Reducer Field Flattener 0,8x 2"

The flattener is a lens that evens out the field, as this is slightly curved by the primary optics. This curvature causes stars that are imaged at the edge of the field of view to be less sharp. The flattener, also called a field flattener, corrects this effect. Astrophotographers can then enjoy images where the stars remain sharp right out to the edge of the exposure. The flattener is installed between the telescope and the camera.

The Reducer (for focal length reduction) is an optical accessory that allows a more favourable aperture ratio. Required exposure times are hence shorter and the optics 'faster'. Also, the field of view increases, so that even larger astronomical objects can be observed or photographed.

Back focus: The reducer/flattener has a spacer ring. When this is unscrewed, the back focus is 55 millimetres. This is ideal for most DSLR cameras.

Depending on the focal length of your apochromat, the following back focus is required:

• Focal length up to 350 mm: 70 mm
• Focal length up to 420 mm: 65 mm
• Focal length from 450 to 500 mm: 61 mm
• Focal length from 510 to 600 mm: 58 mm
• Focal length from 610 to 700 mm: 57 mm
• Focal length from 710 to 790 mm: 56 mm
• Focal length from 800 mm: 55 mm

Use an extension tube (fine adjustment ring) in addition to the spacer ring supplied to set the required distance. For example, if you have an Apo with a focal length of 600 mm, you need an additional 3 mm distance to the 55 mm back focus of the flattener with the tube supplied.