Canon 70D Astro converted, Canon 85 mm f/1.8 lens at f/2.8, ISO 1600. Photo courtesy of Ron Brecher.
Filter transmission after the astrophotography modification:
We are happy to now offer astrophotography conversions. We are able to convert cameras to have an expanded spectral response that covers the H-alpha and sulfur II emission lines. After conversion, the camera will have a greater than 4 fold increase in sensitivity in the H-alpha line compared to a stock camera, and a greater than 6 fold increase in sensitivity in the sulfur II line. This conversion will maintain the dust reduction feature in the camera and uses multicoated glass to reduce reflections and artifacts. These cameras can still be used for normal photography when paired with our hotmirror color correcting filter. Above, an actual measured transmission curve of the filter. Internal transmission is close to 100%. Be careful when reading transmission curves, some sources provide the more attractive internal transmission instead. All curves we provide are always measured transmission.
We now support select Canon, Nikon, Sony, and Pentax cameras. Supported models can be found here
We have also had some requests to remove the filters in front of the sensor and put nothing back to maximize possible transmission and even further remove a source of reflections. We are now doing these naked conversions as well. In this conversion, the autofocus will be re calibrated, but as a disclaimer the sensors will be a lot more sensitive to scratches and dust. This conversion can be done to select models with autofocus recalibrated, and to all other models with focus only compatible for telescope use.