A high quality dual element 0.8x Field Flattener / Reducer for use with Starwave 70ED Refractor and Nikon DSLR.
The field flattener improves the quality of star images toward the field edges and decreases the focal ratio from F6 to F4.8.
The focal length of the telescope decreases from 420mm to 336mm.
Everything you need to connect your Nikon DSLR to your Starwave refractor is included in the kit.
- Field flattener body with standard 2" push-fit barrel on the front, and M48x0.75 male rear thread.
- M48x0.75 spacer to create the optimum spacing for Nikon cameras.
- Nikon M48 adapter which screws into the M48 spacer, and fits to the camera body, just like any Nikon camera lens.
All lenses are fully multicoated and are made from the finest optical glass, housed in a CNC machined, black anodised aluminium body.
A rubber cap is included to cover the 2" push-fit barrel, and a metal threaded M48 cap is included to cover the rear optical element.
The Nikon adapter has an inner ring with M48 thread. 3x small grub screws spaced 120 degrees apart are located around the edges, allowing the M48 thread to be removed from the Nikon adapter. These grub screws may need to be tightened up on first use. You can check this by rotating the Nikon bayonet adapter against the . Simply screw the Nikon bayonet adapter onto the M48 spacer, which is already attached to the rear of the flattener. Note: A small silver indexing cross-head screw is located in the Nikon bayonet adapter for use with older Nikon F-mount lenses. If the Nikon lens does not click into place first time, this screw can be removed and discarded for use with more modern lenses.
How does it work and why do I need it? All refractor lens systems exhibit some natural field curvature, which, while not relevant for visual observation, can be visible in photographic images. This field flattener/reducer has a 2" push fit barrel which can be inserted directly into the rear focuser of your Starwave 70ED or refractor, converting it into a fast astrograph with a faster focal length and a flatter photographic field than the existing lens system alone. By reducing the focal length by a factor of 0.8x, you get a faster focal ratio, therefore exposure times are reduced by a ratio of 1:1.56 compared to the normal exposure time. In photographic terms this is expressed as a gain of +0.64EV.