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Does a SCT need an IR filter for imaging or video?

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#1 Atl

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Posted 18 April 2013 - 06:05 PM

That is my question. Thanks for a response in advance.

#2 GlennLeDrew

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Posted 18 April 2013 - 10:22 PM

I don't use such a filter with either of my 80mm f/5 achro w/ MFR-5 reducer and 8" SCT w/ 0.33X reducer, with my VSS+ attached. I see no real need. Star images are as crisp as they're going to be, and there are no discernible color oddities...

#3 robininni

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Posted 18 April 2013 - 10:24 PM

It is my understanding that it does not unless you are using lenses (focal reducers, field flatteners, etc.). IR cut filters are for refractors OR other lenses that cause the infrared light to focus differently from the visual light causing muddy images.

Rob

#4 Atl

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Posted 18 April 2013 - 11:36 PM

Thanks for the info. That has been a confusing issue to me. I am not a big fan of filters. My experience with various nebula filters is that they reduce the overall light that reaches the eye.

#5 nytecam

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Posted 19 April 2013 - 03:06 AM

That is my question. Thanks for a response in advance.

I don't use IR-block filter for my SCT imaging even though I use focal reducers [lenses] - under test IR light contributes noticeable to image density - maybe 30%. Blocking IR effectively needs a longer exposure and in brief [video] exposures we need all the light we can get. :grin:

#6 rmollise

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Posted 19 April 2013 - 10:04 AM

It is my understanding that it does not unless you are using lenses (focal reducers, field flatteners, etc.).

Rob


Nope, not even if you are using reducers--as almost all folks doing video do. They are helpful for refractors in keeping star bloat down. ;)






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