The ExpoDisc (77mm)  type_Flash Coupling contemporary 4x5 monorail camera with

contemporary 4x5 monorail camera with indexed movements front and rear

clean diaphragm and clean glass

fast standard lens for 4x5 cameras

The SMC Pentax-DA* 50-135mm f2

The ExpoDisc (77mm) &nbsptype_Flash Coupling contemporary 4x5 monorail camera withThe ExpoDisc is a clip on (or hold in front of) diffuser designed to facilitate setting custom white balance. Rather than hauling around a gray card, or trying to find a plain white surface, or hoping that your camera guesses correctly, you can toss this in front of your lens and lock in an accurate custom white balance in seconds. Bonus: if you actually use this on a lens with a 77mm filter thread, it can replace your lenscap. Yeah, its just a fancy