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In the course of searching for a reasonably priced used lens for an 8x10, I came across a 305 6.3 Caltar-Ilex. Can Anybody tell me a little more about this mode ls pedigree, image circle and other specs. These days the Caltars come from eith er Rodenstock or Schneider. This one looks suspiciously like a Commercial Ektar. It's in mint condition and priced at 300 dollars. So if it is an Ektar, it's a bargain. I'm looking to use it, not collect it, so the brand name means nothing.
Marshall: I believe it is an Ilex made Caltar, which as you have figured out, is based on the Tessar formula as is the Commercial Ektar. It is an excellent lens for general photography with 8x10. Sounds like a good price if the lens and shutter are in good condition.
Regards,
Marshall,
Yes, it's a 4/3 Tessar, essentially a copy of the Kodak Ektar, made by the Ilex Optical Company and sold by Calumet, Burke & James (as the Acutar), and others. This particular design dates from c. 1964 and is single coated. The image circle was specified as 325mm at f/22. It's a decent performer; I owned one for several years before I replaced it with a Fujinon 300mm f/5.6 W (a 6/4 plasmat), which is noticeably sharper out toward the edges of the image, but also cost twice as much. $300.00 for a clean 305mm Ilex is a fair price. Make sure the shutter (also an Ilex) is working properly. These are not the greatest shutters in the world.
James Meckley
>> The image circle was specified as 325mm at f/22.<<
Is this a little small for 8x10, and does it increase at smaller apertures?
Marchall: Tessar formulas have great images at center, which deteriorate substantially at about 50% from the image circle. In 4X5 that is not much of a problem. If you want maximum corner to corner sharpness on 8X10, there are better optics available, though bigger and heavier. Also, most old lenses may not be multicoated.
>>Tessar formulas have great images at center, which deteriorate substantially at about 50% from the image circle
Julio:
Yeah, but doesn't this even out as one stops down? I gather getting edge-to-edge sharpness with older (non plasmat) lenses depends on finding that perfect balance between coverage, edge-correction and difraction. Or have I gotten it wrong?