing...
To make both tubes fit more snugly together, I used some plastic from a yogurt container. The inside of the helix side is protected from light using a piece of thin cardboard. The whole focus mechanism uses a steel pin to stay in register.
The lens is mounted on a piece of sample laminate flooring with a ton of hot glue on the back. And it is all held with a threaded PVC tube.
Now, for a bit of detail:
Focal length: 139mm
Lens diameter: 27mm
F/stop: f/5.1
Focus: 3 feet to infinity
Weight: 1 lbs 11.1 oz (or 768 grams)
I decided to call it the 139mm F5.1 Chromagon HM for a few reasons:
1. it's not an achromat or an apochromatic lens
2. it's primitive so chromagon plays nicely with cro-magnon
and the letters HM... they obviously stand for Heavy Metal
Here are a few pictures of the project itself. The sample shots are yet to come.
