(meteorobs) Improving the contrast of all-sky camera & mirror systems. Chris?

[Larry]

Picked up a commercial builders transit today with a broken tripod leg which 
I intend to use to determine (true) horizon. This has started my thinking on 
the faults of both all-sky camera lenses and mirror systems.

Your thoughts on the following comments Chris would be appreciated.

1) Both all-sky fisheye lenses and mirror systems capture the light from 
distant terrestrial objects on an "apparent" horizon which is FAR BELOW the 
actual true horizion. This includes rising and setting Sunlight saturation 
at important fireball recording hours.

2) It appears that our systems see & photograph somewhere around 20 degrees 
or more below the true horizon. (I have not measured that yet).

3) Our practice has been to "Mask" all of this unwanted light from 
triggering our systems. But I do not believe this is the best approach 
because it does nothing to help the camera sensitivity which is based on 
contrast. Street lights that are close are a separate issue if they are 
above the true horizon or even close to the true horizon.

4) My thoughts are that we should be BLOCKING the light below the true 
horizon or maybe blocking all light more than 5 degrees or so below that 
true horizon to improve the operating contrast of our cameras by reducing 
the stray light, artifacts, and saturation that inhibits contrast.

5) A circular black ring, paint stripe, or similar application should be 
placed around the dome or mirror with a height just below or at true 
horizon. Masking should be only employed for lighted objects above the 
elevation selected for blocking if no steps are taken to specifically block 
those too.

This approach may significantly improve our camera sensitivities and/or the 
early evening, early morning, working hours.......

YCSentinel
(P.S. thanks for your classified thoughts earlier.)