Help reading shutter values..

BBstringerBBstringer Registered Users Posts: 101 Major grins
edited March 23, 2010 in Technique
I hope someone can help. I have a photo class assignment "low light" which requires bracketing + 1 stop, - 1 stop. Okay, so far so good. First (normal) shot is 7.1 @ 1.3, the second is 7.1 @ 1.6" (note the double prime) and the third is 7.1@ 2.5. I know I've accomplished a full stop over and under...I just can't figure out the values by the numbers represented. How is 1.6" twice the value of 1.3.....I'm lost here and any help would be greatly appreciated:dunno

Comments

  • RichardRichard Administrators, Vanilla Admin Posts: 19,962 moderator
    edited March 23, 2010
    BBstringer wrote:
    I hope someone can help. I have a photo class assignment "low light" which requires bracketing + 1 stop, - 1 stop. Okay, so far so good. First (normal) shot is 7.1 @ 1.3, the second is 7.1 @ 1.6" (note the double prime) and the third is 7.1@ 2.5. I know I've accomplished a full stop over and under...I just can't figure out the values by the numbers represented. How is 1.6" twice the value of 1.3.....I'm lost here and any help would be greatly appreciatedne_nau.gif

    Hi BB,

    I don't know what you're shooting with, but this has a simple explanation on a Canon camera. The numbers without the double prime are the denominators in fractions of a second, so 1.3 means 1/1.3 seconds. The double prime means seconds, so 1.6" means 1.6 seconds. 1/1.3 = .77 seconds, not precisely half of 1.6, but close enough for rock 'n' roll.

    HTH.
    My Pics
  • Scott_QuierScott_Quier Registered Users Posts: 6,524 Major grins
    edited March 23, 2010
    Wow - Richard, it took me three readings through both the OP and your explaination to understand the details of the question.

    @BBstringer - of course and just to be complete, 1/1.3 (0.77s) is approximately one stop slower than 1/2.5 (0.4s).
    Scott
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  • BBstringerBBstringer Registered Users Posts: 101 Major grins
    edited March 23, 2010
    Thanks a million guys. I finally found the numbers presented differently on a web site. Right...they showed the 1.3 as .8 seconds (right, close enough for rock 'n roll :-) I knew the double prime was seconds (the old cartography days arc seconds) that formula eluded me on the lower values. Anyway...I shoot a D300 but this was on my F5 (I know...FILM!!!!!) and I knew 1.3 had to some how represent half of 1.6 seconds....Ah, something new every day. Again, thank you for your help it's very much appreciated. :ivar
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