Filters for 16200

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akulapanam avatar
I currently have Optolong LRGB filters that I'm using with my 16200 based camera.  I'm finding that my blue frames need 2 minutes of extra exposure to get close to the same ADU of my R and G frames (if R&G are 1200 then blue might only be 200-300 for the same exposure time).  Thinking about buying Chroma, Astronomik, or Astrodon type E filters as replacements.  Was curious if some individuals could post what they get for background values for their RGB frames with Chroma and Astronomik Deep Sky in particular.
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Ruediger avatar
Hi, I also owned a KAF16200 based CCD and had observed the same behaviour, but this was not related to the filters. If you check the tec specs for the sensor you will see, the quantum efficiency is at lowest for blue frequencies. That is the main reason. This is based on the effect that photons can not penetrated deep enough into the CCD semiconductor.
This effect is valid for almost all CCD.
Reference: https://www.onsemi.com/pub/Collateral/KAF-16200-D.PDF
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akulapanam avatar
Yeah I get that but the difference is too large to be explained by the sensor alone.  I have had a couple people provide Astrodon examples now and they are within 10% of each other.
Morian avatar
But also keep in mind that transparency is not necessarily the same from one day to the next, if you do not take them the same evening
I also checked my RGB in SGP around a project I also have Optolong filters.