Nikon Coolpix 990 Afocal Coupling Vignetting

Afocal Coupling Nikon Coolpix 990 Digital Camera to a telescope

To reduce vignetting it is important to keep the eyepice as close as possible to the Nikon Coolpix 990 camera lens. The 20mm Sirius Plossel eyepiece is a perfect fit in the Universal Camera adapter in that it can be slid back against the 28mm to T-mount Adapter and the securing thumbscrew on the Universal Camera adapter still holds the eyepiece.

The longer 26mm Sirius Plossel requires a Edmund Industrial Optics short T-mount extension tube between the 28mm to T-mount Adapter and the Universal Camera adapter.

The shorter 10mm Sirius Plossel requires an Lumicon 1" thread-in extension tube (LAD110) mounted on the eyepice so that the securing thumbscrew on the Universal Camera adapter can hold the eyepiece.

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