Macro Extension tube for Pentax K2000 K-7 K-m K20D K10D

This compact and lightweight extension ring set slides on or off your camera in seconds to achieve a wide range of magnification ratios. Each of the extension rings included can be used alone or in combination to vary the magnification ratio. The shorter the distance between the object and the lens, the longer the magnification ratio is. They provide an easy way to compose, focus and meter at the brightest, fullest aperture without stopping down the lens manually before shooting. Through-the-lens (TTL) exposure control will automatically compensate for the lens extension.

The magnification ratio is calculated as follows:

(Assuming that the lens is set to infinity)

                                     Length of added extension
Magnification ratio = ----------------------------------------   
                                       Focal length of the lens

Effective aperture = (Set Aperture) x (1 + Magnification ratio) 

This ring set consists of 5 rings. It perfectly couples with spot metering and AE mechanisms. The ring that attaches to the camera has male thread while that attaches to the lens has female bayonet mount type. For the other 3 rings, the male thread matches with the female one so there are altogether 7 combinations to obtain various magnifications. The lengths of the three rings are 9mm, 16mm and 30mm respectively. All measurements are from the image plane marked on the camera body to the object. 

** Please note that you can only use manual focusing when the rings are in use. Moreover, lenses without aperture control ring do not work with the tube. Please check your lenses carefully before purchasing the extension tube.