[Boggy (Barry)]

Could anyone recommend a field flattener that might work with a William Optics Zenithstar 110mm F7.0 refractor (the old black and gold model). I've just started trying to do some astrophotography and am getting some curvature, otherwise the results are very good!
The telescope is about 14 years old and uses a standard 2 in focuser.
Thanks for your advice.