Large Chip flattener for 2.5” focusers - 48 mm attachment
This flattener is made for our 102 mm to 130 mm f-7 refractors. This includes the doublets and triplets. It threads to the rear of the 2.5" focuser (Stellarvue or Feather Touch). This flattener uses an over-sized 48 mm camera attachment thread. Using one of the over-sized 48 mm T rings, a DSLR camera may be used with this field flattener. This provides a completely threaded mounting solution for larger chip cameras when used a 2.5” focuser. This field flattener requires 55 +/- 0.5mm (standard DSLR) back focus. When using a CCD camera, the remaining back focus required can be made up with 48mm extension tubes.
48mm x .75 pitch threads can be added internally to this field flattener to accommodate most 48mm filters. Check the option box above to add this feature.
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I've tested the large photographic field flattener with a 115mm f7 Stellarvue telescope and a Canon 6D full frame camera. Because of weather I have only been able to test it on a distant tree that filled the frame. With the flattener the leaves and stems were sharp from the center to the edge of the frame, and there was no obvious vignetting. Without the flattener the image of the same tree was very fuzzy in about the outer third of the frame.
I'm using a Stellarvue 90mm APO 'scope and full frame 24M pixel DSLR and the focus is crisp across the whole field including the extreme corners. Vignetting is certainly not obvious although the images I have taken so far would not stress this aspect. The only incident I have had is that the front most ring stayed on the focuser when I took this off.
This flattener along with Stellarvue's 2.5 in focuser has effectively eliminated a serious vignetting and distortion issue I had with my Skywatcher 80's 2 inch hardware. The quality of Stellarvue is 2nd to none. When I move up to a bigger aperture refractor, they are first on my list.