Long Perng 2” 0.8x Field Flattener / Reducer for f/5 - f/7 Refractor Telescopes (with M42 T/T2 Thread)

The Long-Perng 0.8x focal reducer/field flattener # K0.8X-AU minimizes field curvature caused by the objective lenses of fast refractors and provides a sharper image across the camera sensor. It also reduces the effective focal length of a telescope by 0.8x to allow wider-field imaging and faster exposure times.

The optical design of this reducer/flattener makes it optimal for use with refractors with a focal ratio of approximately f/5 to f/7 when used with an APS-C sensor. With smaller sensor 1” and 4/3” cameras, it can work well with refractors slightly outside this range of focal ratio.

With standard male M42x0.75 T/T2 threads to interface with the camera, this 2” reducer/flattener provides a clear aperture of 38mm which is suitable for use with cameras with APS-C sensors and smaller.

An M48-threaded version of this item is also sold separately. Or you can buy an optional Long Perng M48x0.75 adapter to convert this M42 version to the M48 version later should you want to have both options. When used in the M48 configuration, this item delivers an image circle of 42mm, almost large enough for use with full-frame cameras.

The flattener’s nosepiece slides into any standard 2” telescope focuser. Note: The nosepiece has a female M48x0.6 thread on the telescope side and will only accept Orion 2” filters - it will NOT accept most other 2” filters on the market which use the more common M48x0.75 threads.

The Long Perng 2” 0.8x reducer/flattener requires a standard back focus of 55mm. This makes it ideal for DSLR cameras with a standard T-ring (sold separately). It also works with most other astronomy cameras when matched with suitable extension rings (sold separately).

This reducer/flattener features fully multi-coated optics in an anodized CNC-machined aluminum body with a polished gloss black finish.