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There was a lot of internet posting about reflections and halos about 2 -3 years ago when the first Apogee and FLI 16803 chipped cameras were released.
The STL11 chip is half the size of the 16803 so you are not comparing apples with apples there and the reflection debate started with the 16803.
It seemed to mainly be prevalent with scopes that use correctors.
To be clear that is all scopes with a 16803 chip. Even an RCOS. An RCOS probably could get away without using one but it would lose its tight stars further offaxis which the correctors/flatteners fix.
The usual fixes were:
1. A new range of antireflection coatings on filters (Astrodons were some of the worst offenders as they are mirrored type filters) So you now have several offering Generation 11 filters. I use Astrdon Gen 11 filters and those coatings work well.
2. Cameras had aperture masks installed.
3. Apogee and FLI offer no cover slip versions of their cameras as these can cause small halos around stars.
4. CCD Window needs to have antireflection coatings and be of good quality material. FLI addressed this very well.
5. Edges of filters need to be blackened. Baaders need to have the blackening extend onto the face of the filter 1mm as the coating ends just before the edge (a different manufacturing approach).
6. Most reflections seem to bounce off the correctors/flatteners and the filters and then bounce around anything not nailed down reflection wise. As Mike says any bright parts, anything anodised (highly reflective in IR).
But the biggest fix seems to be the choice of filters.
So if you are thinking of getting one of these cameras chose the filters carefully. They don't all perform the same.
Greg.
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