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You have an interesting experience using optics. I am also experimenting with lenses for slide projectors. There are interesting opportunities here :-)

@bambuka, How nice to know that, I would like to see the result of your experimentation it would be very interesting to see the device... what I show in the publication is armed with plastic objects what I picked up from a beach like some oil caps and cylindrical objects... I am preparing a publication on Macro photography with a very old cell phone and a magnifying glass called thread count. It will be my next publication the results are very interesting!

Before these macro devices for the phone existed, I was already taking great photos of insects and flowers. You will like the results!

while I made one full lens. It can change the focal length and it has an aperture. All this is assembled from a plastic pipe and parts of other lenses. I used to do a post on this topic. I think we need to make fresh photos))
It will be interesting to see your results.