Quote:
Originally Posted by Tandum
Where do you see them at that price Merlin?
Have you tried this Ian? Looking at response curves for the default canon IR Filter, it blocks 70% of Ha at 656 and 80% of SII at 673, so your exposure time would need to be two to three times longer than with a Baader IR Filter installed plus only the red pixels will be detecting anything. I'd never get decent images if I had to do 30minute exposures.
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Yes - I've seen the sensitivity curve for the 40D modded and standard chip. I've also seen how modded 400D and 40D DSLRs perform for normal photography even after images have been post processed to compensate for the horrible white balance - way not impressed !! Thoroughly investigated this back in June before I bit the bullet and bought the 40D and made my decision that modding was not necessary and has more cons than advantages (for me).
Not a big deal that the sensitivity is less than 10% at the IR end, it is still capable of recording photons , all you need to do is compensate for the lower relative sensitivity by using longer exposures (or more subs) if you need to record that data.
The stock fllter blocks 70% of Ha at 656nm
==> 30% of the Ha still gets through (so use a Ha narrow band filter and 2-3x the exposure)
and 80% of SII at 673nm
==> 20% of SII still gets through (so use a SII narrow band filter and 4x the exposure).