I just installed a 6.3 focal reducer on my RCX 10 inch F8 scope and am now unable to plate solve for the initialization. I changed the unbinned image scale to 1.16 arcsec/pixel (from 0.75 arcsec/pixel) and the focal length to 131.7 cm (from 203.2 cm). I am not sure what value to give for the pixel size. This is 7.4 in the original configuration. In any case the initialization fails with the error message that the plate solving failed.

Larry

Larry,

Your pixel size is the physical size of the pixels in your camera and therefore are not affected by the focal reducer.

Since you successfully plate solved before installing the reducer, it is probable your reduced focal length is not correct. You don't say what you are using for plate solving but if you have TheSky, use the image link function to determine your actual plate scale with the reducer. Once you determine that, you can calculate your effective FL by this formula:

FL = 206 * pixel size / unbinned image scale.