Universal Astro 2" Adjustable Field flattener for f/5 to f/7 refractor telescopes

The Universal Astro photographic field flattener reduces the normal field curvature inherent in all refractors to provide you with images that are sharply focused out to the very corners APS-C imager frame. Stars on your images look sharp and point-like all the way across the field. You don't have to worry about photos that are sharp in the center but out of focus at the edges. The field flattener also works surprisingly well with the 6", 8", and 10" Astro-Tech Ritchey-Chrétien astrographic reflectors.

Designed to work purely as a field flattener for imaging, and not simultaneously as a focal reducer or telecompressor, the 2" Universal Astro Adjustable field flattener does not change the focal length or focal ratio of your telescope. It is not designed for visual use, having 48mm photographic T-threads only and no provision for using a star diagonal or eyepieces.

The 2" barrel of the fully multicoated Universal Astro field flattener inserts directly into your scope's 2" focuser drawtube. A groove machined into the field flattener barrel engages the thumbscrew or compression ring of your focuser to act as a safety stop. This prevents the field flattener and camera from falling to the ground should the thumbscrew or compression ring accidentally loosen during use.

The Universal Astro Adustable field flattener comes with a threaded adapter top for 48mm x 0.75mm pitch T-2 photographic T-threads on the observer/camera side of the black anodized field flattener accept a standard T-ring for connecting a 35mm or DSLR camera to the field flattener. They also allow direct connection to many CCD or CMOS camera/color filter wheel combinations.

Spacing from field flattener to film plane: Optimal spacing from the shoulder of the field flattener (where a T-ring threads on) to a camera's imaging sensor or film plane is 57mm +/- 4mm. The great thing about this adapter is it lets you dial in the perfect backspacing from 55mm to 80mm with just a simple twist of the body.  The locking mechanism will make sure that your spacing doesn't change while you are imaging.