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Old 31-03-2008, 01:38 AM
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EzyStyles (Eric)
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EzyStyles is offline
 
Join Date: Jan 2006
Location: Melbourne, Victoria
Posts: 3,208
ok i think i get it now.

Looking at the Baader BCF filter in my 40d, at 1100nm (where IR range starts at around 715nm - 1100+), it increases all the way to around 1140nm at 80% then drops the IR from 1140nm down to 1160nm at 43% which then shoots back up at 1200nm + at 70% !!! this is where the IR light is coming from.

Adding the LPS2 filter infront of it, at 1050nm it increases the IR to 72% then does a major drop at 1125nm at around 7%. then goes back up at 1125nm. That "bump" in the curve helps to cut down a slight amount of IR light with the LPS2 filter but it doesn't cut the IR light fully hence that is why it slightly works with the LPS2 filter but not 100%.

Overall, between 1100nm and 1200nm is the IR range i need to cut to make my images normal again. The baader UV/IR filter graph as seen here http://www.alpineastro.com/filters/uv_ir_cut_specs.htm cuts the 1100nm/1200nm range.

arhhhhh im beginning to get it after looking at it a few more times and a bit of research.
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