The Hotech SCA system ensures this premium quality 2-element multicoated optical flattener is positioned precisely on the optical axis for optimum results.
Suitable for f5-f8 refractor telescopes.
The spacing (from the attachment point to the camera sensor) is 55mm so, if using a DSLR camera, you need only a T-Ring.
"The flattener lived up to the claims and now I have the ability to image at the na- tive focal length of my Borg 125SD! Overall, I found the Hotech SCA Field Flattener to be a well-made, well-designed unit and I would recommend it. The coatings on the optics do not add any aberrations, and the flattener provides a very crisp and clear image all the way across the frame of the image." Alan Smallbone writing for 'Astronomy Technology Today'
Review of Hotech SCA Field Flattener