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The instruction manual for the Celestron #94240 0.7x Reducer Lens for the EdgeHD 14” indicates that the focal length with this lens in place is 2,488 mm (98”). This appears to be a typographical error as that would be F/6.3. Note that F/11 * 0.7 is F/7.7.
Alas, in the real world I'm measuring (via plate solve) closer to F/7.8.
I have the reducer attached to the back of my EdgeHD 14 with my CCD camera set so that the chip is 146mm behind the reducer exactly as the measurement is shown in the manual. The star images are nice and round.
If I move the camera farther back I can get to F/7.7, but then the stars become egg shaped just as the manual warns ("elongated star images toward the edge").
Overall I'm very happy with this reducer.
For me the benefits are:
1. Larger field of view at F/7.8.
2. Preserves the 146mm original backfocus.
3. Makes the device attached immediately after it in the image train clear the mirror lock knobs and the focus knob. Atlas focuser, here I come! Pyxis 2" rotator, here I come!
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