[AZ-Observing] Re: Latest photos: planets, Iridium flares, ISS/shuttle pass, etc.

  • From: Joe Orman <joe.orman@xxxxxxxxxxx>
  • To: az-observing@xxxxxxxxxxxxx
  • Date: Sat, 14 Jul 2007 16:24:07 -0700 (PDT)

  Yes, Provia 100F is ISO 100.  This is fairly slow film; when shooting Iridium 
flares from the city you don't want to overexpose the light-polluted sky or the 
foreground (as the captions to my photos stated, the houses were illuminated by 
a street light).  But you need to keep the shutter open long enough to capture 
the entire flare.  So based on previous experience with night photos in my 
neighborhood, I came up with a baseline exposure of f/4, 60 seconds (ISO 100 
film). The time given on heavens-above is for the MIDPOINT of the flare; you 
have to open the shutter 20 to 30 seconds before that (I keep my digital watch 
set within a second of the correct time). Another fun challenge is planning the 
composition in advance using the predicted altitude and azimuth of the flare -- 
aligning the camera, an appropriately-facing house and the flare location 
(remember, I'm opening the shutter BEFORE the flare becomes visible).  I 
typically use a 40mm lens -- wide enough to keep
 everything in focus, minimize trailing, and give enough margin of error so the 
flare will actually be in the frame!
   
  Here are examples of Iridium flares photographed in very dark skies:
  http://joeorman.shutterace.com/Meteors/Meteors_070315_32.html
  http://joeorman.shutterace.com/Meteors/Meteors_010624_10.html
  Under these conditions, you don't have to worry about overexposure, and you 
can use much faster film, but you need to keep the shutter open longer (~ 2 
minutes) since the faint "tails" of the flare will show up (notice the star 
trailing in the untracked image).
   
  I hope these tips are helpful -- if anyone takes any good flare images, I'd 
enjoy seeing them.
   
  --Joe 
  
Jimmy Ray wrote:
  Hi Joe,

(oh,oh here comes the nubie with his camera again) Love the way those flares 
turned out. Couple of questions. Am I to assume the 100F slide film means 
ISO100? Is there a street light or other close illumination in front of your 
house? I've done a couple of "flares" but no where as neat as yours. I went 
for a very small section of sky and 30 seconds. Trailing and focus being the 
detriment of those images. At 60 seconds yours look spectacular.

Jimmy Ray


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