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(meteorobs) [IMO-News] The best focal length for meteors




A very interesting query from Daniel Fischer. Forwarded without permission.

Lew Gramer


------- Forwarded Message

Date: Thu, 2 Dec 1999 17:26:28 +0100 (MET)
To: imo-news@egroups.com
Subject: [IMO-News] The best focal length for meteors
From: Daniel Fischer <dfischer@astro.uni-bonndot de>

In http://www.imodot net/photo/index.html it is said that "very good results
can be obtained with the f/1.8, f=50 mm standard lens" and that "shorter
focal lenghts often result in disappointing photographs, not in more
meteors" - but I think that statement (that held true for me during the
1993 Perseids, BTW) might face revision after the 1999 Leonids.

I've now seen or learnt of several pictures taken with 24 mm f/2.8 lenses
during the peak of the storm from a perfect site (Jordanian desert) that
show between 40 and 70 clearly visible meteor trails - see e.g. 
http://www.astro.uni-bonndot de/~dfischer/leo99/iyan.html - while those
using "traditional" 50 mm lenses rarely got more than a dozen meteors
(see http://www.astro.uni-bonndot de/~dfischer/leo99/meteore.html for my
own results from exactly the same site) per 10 minutes exposure.

Why is that? Did the meteors have a peculiar brightness distribution
during the storm peak? Although visual observers agreed on the general
faintness of the meteors, apparently there were not enough specimens of
the 'right' magnitude to offset the 4 times smaller FOV of a 50 mm lens
compared to a 24 mm lens, despite the much higher sensitivity. I wonder
what the lessons are we can learn from that, w.r.t. future Leonid
adventures and meteor photography in general...

Daniel Fischer

------- End of Forwarded Message

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