TeleVue T-Ring Adapter for 1.25" Powermates

After unscrewing the black 1.25" eyepiece holder from the chrome barrel containing the optics of the Powermate, the adapter threads directly onto the chrome barrel in place of the eyepiece holder. The adapter has T-threads that allow a T-ring to be attached to the adapter so you can connect your DSLR camera body directly to the Powermate optics for photography. 

This adapter is particularly well suited for photography with short focal length refractors capable of using 1.25" visual accessories, such as most of those from TeleVue. It provides intermediate magnifications for terrestrial and lunar photography, etc. - bright subjects that need more magnification than prime focus can provide, but not as much as that normally provided by eyepiece projection photography. 

A CCD imager can be attached directly to the adapter after removing the imager's 1.25" nosepiece to expose the imager's female T-threads. The magnification varies (compared with prime focus photography) depending on which Powermate is used and the spacing between the top surface of the Powermate optics and the imaging surface (the DSLR or CCD's chip). 

With the 2.5x Powermate, the magnification will decrease linearly from 2.5x at a 1mm spacing to 2.2x at a 100mm spacing. With the 5x Powermate, the magnification will increase linearly from 5x at 1mm to 7.75x at 100mm. Exposure times will likewise increase considerably. The exact amount will depend on the magnification gain. With the bright subjects this type of photography is suited for, such an increase in exposure time is normally of little concern.