Re: [APML]Emission Lines Question and missing Veil

[Gene Horr <genehorr@texas.net>]

"William R. Mattil" wrote:

> 8" Schmidt Camera (f/1.5) - ST-4 guiding a GM-100 mount. 90mm f/11
> guidescope. Side x Side
> 
> Film used was unhypered Kodak Royal Gold 100. Exposure times were 30
> minutes.

Even at f/1.5 IMO the film is just not "fast" enough.  Most of the
object is very faint.  I was shooting it with CCD this weekend 
with an 8" f/3 & a ST-8 NABG.  Rough rule of thumb for this chip
is that exposure times are equal to ASA 800.  A 5 minute exposure
barely shows detail and it takes 20 minutes to even begin to get
decent data.

This film probably has a very high "toe" (minimal photon flux 
required to register).  Even at f/1.5 you aren't getting enough 
photons on each grain to register.  Try E-200 or a 400 speed 
print film.  Either should work quite a bit better.

I ran into similar problems with my f/3 instrument.  I thought 
that with such speed film response wouldn't be as much an issue
than what I experienced at f/6.  Bzzzt.  Wrong.  It is still 
just as important.

Gene Horr
genehorr@texas.net

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