Zeiss Ikon Nettax – photos
I was very pleased with the performance of the uncoated Tessar. There is an aging process that sometimes occurs with older uncoated lenses. It's known as blooming and results in an iridescent color over the surface of the lens.
Some have compared it with lens coating and say that such a lens that exhibits this can be as effective as a coated lens. In any case, these shots were helped by the overcast weather on some days. However, the Tessar was able to handle a high-contrast situation very nicely.
The performance of the Tessar is very typical of this lens. From f/2.8 to f/5.6, when focusing at objects that are roughly 4 to 10 feet from the camera, the backgrounds are rendered with a definite roundness to them (see No. 1 and No. 3 on the first row). Once you've closed the lens to f/8 or smaller, things smooth out, which you can see in No. 3 in the second row.
The Tessar is capable of recording very fine detail. The determining factor on many uncoated lenses is its physical condition, especially the presence of cleaning marks. Most older lenses have them. With this camera, there were very few cleaning marks, so contrast isn't affected much, if at all.
I suspect this lens would flare quite easily, because the front element sits very close to the face of the bezel. I have tried to keep this in mind when I'm out with the camera and have repositioned myself when possible to avoid the sun from striking the lens at an oblique angle.