Prime Focus

DSLR with ACM-2000 Adapter

In general, for the widest image field using a telescope, use Prime Focus photography. This technique uses the telescope in place of the camera lens. It requires a cameras with a removable lenses and available T-Ring accessory (check with any photo store).

To maximum contrast in your prime focus photography, use the Tele Vue Camera adapters. Blackened anti-reflection threads minimize stray light reflections. To enhance your creative palette, we machined 48mm filter threads into the end of the adapter. Fits standard DSLR camera T-rings.  Available for 2" and 1¼" focusers.

Field of View
You can calculate the field size of the resulting Prime-Focus images as follows:

Field Angle° = (Imaging Chip Dimension ÷ Telescope Focal Length)  x 57.3°

The most popular cameras used for Prime Focus are Full-Size and APS-C sized Digital SLRs. Employing the above equation, the following example fields of view are for a TV-85 (600mm focal length):

DSLR with Full-Size chip (36mm x 24mm) on the TV-85 will yield:

Field Angle (long dimension) = 36 ÷ 600 x 57.3° = 3.44°
Field Angle (short dimension) = 24 ÷ 600 x 57.3° = 2.29°

Field Angle (long dimension) = 22 ÷ 600 x 57.3° = 2.10°
Field Angle (short dimension) = 15 ÷ 600 x 57.3° = 1.43°

DSLR with ACM-2000 attached to TV-76