In April there was a great full moon and I went out to the Charles River to photograph the city with the moon overhead. I had just realized how nice a lens I got with my K1000 when I bought it from eBay. It’s a 135mm f/2.5 and if you look down the barrel it’s all glass – beautiful.
Anyway, apart from my 50mm f/2.0, this is my fastest lens. The zoom lenses I got with my K10D start at f/3.5 or something. Since it was dark and I wanted to keep the exposures as short as possible, I thought I’d use my 135mm.
Unfortunately, when I took some pictures with it, I got the image below and others like it:
The moon shows up twice and the word “Prudential” is also visible twice. From the word “Prudential” it’s clear that this secondary image is upside down and backwards with respect to the original.
Initially, I didn’t know what was going on. At some point, however, I thought it might be related to the UV filter I had on my lens. I took the UV filter off the lens and the weird reflections disappeared. This solved the problem but it still doesn’t explain to me why or how this happened. I can’t think of a physical explanation for what I observed.
If anyone knows what set of reflections could be responsible for upside down and backwards “ghost” images appearing, please let me know.
