|
I have Bintel's Orion focal reducer and also the field flattener. (The reducer is a flattener also I believe). I find they work well to even out the bright center "hotspot" in all my refractors - ED100 F9, 120mm F5, ED80mm F5.5, 100mm F8 etc. The flattener is necessary on the ED80 but the rest are okay without.
I'm not sure about the 102mm F5. Take a pic through it and see if there's any streaking on the corners. If so you need a field flattener.
Of course they do nothing to help the chromatic aberration in the achro refractors. I find a 48mm screw in light yellow photographic filter to be useful for reducing CA in achros. You can find those on ebay cheap, often sold as NOS New Old Stock.
|