Re: [APML] Leonid Film Queston

["Ulrich Beinert" <analemma@gmx.de>]

Hey Dave,

I've got a program on my site that calculates the relative efficiency of a
given lens/camera combination when they are used for meteor photography.
This can be found here: http://www.analemma.de/english/download.html

I'm rather active in meteor photography myself and have managed to get a few
brighter meteors in my rather short lifetime, and just recently, I built an
allsky camera which uses a medium format fisheye lens (30mm f/3.5), that
projects the entire sky onto 9x12 sheet film - really cool! During the last
Perseids (last quarter moon, haze), I caught a total of 4 brighter meteors
in 6 hours on T-Max 400 film. The camera doesn't capture faint meteors, but
because it covers the entire sky, its rating with my calculator is
relatively high. T-Max 400 seems to have perfect reciprocity characteristics
for meteor photography. In very short exposures (1/10,000 sec.) it needs
*no* reciprocity failure correction, which is very good, as this is about
the exposure time for the meteor image on one film grain. Going the other
way, the film just about fails when doing 100 second exposures, so you'll be
gathering almost no sky fog! It may not be *that* extreme, but those are the
values from the box, and the film works for me.

When I'm using my 35mm camera cluster though, I use T-Max 3200, which has
acceptable grain, and is nice and sensitive to those faint meteors. The only
problem with this is that you need a dark (>6.0m) and moonless sky. The moon
isn't a problem with this year's Leonids, so drive to the darkest place you
know, set up a tent there, and have fun! And don't forget to post your
results...

Ulrich

-----Original Message-----
From: Aplanatic@aol.com <Aplanatic@aol.com>
To: astro-photo@seds.org <astro-photo@seds.org>
Date: Sunday, October 07, 2001 05:30
Subject: Re: [APML] Leonid Film Queston


>Hey, you folks are great.  It's really a treat to ask a question on this
>list.  I always get intelligent answers.
>
>OK, the 100 mm zoom will go down to f/4 and it works pretty well there.
The
>idea is this:  Take a long exposure image of Barnard's Loop and if I win
the
>lottery <g> a fireball will go right thru the center.  Even though chances
>are small, if you don't try....
>
>Yes, the 50 mm will go down to f/1.8 but the aberrations in the corner are
>pretty ratty.  At f/2.8 not too bad, so maybe I'll try it there.
>
>Sounds like I need to buy or borrow a 28 mm f/2.
>
>Thanks again for the advice.
>
>Bert:  The observatory is started.  We will pour some concrete for the
>footings and pier next week.
>
>Tony:  The weather is usually decent this time of year at my place in the
>Mojave, but if it looks bad I'm driving all the way to NM if needs be.  I'm
>not missing this one.
>
>Jerry:  Great stuff, thanks.  I'm not much of a 35 mm buff and have never
>tried my hand at meteor photography.  Maybe I can invoke beginner's luck??
>
>Thanks so much.
>
>Dave Rowe
>
>
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