Some experimentation – homemade zone plate
I’ve been doing some experiments with a couple of home made zoneplates. For people who haven’t run across these they are an image forming device that works by diffraction rather than refraction (like a conventional lens) and consist of a series of clear circles on a blaack sunstrate. I made mine suing a pattern from here, although there are other resources on the internet. The pattern is printed and then photographed from a predetermined distance to ensure the final size on film is correct as this determines the focal length of the plate. The film needs to be very high resolution and contrast – I used Adox CMS20 microfilm developed in rodinal 1+60. My initial focal length is 48mm for my canon eos dslr, but I think this is slightly long and will make up a roll of shorter focal lengths in a couple of weeks. I also made a 28mm version for the rangefinder.
The zone plate produces a soft focused image of low contrast and with highlights that ‘glow’ into surrounding areas. I am thinking about a series of pictures using the plate. The picture above – which is still waiting on a final title, but to me is about light breaking through from above – was shot and shows the lovely softness and glow.