Fr-237 Focal reducer lens threads directly into the 1.25" nosepiece of an ST-5C, ST-237, STV, PixCel 255 or PixCel 237. When the focal reducer lens is used on an f/10 SCT it will increase the field of view and reduce exposures by several times. It can provide unvignetted operation at f/5.95 or f/3.75 by selecting a fixed mechanical extension tube. The same lens when used the eFinder assembly extension tube turns the FR-237 lrnd into an ultra compact f/4 telescope of 100mm focal length for wide field views or autoguiding without and additional optical tube.
245.00 new. My price in like new condition 110. plus shipping.