I have the 165mm f/2.8 which is fine except.... Sometimes I need a longer focal length, and at a fast aperture. I suppose the new 300/4 will be a great lens, but I really need a faster aperture. Is there any hope that Pentax will make something like an 250mm f/2.8, someday?

-dan strawberry9@worldnet.att.net

-- dan (strawberry9@worldnet.att.net), January 23, 2000

Answers

Once you get into the 150mm+ focal lengths, there is always a problem with color correction. A fast 250mm would need expensive(ED) glass if it were to be sharp wide open. A symmetrical design would be better than the traditional telephoto types because of cost reasons. An ED Double Gauss or Plasmat might be the solution. Pentax does not use experimental designs like I'm suggesting above in the focal lengths over 200mm. Mamiya used a Plasmat design in their 80mm for the Mamiya 7. Plasmats have been used in view cameras for years so it goes to show that some optical companies are experimental. Only Pentax's newer 55mm is a unique design of their lineup. The chances of Pentax making a 250 f/2.8 are very remote. SR

-- Steve Rasmussen (srasmuss@flash.net), January 23, 2000.