I just saw an advertisement for this new lens from Smile Photo(USA). It is listed for $2160 but given the history of this photo store, it is doubtful that the lens can be had for less than $2500. Anyway, it is priced lower than I was expecting. I'm sure the ED won't color fringe wide open, but then again, the 300 Takumar didn't either. SR

-- Steve Rasmussen (srasmuss@flash.net), April 03, 2000

Answers

It is no surprise that the 300 Takumar will fringe wide open with the 2x extender because the effective focal length is now 600mm. Neither the lens nor the extender is corrected for more than three colors, so there is bound to be some tertiary spectrum when the two are combined. My guess as far as the fringing colors; green and/or violet. The 300 Takumar/Pentax(non-ED)seem to be corrected for color about like Canon's FD 300mm f/4 L. SR

-- Steve Rasmussen (srasmuss@flash.net), April 05, 2000.

For me, the biggest advantage of the new 300mm ED is not the glass but the fact that the lens has a tripod mount!

-- Steve Rasmussen (srasmuss@flash.net), April 09, 2000.

I feel Pentax is playing follow the leader somewhat with their new 300mm being ED. Here's why: Wide angle and normal lenses need a small degree of color correction, which is much less than the telephotos. Wide angles and normals will not color fringe when corrected for two colors(achromatic). There is just not enough distance for the uncorrected colors to separate. The longer the focal length, the more color correction becomes necessary. The difference in correction between a 300mm and 800mm is huge. If an 800 were corrected to the same degree as a 300 that had no fringing, the 800 would fringe so bad that it would not be shootable. The old five element Takumar/Pentax 300mm is the shortest focal length of the Pentax line to correct for three colors. It makes sense that it will not color fringe. For Pentax to make this lens an ED is more of a "Follow the Industry" move than smart optical design. Using ED glass in the 800mm was a good move however because of the difficulty in controling the uncorrected colors at that focal length. The 600mm f/4 should be redesigned with ED glass or be superAPO(5 colors corrected). SR

-- Steve Rasmussen (srasmuss@flash.net), April 15, 2000.

>> I'm sure the ED won't color fringe wide open, but then again, the 300 Takumar didn't either.

I have the 300 Takumar and I have noticed that it does fringe even stopped down when used with the Pentax 2X tele-extender. It's hard to see on a transparency without a powerful loupe, but the fringes are 8- 10 pixels wide at the edges of the frame when scanned at 3200dpi.

Jonathan Sachs Digital Light & Color

-- Jonathan Sachs (jsachs@dl-c.com), April 05, 2000.

Steve, Smile's price may not be that far off from other New York dealers. Adorama's web site has the lens listed at $2,199.95. I've been checking the B&H site regularly but nothing yet. However that doesn't mean they don't have it. They aren't the fastest in web page updates. Maybe I'll call them.

-- Garrett Adams (gadams@jps.net), April 07, 2000.