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Old 13-03-2015, 11:48 AM
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traveller (Bo)
Not enough time and money

traveller is offline
Join Date: Aug 2011
Location: Melbourne
Posts: 2,120
Originally Posted by pmrid View Post
That's interesting.

I had assumed (wongly it would seem) that without a filter, your sensor would be open to the entire spectrum and therefore be prone to excessive sky-glow effects - the Baader UV/IR cut filters (the ACF varieties) have a very sharp gradient at both ends and extend the red end only enough to capture the bulk of Ha. If anyone has any more info on this, please post. I'm heading to Google now to see what I can find there.
You are partially correct Peter. Canon DLSRs have two filters in front of the sensor (with the glass stuck on). The first is a "pink" filter which has uv/IR cut function. The second is a "blue" filter used to filter the light spectrum to mimic the human eye response. If you remove the pink and blue filter, you will lose autofocus and the camera is a full spectrum mod. If you just remove the blue filter and keep the pink filter in, the Ha response is increased in the same manner as a full spectrum mod, the uv and IR end are filtered out and the autofocus loss is negligible.
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