Tuesday, 1 June 2010

Magic Lantern / Petzval Lens

I’ve recently acquired a couple of 19th Century Magic Lantern lenses and I was really looking forward to do this test.
Magic Lanterns were the predecessors of slide projectors and the page below it's a great source of information:

I mounted one of the lens in a piece of cardboard and put in my 4x5 Toyo camera. For this particular test I was trying to get the exposure time correct as most of Magic Lantern lens haven’t got an aperture setting to control the light.

A bit of resource and  I found out that the focal length is 195mm and the aperture is about 4.5, for this reason a low speed film (25 ISO) it’s definitely something to consider.

I used 100 ISO roll film (because I couldn’t wait until I get some 4x5 25 ISO!). This is a cheaper alternative but I won’t be able to see the lens effect in full, but since I’m more interesting in the exposure times for now it’s fine.

The film is Fuji Across 100 and I processed in Rodinal 1:100 solution.

The results came out slightly darker than I wanted, the exposure time was about 1 and 2 seconds and considering I'm using 100 ISO and a lens cap as a shutter it's not that bad. It will definitely improve when I buy a 25 ISO and with a 4x5 negative I'll also be able to see more of the lens effect, they're known for giving a sharp image in the midle and quite a lot distortions around the edges.