Re: [APML] Exposure time with filter

[Robert Reeves <reeves10@swbell.net>]

> It does make sense Robert thanks. Sounds like a low transmission % though!
> Maybe better suited for Schmidt cameras than my f/3.3 Takahashi.
> Jim

Well... yes, the #92 may pass only 3/4 of the H-Alpha, but realistically how
much is that?  That's only 1/2 f/stop less.  Small potatoes really.
Remember that the filter is also reducing light pollution by 90% or more, so
the exposure can be MUCH longer, way, WAY more than making up for the 25%
loss of the H-Alpha wavelength.  It really does alow shots that would be
impossible on film without the filter.

Robert Reeves                      reeves10@swbell.net
520 Rittiman Rd.                   www.robertreeves.com
San Antonio, Texas 78209    210-828-9036
USA                                     29.484  98.440  200 meters


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