K3's AstroPhotography
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

Steven's Mogg webcam adapter and focal reducer 0.6

Steven's Mogg adapter is very popular in QCUIAG. It has reasonable price and good quality. Although I started to do astrophotography with my home-made adapter for webcam, I realised soon, that using webcam in conjuction with long focal lengths (using Barlow) necessary for planetary imaging requires good quality adapter. Finding a planet in webcam field of view (FOV) is very hard (FOV of my Vesta 675 with 2400mm focal length is approximatelly 5' x 4'). So the optical axes of webcam and eyepiece must be the same and even a small innacuracy of home-made adapter can be frustrating. So I decided to order webcam adapter from Steven Mogg. For Philips Vesta and Vesta Pro the proper type is UWAS-F (I ordered an adapter with filter thread).

When I started deep-sky photography, I find out, that focal reducer for my F/6 telescope is necessary. Steve produces very good focal reducer 0.6FR with reducing factor 0.6 (see calculations - Barlow Lens and Focal Reducer). The big advantage of Steve's focal reducer is possibility to still use filters, because 0.6FR has filter thread.
Practical tests with using my webcam and telescope showed real reducing factor 0.613. With such reducing factor it is possible to shorten exposure time by 2.66x. The lower result focal length enables to extend exposure time by 1.63x (with the same star drift). So maximum exposure of the image with the same mount can be extended by 4.33x.

Here are photos of webcam adapter and focal reducer.

Steven's Mogg adapter UWAS-F

Filter thread on UWAS-F

0.6x Focal reduce (0.6FR).

UWAS-F + 0.6FR.

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Last Update: 10.11.2001