Click HERE to read Part I if you're lost...
For a little scale as to what 1000mm looks like, here is the test scene through a 50mm lens on a full-frame camera (D700). The turquoise box is the field of view of the 1000mm lens.
For fun, I threw in a crop from the key image made with the Nikon 50mm f/1.4 at 100%. Due to posting size restrictions, for the time being, I have posted the Century results at full-frame in a reduced size. Full size from the D700 is 4256 x 2832 pixels.
Nikon 50mm f/1.4 AF-D
The Century Tele-Athenar 1000mm f/5.6 does not perform extravagantly wide open. In it's defense, most lenses do not. I do not know what kind of specs were required of this lens when it was designed but it appears it will have to be stopped down to be used for anything more than an enormous spotting scope.
Chromatic Aberration - In high contrast situations, this lens definitely exhibits some serious CA.
Vignetting - Clearly on a full-frame DSLR, the Tele-Athenar 1000/5.6 has some severe vignetting wide open and diminishes as stopped down but is present all the way through f/64.
Sharpness - This lens resolves quite well especially considering that at 1000mm many more factors come into play than at say 300mm such as weather, temperature, atmosphere, etc. Wide open the lens is soft but f/8 isn't too bad and f/11 is great. I think optimal aperture is actually around f/16 or f/22 with this lens.
Distortion - I don't see any noticeably severe distortion.
Contrast - The sample images have been aided by a slight curve in post process. The lens appears to produce good contrasty images but not as contrasty as my *ED Nikon glass. Also flare may have been a factor given the extremely bright day.
Flare - I used this on an overcast day and achieved some very nice, contrasty images. However, in this test on a very bright, sunny day, the lens produced slightly less contrasty images. The lens possesses an ample hood for protection against stray rays so this may have been due to atmospheric conditions.
Color - Images seemed to come out a bit dull in color. No especially beautiful rendering.
Bokeh - Possibly due to the number of aperture blades, along with the immense focal length, one can achieve some beautifully soft bokeh with this optic. I will work at getting some samples of this soon!
The Century Tele-Athenar 1000mm f/5.6 is hardly a practical lens. At best it's a novelty, if not simply an anchor. I love it nonetheless. I suppose it's more for the pure shock factor of putting this on a tripod and pretending to be serious. The lens is capable of some very sharp images at smaller apertures.
It probably would make no sense to make a recommendation here, seeing as few will ever come across one of these. But in the off-chance you do find one, above provides a good sample of what you can expect and make your offer accordingly. I had a hawk flying overhead and attempted to "bird" with this lens. HA! That was a challenge!
Next stop with this lens? The Moon!...on the GF1...with some TCs