Re: [APML] Films responding to Ha, Hb, OIII

[Ray Butler <ray.butler@nuigalway.ie>]

And welcome from me too, Michael.

You might also consider that since most colour print films are pretty
dead to H-alpha, and poor enough in the blue-green region of H-beta and
OIII, another alternative with a nebula filter is to use black and white
film. This will perform really well on H-beta and OIII because it
doesn't have the "falling between two stools" sensitivity problem that
colour films (both prints + slides) have in this part of the spectrum,
where their blue and green curves dip and cross over each other.

There is a tradeoff, which is that you can't expect to pick up much or
any H-alpha (unless you use some hypered Tech Pan, while it's still
available). But for the filtered H-beta->OIII region (which is so narrow 
that a monochrome film is most appropriate anyway), B&W is ideal.

And if you use a C41-process "chromogenic" B&W film, you can have your
film processed anywhere that develops colour print film. Kodak TC400N is
probably the best choice since it has extremely good reciprocity
characteristics, according to Michael Covington's tests. Apparently it
is now renamed Portra B&W or Kodak B&W. As always, check the film's 
spectral sensitivity curves on the spec sheets first. Here are the Kodak 
B&W specs (which look fine for H-beta->OIII):
http://www.kodak.com/global/en/consumer/products/techInfo/f15/f15.shtml

Ray "testing this film soon" Butler


Michael Barlow wrote:

> Hey gang, I'm new to the list,
> 
>     I've been photographing nearly two years but have never got in to the
> technical side of it.  All I've been doing is grabbing film off the shelf
> (color print film) at the local grocery store and department stores for
> Lunar, Planetary, and white light Solar through my 8" SCT.  Just the last
> couple weeks I've been grabbing shots of M31, M45, and snapping away at what
> ever else I happen to see and wanted to step in to filtered photo's such as
> Ha, Hb, OIII, and ect...  I just bought a Meade #911 Nebular filter for the
> SCT and just learned that most films have been reformatted to virtually
> eliminate responses from Ha but haven't heard anything about the other two,
> Hb, OIII.  For the beginner in the filtered end of photographing in one or
> all the above frequencies, Is there a cheap 35mm film that responds well
> enough to learn from, color or B/W?  I.E. Until I get my feet wet I'd rather
> not buy expensive Hypered film or anything that costs over $5 US per roll.
> 
> Michael A. Barlow
> 
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-- 
Dr. Ray Butler (ray.butler@nuigalway.ie || ray@physics.nuigalway.ie)
Lecturer, Dept. of Physics || Computational Astrophysics Laboratory
National University of Ireland, Galway, University Road, Galway, Ireland.
Tel: +353-91-524411 ext. 3788   FAX: +353-91-525700


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