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Re: (meteorobs) Re: photo strategies for Leonids '00?

Hi Micheal:
    It doesn't make sense that you didn't record these bright fireballs.
Peter Millman classified cameras into three categories.

A: Conventional small cameras with f/a between 4.0 and 8.0 and f between 100
and 500 mm. Example: studio and press type cameras.  These should record
meteors down to 0 or -1 magnitude.

B:  Conventional cameras with f/a between 1.0 and 3.5 and f  between 50 and
200 mm.
     Example: miniature (35 mm) cameras and aerial reconnaissance cameras.
These should
     reach 0 or +1.0 magnitude

C:  Schmidt type cameras f/a between 0.5 and 1.0 and f  between 100 and 300
mm.
     These should reach +3 to +4 magnitude.

Today, a class D should be added to include Video Image Intensified LLLTV
systems.  These can reach -6.0 and often fainter.

    This has been my experience doing meteor photography.  I use Tri X most
of the time. I specialize in meteor spectroscopy and the addition of a
dispersive element lowers the faint threshold detectability by 2 to 3
magnitudes.  It all depends on if you use an objective prism or a
transmission blazed grating.  A prism is usually more efficient than a
grating but dispersion is non linear and generally lower, especially at the
red end of the spectrum.  Modern high speed films should extend Millmans
faint magnitude threshold a bit, also.

Ed Majden
http://www.amsmeteors.org/spectro.html



----- Original Message -----
From: Micheal Boschat <mboschat@ns.sympaticodot ca>
To: Meteorobs <meteorobs@jovian.com>
Sent: Friday, November 10, 2000 2:05 PM
Subject: Re: (meteorobs) Re: photo strategies for Leonids '00?


> Hello All;
>
> last year we went 50 miles from the city and I shot using a 50mm f/1.8
lens
> with
> Kodak Gold 400 ASA. I had 3 bright fireballs of at least -6 to -10 mag go
> through the field
> but whne the film was developed I could not find them at all!
>  One I saw go through Orion and had my camera at that area and knew it
went
> through.
> But nothing. Another observer was using a similar lens but 800 ASA film
and
> he only
> got a very faint streak.
>
> Our exposures were always 5 minutes at maximum. I keep my film in the
fridge
> were
> the eggs go and the film does not expire till 2004! I have 100 rolls now
of
> the 24 exposure
> Kodak Gold 400 and wonder if anyone knows why we did not get good images
> like others
> did in the magazines ect?
>
> Thanks
>
> Mike
>
>
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