Re: the mag the Sony 4 lux camera is capable of seeing

From: Tom Wagner (sciteach@mchsi.com)
Date: Wed Jun 04 2003 - 14:16:39 EDT

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    Björn  said, "If I remember correctly, my five year old Sony Hi-8 has a
    rating of 0.7 lux in normal mode."
    
    The 4 Lux for my camera sounded too high to me too. I got it from the
    technical specifications. Like Willie said the 0 Lux means that the built in
    infrared light makes it possible to shoot in total darkness (up to a couple
    meters anyway).
    
    I plan to try to adapt my video camera to my night vision scope. That may
    get down to magnitude +8 or so.
    
    Tom  Iowa  USA
    
    ----- Original Message ----- 
    From: "Björn Gimle" <b_gimle@algonet.se>
    To: "Tom Wagner" <sciteach@mchsi.com>; <SeeSat-L@satobs.org>
    Cc: "Astronomer" <Astronomer@yahoogroups.com>
    Sent: Wednesday, June 04, 2003 4:03 AM
    Subject: Re: the mag the Sony 4 lux camera is capable of seeing
    
    
    One number doesn't confuse me - Magnitude is 2.5 * 10-LOG(Brightness)
    Or Brightness = 2.512^Magnitude
    LOG(100)=2, so 100*  = 5 mag
    2.5*LOG(16) = 3.01
    2.512*2.512*2.512=15.85
    
    But lux ratings do: If I remember correctly, my five year old Sony Hi-8,
    which my children now use, has a rating of 0.7 lux in normal mode (there
    is no NightShot) and at max optical zoom (12*?) I got ten stars in the
    Pleiades, and at least three Jovian moons.
    
    Since then, most cameras boast "0 lux"! (<0.5?)
    
    An article in S&T Feb-2003 compares Meade Electronic Eyepiece ($70, no
    lux rating), PC164C ($130, 0.0003 lux), PC165C ($230, 0.05 lux) and
    StellaCam-EX ($700, 0.005-0.000005!) - and uses different scopes,
    different subjects and different exposures to compare (!) some results.
    
    Rainer Kracht uses an integrating Mintron 12V1C-EX and lens f=75mm f/1.3
    to get satellites down to +12.
    Greg Roberts' 1004x gives him satellites down to +8.3 with 0.003 lux and
    an 82 mm f/1.6 lens.
    Several messages on SeeSat-L (and DSat).
    
    With 11-inch scope and 0.0003 lux, S&T only got to mag +10
    
    /Björn
    
    ----- Original Message ----- 
    From: "Tom Wagner" ...
    > etc. I did some starlight magnitude tests with my Sony digital video
    camera
    > [DCR TRV 340]. Following are the results.
    >
    > The lens setting was 50 mm, F 2.4 at 20X magnification.
    > The imaging device is a 1/6", 460K gross pixels CCD.
    > The video was actually 290K Pixels.
    > The minimum illumination capable of being perceived is 4 Lux
    > Using the so-called "NightShot" mode I could barely see a star that was
    mag.
    > +3.
    > Using the "Super NightShot" mode I could barely see a star that was
    mag. +6.
    ...
    > According to Sony the Super NightShot mode is about 16 times brighter
    than
    > straight NightShot.
    >
    > Now can someone tell me how 16 times correlates to 3 magnitudes in
    > brightness?
    >
    
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