Description
Needed to achieve the 55mm back focus distance with cameras that have a shorter native back focus than a DSLR. Available in various thicknesses (e.g., 11mm, 16.5mm, 21mm). Check your camera’s specs and add spacers to make up the difference.
Final Thoughts
If you own an AT90CFT or AT90EDX and you’re imaging with it, this is not an optional accessory it’s the other half of the imaging system. The scope gives you the light and the color correction. The reducer gives you the speed and the flat field. Stars round to the corners, exposures cut by more than a third, and the whole thing threads together without adapters or guesswork. Dedicated, matched, done.
Tech Details:
| Product Type | Focal reducer and field flattener |
| Reduction Factor | 0.8x |
| Compatible Telescopes | Astro-Tech AT90CFT and AT90EDX 90mm f/6 triplet APO refractors |
| Resulting Focal Length | 432mm (from 540mm native) |
| Resulting Focal Ratio | f/4.8 (from f/6 native) |
| Coatings | Fully multi-coated |
| Scope-Side Connection | M631 metric thread (threads into focuser or camera angle adjuster) |
| Camera-Side Connection | 48mm T-thread |
| Back Focus | 55mm (shoulder of reducer to image plane) |
| Filter Holder | Built-in 48mm (2″) threaded filter holder (accessible by unthreading top cap) |
| Weight | 9 oz |
| Included | Reducer/flattener, slip-on rubber cover for T-threads, slip-on cover for scope-side barrel |
| Product Manual | Included (PDF download on product page) |
| Warranty | 1 year manufacturer warranty |
Reviews
There are no reviews yet.