They were very cheap many years ago so I bought the 300mm to find out it was giving quite bad images: faded colors (or call it low contrast), distorsion and a very "hot spot" about 24mm in diameter if I remember well. I have some images around.Front of the 300/5.6 - http://www.cetussoft.com/pentax/mirrors/30056.jpgFront of the 500/8 - http://www.cetussoft.com/pentax/mirrors/5008.jpg Back of both lenses - http://www.cetussoft.com/pentax/mirrors/300&500.jpg Fun... Fred
Have you tried them?
Andre
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