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Re: [APML] Meteor Photography Questions
Alson,
Stopping down, you would get the bright meteors, but they would not record as well. Particularly with negative film, you can record and want to record a lot of density for good definition of the meteors. The Leonids are fast moving and you need all the speed/aperture you can get.
I would only stop down if the lens had ugly aberration when wide open. Or I would find a better lens.
Lets say you use 11 minutes per exposure and multiple exposures of the same patch of sky, on a tracking mount. Using RegiStar you can consolidate the images into one image. That would yield one image with lots of meteors.
Matt
At 10:52 PM 10/30/2001 -0800, Alson Wong wrote:
>I understand the benefit of using maximum aperture, but that also means that the exposures must be shorter before reaching skyfog. With ISO 800 film with p = 0.71 at f/1.8 and skyglow of mag. 20 per square arcsecond (roughly the amount of skyglow at our site), ASTREXP estimates an 11-minute exposure for reaching skyfog. At f/2.8, it's 40 minutes, and at f/4 it's 1.8 hrs. Thus, going one stop from 1.8 to 2.8 allows the exposure to be almost four times as long, and going to f/4 almost ten times as long, so I'm wondering if I can make up for the reduced aperture and reduced ability to record faint meteors by exposing for a much longer time before reaching skyfog. I would not have the faint meteors, but I'd get more bright ones because of the longer exposure.
>--
>Alson Wong
>Riverside Astronomical Society
> <http://www.rivastro.org/>http://www.rivastro.org/
>Visit my Web page at:
> <http://home.earthlink.net/~alsonwong/index.htm>http://home.earthlink.net/~alsonwong/index.htm
>
>----- Original Message -----
>
>From: <mailto:reeves10@swbell.net>Robert Reeves
>To: <mailto:astro-photo@seds.org>astro-photo@seds.org
>Sent: Tuesday, October 30, 2001 7:52 PM
>Subject: Re: [APML] Meteor Photography Questions
>
>There are a number of factors involved in successful meteor photography, and most of them are compromizes. Stopping down your lens will rob you of the ability to record many meteors. You need maximum aperture. Also, wide angle lenses may increase sky coverage, but their smaller apertures limit the number of meteors you can record with a given film. These and other factors are addressed on my web site at <http://www.robertreeves.com/metphoto.htm>http://www.robertreeves.com/metphoto.htm
>As for films. personally I'm going to a dark sky site and use Superia 800.
>
>Robert Reeves <mailto:reeves10@swbell.net>reeves10@swbell.net
>520 Rittiman Rd. <http://www.robertreeves.com>www.robertreeves.com
>San Antonio, Texas 78209 210-828-9036
>USA 29.484 98.440 200 meters
--
Matt BenDaniel
http://starmatt.com
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