I have a soft spot for less than perfect optics. If you've seen pictures from The Plank on these pages, you might know what I mean...
Lenses such as this should never be considered if the ultimate in imaging performance is important to you. In fact, many people will find images such as this one quite distressing.
All lenses have individual signatures, the best ones tend to have less identifiable ones.
A Petzval projects a very sharp image in the centre area, and the lens was designed to make use of that area only, but modern photographers sometimes like to show the results of the aberrations at the edges. Tessars have a larger usable circle, and the circle of illumination is much larger still, but resolution drops off quite rapidly beyond that and this effect can be used sympathetically on some images. Sometimes, the part of the image that you're pushing beyond the limits might not have resolvable detail anyway, areas such as blank skies, for example, but the vignette, whether dark, light, or blur, is a pictorial tool which can be used, or abused.
I've been meaning to try this one for a while- I have a little soft focus lens, a Rodenstock Imagon, 200mm, a single group achromat that goes in the back of a Copal 3 shutter- I use it in the shutter for the Nikkor 450 M, a Tessar, which is anything but soft focus. Of course I was tempted to see what the image would be like when the front element of the Nikkor was combined with the Imagon in the rear...
So it turns out that it produces a lens which is around 11" focal length, at around a stop faster than the Nikon, f/5.6. It doesn't cover anything, if coverage is defined by an area of acceptable resolution, but it lights up an area somewhat larger than 8x10.
The Imagon achieves its soft focus effect through the controlled use of spherical aberration, controlled if you use the tea strainer disks on the front of the shutter, that is. Adding the Nikkor to the front induces a huge amount of coma.
When I first saw this negative, it looked a bit like it looks here- a mush. I scanned it at low resolution, thinking that there'd be nothing to see- but I was wrong. Although I might have been expecting to find a soft focus landscape lens, it turns out that the only thing that's really sharp are the coma effects. Defects. I don't need to describe it, you can see the effects in the details above.
Of course, this was just an experiment, I made this picture while I was making another video about the camera, one that I deleted in its entirety, so the spot was chosen to give me space to work, not necessarily for its pictorial qualities. The sun was shining directly on the lens, just out of frame, and I had forgotten to shade it, so I fully expected the picture to be dominated by flare anyway.
The next step will be to make a print of sufficient scale so the aberrations become the picture. Perhaps there's another picture to be made on this lens sometime...