Mark Erickson
26-Apr-2004, 10:30
Here's a fun post for the Ektar afficionados among us. I picked up a Kodak Medalist with an Ektar made in 1945. This lens is a Heliar formula 100mm F3.5 and does not have a (L) mark on it. As I understand it, the (L) indicates that a lens was hard-coated on all surfaces using a vacuum process. Prior to this, Kodak lenses were either uncoated or soft-coated on their interior surfaces only. Now, it is possible that Kodak shipped some hard-coated lenses without the (L) mark, but I haven't seen any definitive evidence on the web as to whether or not this happened. In addition, I understand that there were 3rd party companies that hard-coated lenses in the aftermarket.
People talk about identifying coatings from the color and intensity of lens reflections, so I decided to do an experiment and take pictures of lens reflections using a digital camera. I used a halogen desk lamp in a darkened room and took the pictures with a Canon S10 camera with the white balance locked down to daylight and exposure compensation at -2. I took pictures of the above-mentioned 1945 100mm F3.5 Ektar, a 1947 105mm F3.7 Ektar, a 1947 152mm F4.5 Ektar, and a 1952 203mm F7.7 Ektar. The color temperature of the desklamp is definitely on the warm side, but I think that a side-by-side coating comparison can be made from them. The results are summarized in this JPEG image (http://www.westerickson.net/mark/misc/fourektars.jpg).
A couple of things are worth pointing out, I think. When I evaluated the 1945-vintage Ektar, I expected to see two really bright reflections from uncoated outer lens surfaces and a collection of much dimmer reflections from soft-coated inner surfaces. What I saw instead was a complete set of muted, amber-colored reflections. It looks to me as though all surfaces, including the outer ones, have coatings with the same thickness. The 1947-vintage 105mm and 152mm lenses both display similar mixes of purplish and magenta reflections. A real surprise to me was the 1952-vintage 203mm F7.7 lens. I was expecting a mix of purplish and magenta reflections like those of the 1947-vintage lenses. All of its reflections are a complete set of muted, amber-colored reflections much like those on the 1945-vintage lens.
What does it all mean? I don't know. Anyone have any thoughts?
People talk about identifying coatings from the color and intensity of lens reflections, so I decided to do an experiment and take pictures of lens reflections using a digital camera. I used a halogen desk lamp in a darkened room and took the pictures with a Canon S10 camera with the white balance locked down to daylight and exposure compensation at -2. I took pictures of the above-mentioned 1945 100mm F3.5 Ektar, a 1947 105mm F3.7 Ektar, a 1947 152mm F4.5 Ektar, and a 1952 203mm F7.7 Ektar. The color temperature of the desklamp is definitely on the warm side, but I think that a side-by-side coating comparison can be made from them. The results are summarized in this JPEG image (http://www.westerickson.net/mark/misc/fourektars.jpg).
A couple of things are worth pointing out, I think. When I evaluated the 1945-vintage Ektar, I expected to see two really bright reflections from uncoated outer lens surfaces and a collection of much dimmer reflections from soft-coated inner surfaces. What I saw instead was a complete set of muted, amber-colored reflections. It looks to me as though all surfaces, including the outer ones, have coatings with the same thickness. The 1947-vintage 105mm and 152mm lenses both display similar mixes of purplish and magenta reflections. A real surprise to me was the 1952-vintage 203mm F7.7 lens. I was expecting a mix of purplish and magenta reflections like those of the 1947-vintage lenses. All of its reflections are a complete set of muted, amber-colored reflections much like those on the 1945-vintage lens.
What does it all mean? I don't know. Anyone have any thoughts?