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Pentax 200mm SMC Takumar M42 with Step Down Rings, Geoff Scott

Pentax 200mm SMC Takumar M42 with Step Down Rings

Pentax 200mm SMC Takumar M42 with Step Down Rings, Geoff Scott

Pentax 200mm SMC Takumar M42 with Step Down Rings

Description

Having recently acquired an early 1970's Pentax SMC Takumar 200mm f/4 lens with M42 mount and done some initial testing, I acquired a collection of step down rings to give specific f/ratios that avoid diffraction spikes (leave lens at f/4).

The effective aperture of this lens is at f/4 FL=200mm is 50mm, so step down rings are 42mm (f/4.8), 37mm (f/5.4), 30mm (f/6.7) and 25mm (f/8) to avoid internal diaphragm/iris diffraction spikes. Lens shown with 58-37mm fitted.

Comments

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Pentax 200mm SMC Takumar M42 with Step Down Rings, Geoff Scott