- Prove that I have understood the basics so far, well enough to be able to make a working simple lens.
- Prove that acrylic can be used as a possible lens element material, and that it can be easily manufactured with modest equipment.
- Create a lens body and mount so the elements can be tested on a DSLR.
- Test the performance of my first lens design, which features no optimization or correction.
- Investigate and create a new optimized lens design using aspherical surfaces to correct image errors.
I had planned to do some more research and be well prepared for my week back in the UK but as it turned out I ended up with absolutely zero time to spare. My French work took over and it wasn't until I was on the plane back home at the end of my first semester last week that I had my first free second, and to be honest I was more interested in sleeping than figuring out new lens designs!
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Anyway, what I had had time to do was order in some supplies. I managed to find myself everything I needed on eBay including a 50mm diameter rod of cast PMMA (clear acrylic), 2x EOS 67mm reverse ring adapters, and an old EOS film body.
I specifically ordered in a larger size rod of PMMA than my design required. This allowed me to adjust my design by increasing the diameter of the element, resulting in an increase of the image space f# from f/1.25 (50mm focal length / 40mm entrance diameter) to f/1 (50mm focal length / 50mm entrance diameter).
The EOS mount I reverse engineered and designed in CAD initially was perfectly suitable to use in this project; however I found it difficult to find aluminium tubing of the required diameter and wall thickness to make it. After assessing my different material options, it turned out to be much cheaper just to buy reverse ring adapters. These adapters are designed to be mounted directly to the body of the camera, exactly as I want my lenses to, and then provide a thread on the adapters front face so that you can screw on a lens in reverse. Each one of these were £3, much cheaper than raw material I would have bought.
The EOS film body was bought just so that I could mount and unmount my lens to something while I was making it to check the fitment. Rather than risk getting dust/grease/general manufacturing crap on the inside of my digital bodies, I thought that an old film body would work just as well. Another advantage was that due to being a 35mm film camera, it features a full frame mirror and view finder, so I could look through the camera and see the full frame field of view.
Overall it was a bit like a second Christmas arriving back home to find all this stuff sitting waiting for me in my room! It put me in a good position to go into school on Monday morning and start manufacturing.
The EOS mount I reverse engineered and designed in CAD initially was perfectly suitable to use in this project; however I found it difficult to find aluminium tubing of the required diameter and wall thickness to make it. After assessing my different material options, it turned out to be much cheaper just to buy reverse ring adapters. These adapters are designed to be mounted directly to the body of the camera, exactly as I want my lenses to, and then provide a thread on the adapters front face so that you can screw on a lens in reverse. Each one of these were £3, much cheaper than raw material I would have bought.
The EOS film body was bought just so that I could mount and unmount my lens to something while I was making it to check the fitment. Rather than risk getting dust/grease/general manufacturing crap on the inside of my digital bodies, I thought that an old film body would work just as well. Another advantage was that due to being a 35mm film camera, it features a full frame mirror and view finder, so I could look through the camera and see the full frame field of view.
Overall it was a bit like a second Christmas arriving back home to find all this stuff sitting waiting for me in my room! It put me in a good position to go into school on Monday morning and start manufacturing.
