Lens and Blackout technique
Initial research into the use of lenses to improve the quality of my projections was not being very fruitful. While Camera Obscura artists (on my radar) all said that they used lenses, there was scant information as to what lenses they actually use, and how. You tube videos that I watched seemed to settle for a plastic torch lens or (in the case of constructing Pinhole cameras) magnifying lenses. However, I did come across an article (from Peta Pixel) that talked about a product from Bonfoton that was specifically designed to turn rooms into Camera Obscuras. https://petapixel.com/2017/07/19/bonfoton-lens-helps-turn-room-giant-camera-obscura/ 31.03.18.
I did a little research on the company and the product and they claimed that their lens was the only lens of the market specifically designed for this purpose. The company itself seemed to be a small start-up concern, and for (around) 27€ they would send me the lens from Finland. I was a little wary about the quality of the product but decided that at 27€ it was worth a punt, and so ordered the item online.
Screen shot taken from the Bonfoton website - 31.03.18
Screen shot taken from the Bonfoton website - 31.03.18
The lens arrived through the post within a few days and initial concerns regarding quality were put aside as the product seemed to be well put together, and presented very well.
The Bonfoton lens out of the bag. The kit comprised of the lens, a cover for the lens, a sticker/cut out template for the aperture, and full instructions for both preparing the room and use of the lens. All this came in a little bag to keep it all together.
The Bonfoton lens itself is of a good solid construction. The cover is held in place with magnets (as can be seen) and there is an option to use magnets (fitted on the rear of the lens) for mounting the lens itself.
The instructions that came with the lens suggested that aluminium (tin) foil could be used to easily and quickly blackout the windows in a room.
The technique for this involved spraying a liberal amount of water onto the window that was to be blacked out, and to lay a sheet of foil over the spray.
The ‘Tin Foil’ technique worked very well in tests. It was recommended that the foil was left in place for no more than 48 hours as there was a potential for the glass to be stained if the water dried out to much, but the technique was quick and effective. It also solved the ‘double layer’ problem that I had been having with the blackout material (I had been losing light in the gap between the layers) as the foil blacked out the room in a single layer. I was now a slave to the weather and needed a good sunny day to put the blackout technique, and the lens to the test, and to see if the lens would truly give me the sharp projection that I was looking for.