The Normal Lens

Week 12

The 50mm prime lens, also known as a standard lens or normal lens, came on a lot of 35mm cameras and was mounted on the first Leica that made 35mm popular.

I have several 50mm lenses for my Nikons, both manual and auto focus. They are nice because they are small, have low distortion, usually are very sharp, and are fast - down to f/1.4 or even f/1.2. Even the slowest ones are faster than the amateur zooms that come on most cameras today. Here is a shot taken at night in very low light with Nikon's cheapest current lens - a 50mm f/1.8 autofocus. I had to pan to keep the boat sharp but it shows what is possible.

Why is a 50mm lens considered normal? Actually there is a range that fits in this category and it varies according to film or sensor size. Typically normal perspective as perceived by humans is taken to be equal to the diagonal distance of the frame. For a 35mm frame the actual dimensions are 24mm x 36mm so the diagonal is 43.2mm if I have done my math right. That means a 50mm is actually a slight telephoto in the 35mm format.

Older rangefinders often came with a lens around 42mm to 45mm in focal length, including the camera I used to take this picture - a Kodak Signet 35 from the early 1950's. This is closer to an ideal normal perspective, at least according to the mathematical definition I've used above.

Back to the photograph. It was taken in a hotel room as we were waiting to move into our apartment. I took it because of the quality of the filtered light coming through a large window on the left side of the frame and it gave me a chance to test the lens wide open (in this case only f/3.5). I thought it would probably be a bit dreamy and not too sharp given the age of the lens but actually it is pretty sharp. Film is modern Kodak 200 bought in a drug store.

It is a bit overexposed and not on purpose. I determined exposure by taking a snap with my Nikon D3 which came up with f/3.5 and 1/15 at ISO 200. The Signet 35 doesn't have 1/15 but there is a 1/25 shutter speed so that is where it was set for this hand held picture. So why is a faster shutter speed overexposed? Probably because the shutter needs adjusting after all these years.

There is very little post processing in the picture. I straightened it a bit and took some shine out of the framed picture on the wall using the cloning tool. I like the way the out of focus areas look but can't tell how much of that comes from the film, the camera and lens, or the relatively low resolution scan. The D3 is quite a bit sharper and of course exposure is "better" but I like the Signet 35 look.

Idea based on Standard Bearer, pages 120-121 in the book 50 Photo Projects, by Lee Frost