For either current owners of the Esprit 120ED or users who are planning on purchasing an Esprit 120ED but want an advantage for imaging, the Esprit 0.77x 120ED Reducer/Flattener is a great add on to have. It serves two important optical purposes that improve the quality of exposures.

On the reducer side of things, it changes the focal ratio from f/7 to an f/5.4, making it more suitable for astrophotography and reducing exposure time by 68%, thus allowing more exposures to be taken in a certain time period.

On the flattener side of things, spherical aberration which can ruin exposures is remedied! What does this mean? Flat images without field curvature is now generated meaning pinpoint stars to the edge of the field of view (when using full frame or Crop sensors). The flattener has a 34mm fully illuminated field of view. For users imaging with a full frame 35mm camera, the field of view is 3.19 x 2.12 degrees and for crop sensors it is a 2.08 x 1.39 degrees.

It also includes a built in 2" filter cell for mounting filters. Ordinarily, there is 95mm backfocus but it can be reduced to 55mm with spacer and M48 ring.

• Sky-Watcher Esprit 120ED 0.77x Reducer/Flattener is a must have for users who want an edge up in their astrophotography.
• Serving dual purposes, the reducer changes the focal ratio from f/7 to f/5.4 while the flattener removes spherical aberration.
• Works for both crop sensors and full frame sensors.
• Includes built in 2" filter cell for mounting different types of filters including but not limited to moon, light pollution nebulae or narrowband.
• 95mm backfocus, but 55mm when used with a spacer and M48 ring.