ProOptic 8mm f/3.5 Manual Focus, Fish Eye Lens with Pentax Mount.

The 8mm f/3.5 Pro Optic Fish-Eye CS lens is a breakthrough in optical design producing the first affordable fish-eye lens designed for digital SLRs that have APS-sized sensors. APS-C sensors have a multiplication factor of 1.5 or 1.6x so the effect the lens produces will vary slightly between cameras. The well-constructed and precision designed lens features a built in lens hood and a sturdy locking lens cap to protect the large front element from damage when it's stored or not being used to make photographs. The optical construction consists of ten elements in seven groups and is computer optimized to produce clear, crisp photographs, which is critical with a lens like this that is capable of extreme depth-of-field. When set at f/22 the result is a great range in depth-of-field that makes focusing less critical.The field of view with the APS-sized sensor is a full 180° producing the kind of super wide-angle view found only in much more expensive lenses. With a close focusing distance of just 12 inches and its outstanding angle-of-view and deep depth-of-field, users will be able to produce truly unusual and dramatic close-up photographs. The compact size makes it ideal for travel photographers who want to add new perspectives to their work. The lens is also perfect for architectural interiors, landscapes, and special effects photography. And for infra-red eXPLORers this lens will open up a new world.