**Negative
Projection**

This screen allows the computation Negative image projection from a telescope thru a secondary eyepiece lens to the camera or CCD. Enter any four of the five inputs Focal Length-F length, Aperture - Dia both in mm, Effective Focal Ratio EFR, Focal Length of Camera – Fc and or Eyepiece Focal length Fe. Press “Calculate” to figure the missing parameters. Press “Clear” to clear the variables to try new ones.

The next section is the Effective Focal Length for Negative Projection. In this case I have entered the Primary Focal length - Flen, Primary Aperture – Dia, Camera Focal Length – Lc and finally the Barlow Lens Distance to the Image Plane (B or S2 from image). Press the “Calculate” to compute the EFR Effective Focal Length and the Magnification in diopters. Press “Clear” to clear all variables and refigure the calculation.