Astro-Physics S155EDFFF 4" Prime Focus Field Flattener for 155 f/7 and 140 f/7.5 StarFire EDF
The S155EDFFF 4" Prime Focus Field Flattener was originally produced for the 155 f/7 StarFire EDF with its 4" focuser and was included with those instruments. It is now available as an accessory for owners of the 155 f/7 StarFire EDFS version who have upgraded their 2.7" focusers to the 4" model. It is also the perfect Field Flattener for the 140 f7.5 StarFire EDF when purchased with the optional 4" focuser (140EDF4) . These 4" Prime Focus Field Flatteners come with two beautifully machined, felt-lined aluminum covers to protect the valuable optics inside.
This optical marvel was originally designed to take full advantage of the medium format Pentax 6x7 camera, and will provide pinpoint stars all the way to the edge of its field with no vignetting! It is perfect for today's larger CCD cameras as well. We also offer an adapter that allows this Field Flattener to be used with the more conventional SLR's - either 35mm or digital (including a larger clear aperture version for the full format Canon EOS cameras) . The S155EDFFF flattens the field across a full 4" circle without significantly changing the native focal ratio of the telescope - The 155 f/7 operates at about f/7.3 while the 140 f/7.5 will operate at f/7.8.
In the past, most CCD cameras had to be attached using a 2" adapter and nosepiece - see image below left - but we now have two direct adapters for the larger format STL series of cameras (ADA671 & ADA672) that are similar to the ones available for the 155TCC Telecompressor Corrector, the other outstanding 4" imaging accessory for both the 155 f/7 and 140 f/7.5 StarFire EDF instruments.
Diagrams and Instruction Sheets:
Astro-Physics Prime Focus Field Flatteners- Exploded diagram showing the field flatteners with a variety of accessories. Note that this is a PDF file. Read hint for viewing this two-page diagram. Installing the CCD Adapter to Use the 2.7" or 4" Field Flatteners with a CCD Camera - Instruction sheet in PDF format.