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December 20, 2006
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ISO/Aperature Answer

Wed Dec 20, 2006, 11:02 AM
  • Mood: Content
  • Listening to: Nickleback
  • Reading: Complete Guide To Night & Low-Light Photograph
  • Watching: my back
  • Playing: with my backup camera
  • Eating: Nothing (yet)
  • Drinking: Cop coffee


So things here are almost back to the norm.  We now have power and we will have cable/internet tonight, I hope I hope.  So if I don't get back to you right away you know the reason.
The answer to my question, is a 2 parter found in a book called, "The Complete Guide To Night & Low-Light Photography" by Lee Frost from Amphoto Books.  The process is call backtracking but it was more like forwardtracking for what I wanted to do.

The exposure is being doubled each time you halve the film speed.  So, if your camera meter gives an exposure reading of 15sec at f/4 on ISO3200, at ISO100 the correct exposure will be 8min at f/4 (15sec at ISO3200, 30sec at ISO1600, 60sec at ISO800, 120sec at ISO400, 240sec at ISO200 and 480sec at ISO100).

Now this part works for me like this: D70s (Tyra) exposure setting of 30sec at f/22 on ISO200, at ISO50 Coolpix 8700 (Holley) the correct exposure will be 120sec at f/22 (30sec at ISO200, 60sec at ISO100 and 120sec at ISO50).  

Captin' I'm givn her all I got and she will not do f/22.

Getting to the aperture you want to use by doubling the exposure each time you move to the next f/stop. Example: You get a reading of 20sec at f/4 but want to take a pix at f/16.  At f/16 the correct exposure would be 5min 20sec (20sec at f/4, 40sec at f/5.6, 80sec at f/8, 160sec at f/11, 320sec at f/16).

My Coolpix (Holley) will not do the f/22 I want to use but will do a f/8 and a ISO50 that the D70s (Tyra) can't do.  Using the answer from above or before, "ISO50 120sec at f/22", this is how this works for me: The correct exposre will be 15sec at f/8 on ISO50 (120sec at f/22, 60sec at f/16, 30sec at f/11 and 15sec at f/8).

Or I could have just read the post from ~souk1501, ~neurophonix and ~ShannonReiswig or used the link the ~cappaholic posted.  Still I had fun learning this and going old school with new tools.

Now you know what I know and thats one to grow on YO JOE  --- Que GI Joe music.  I think I just dated myself with that joke...  

Thank everyone for helping with this one.

Proud Member of:
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:iconesteficita:
Oh no, I miscalculated... Well, there is a reason why I didn't become a rocket scientist, but a language person.
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:iconurbanrural-photo:
~UrbanRural-Photo Dec 27, 2006  Hobbyist Photographer
Took me 2 weeks to get it, so don't feel bad.
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:iconhellfirediva:
`hellfirediva Dec 20, 2006  Professional Photographer
Wow thanks for that one Shelly , interesting !!!
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:iconurbanrural-photo:
~UrbanRural-Photo Dec 21, 2006  Hobbyist Photographer
You are very welcome
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:iconart-photo:
Thanks for sharing the knowledge. :nod:
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:iconurbanrural-photo:
~UrbanRural-Photo Dec 20, 2006  Hobbyist Photographer
No problem. Sharing is caring. More to come.
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:iconsouk1501:
haha, it's always fun to figure things out. I am glad I could help. =)
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:iconurbanrural-photo:
~UrbanRural-Photo Dec 20, 2006  Hobbyist Photographer
It was a blast and thank you.
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