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Re: (meteorobs) Normal lens
In a message dated 97-03-21 11:49:46 EST, you write:
<< e: Catagory "B" : Normal lenses, with F-ratios of F-1 to F-3.5 and focal
lengths of 50mm, (the normal 35mm lens) to 200mm, (the common aero camera
lens)
Both standard 35mm cameras and aero cameras fall into this catagory.<<
Oh! Okay I see what you're saying now.
>>To get an aero lens, try placing a "Wanted to Buy" ad on the WWW on
ASTROMART or the ATM net. I think the correct address for posting an ad to
Astromart is: astromart-errors@listsdot best.com. That is how I got my F-2.5 -
12 inch focal length Kodak Aero Ektar for $125 US. There is another outfit
called surplus shack but I don't know the address off hand. You can place
an ad on the astro news groups also. I'm sure you will come up with some
aero lenses that way.<<
Thanks, this will help.
>>S. If you find a source of inexpensive <gratings> let me know!!! You
could try
cheap film replicas as an experiment but they won't be very efficient. It's
har enough to get a spectrum as it is. <<
Last year I noticed an ad in the Starry Messenger where someone was trying to
sell a 1 inch square grating..dot can't remember the cost now. but at the time I
thought it was too small of a piece to use.
>> I operate from my
backyard and can get away with 20 minute or so exposures before sky fog
becomes a problem. At a good dark sky site you can go much longer. If
you<<
Do you have any problems with getting too many interferring star spectra on
the negative after about 20 or so minutes?
George Zay