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Old 08-19-2008, 03:59 AM
SteveL SteveL is offline
Join Date: Nov 2007
Location: Cambridge, UK
Posts: 38
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Default f/2 and Light Pollution Filters

Hi all

I own an IDAS LP filter as well as an Astronomik CLS filter, and although the IDAS is the weapon of choice on my normal kit (f/10 to f/5.7), I believe the IDAS's blocking of specific and narrow light pollution wavelengths is being hampered by the ~6nm shift due to imaging at f/2. I definitely see some light pollution bleed in my Hyperstar images... not as bad as it could be, but certainly not as good as when it is used on slower focal ratio kit.

The CLS filter doesnt "bleed" light pollution in, but then it blocks the light pollution in one large block, rather than specific notches for specific wavelengths. So, it does the job even at f/2, but the effect it has on the image is quite drastic, with large sections of color going missing compared to images without using a filter, or using the IDAS filter.

I was wondering what other light pollution filters people here have used, and what they recommend.

Yes, I want the best of both worlds And I want it today!
NS8GPS/WOZS66/Hyperstar v3, EQ6ProSynScan/ED80Pro/C11, QHY8, PST, DSI, NexImage, Canon 350D, and 100% cloud cover
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