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OIII/HA filters
Might seem like an odd question but does anybody know if it's possible to fit either an OIII or HA filter that suits a 1.25" EP into the photographic line between the OTA and the camera?
I'm using a flattener and an extension tube (10mm) between my 90mm apo and a Canon 550D DSLR.
I'm getting some good results but tried to photograph Sharpless 308 on the weekend and read it's better off with a filter.
Be interested to know.
Cheers.
Steve.
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