I just saw the 300 ED cross section on Pentax's German site. It has two ED elements out of nine total. It is a strange design and one in which I feel is not really a telephoto. Yes, it has a telephoto-like focal length but the design is not telephoto. The rear group in the traditional telephoto is afocal and used to magnify the image from the front group and thus allowing for a shorter and lighter lens. Why did Pentax make this lens in this different design? The reason has to do with performance. Any time you use an afocal element or group in the rear of a telephoto it magnifies the aberrations from the front group. Pentax decided not to do this to increase the performance.I sent Pentax an email a while back suggesting they change the 300 to a Plasmat design used in view cameras. I got no response but what they ended up designing was not too unlike what I suggested. ED glass combined with a positive rear triplet on the 300 will make for a sharp lens. If anyone buys one, let us know how it performs.

-- Steve Rasmussen (srasmuss@flash.net), April 27, 2000

Answers

Scott, the new 300mm should be much better than the old design when used with converters. The big difference will be at wide and near wide open apertures. This will be so for two reasons. First, the new 300 won't be magnifying the image with the rear group and second, the use of ED glass will give the new design less spherochromatism and less chance of fringing with a converter. A non-optical advantage of the new design is in the tripod mount on the barrel. The old design used with a converter on a tripod had so much overhang that shutter shake became a major concern.

-- Steve Rasmussen (srasmuss@flash.net), April 29, 2000.

The price for the 300 is in the range of $2000 to $2200(US). I may just trade in my Takumar for the new one. Just wish the 300ED had the f/45 stop like mine. SR

-- Steve Rasmussen (srasmuss@flash.net), April 30, 2000.

Steve,

Thanks for keeping us updated on new and old P 67 lense designs! This is the most informative photo web site I've found.

How might the new 300 ED perform with teleconverters verses a more conventional telephoto design? Sounds like this one could be a real gem of versatility.

-- Scott Seigmund (Ssgmd@aol.com), April 29, 2000.

Does anybody have a price yet? I am REALLY interested...

-- Alex B. (samedobrefotke@hotmail.com), April 30, 2000.

Today I got the listprice in Germany : DM 5500 (1$ = 2.12 DM).

Reinhard

-- Reinhard Becker (reinhard_becker@hotmail.com), May 08, 2000.