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Re: (meteorobs) Video meteor advice

Lew,

> They are being offered a fisheye lens along with one setup: this is billed as 
> the "Meteor Catcher Lens". That made me curious, as I'd always understood that 
> a 50mm or other "normal" lens was generally used for videometeors. So I'm 
> wondering: what are the best lens choices, and what are the tradeoffs?

it depends... :-)

If you want to catch numerous bright meteors of a large meteor shower, a
wide angle (or even fisheye) lens is certainly of advantage. You monitor a
larger field of view and the limiting magnitude is lower. Hence, the
average meteor brightness is larger as for standard or tele lenses.

If, however, the accuracy of position measurements shall be optimized, you
better take a lenses with a longer focal length. The field of view is
smaller, hence, the spatial resolution is better.

When taking the plain number of recorded meteors as a measurement of
efficiency, wide angle, standard, and tele lenses show approximately the
same performance, i.e. the larger field of view of wide angle systems
compensates for the lower limiting magnitude.

However, the percentage of shower meteors is decreasing with an incresing 
focal length of your lens, as most meteor showers have a lower population
index than the sporadics. To say it with other words: If you increase the
limiting magnitude by 1 mag, the number of shower meteors is increasing by
a factor of about 1.8 ... 2.5 (depending on the population index of the
shower) , whereas the number of sporadic meteors is increasing by about a
factor of 3.

BTW, I usually use two different setups: When doing single station
observations I choose a wide angle lens, whereas I prefer a standard or
tele lens for multi-station observations.

Cheers, Sirko

--
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*  Dipl.-Inform. Sirko Molau                  *                          *
*  RWTH Aachen, Lehrstuhl fuer Informatik VI  *                          *
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