Results 1 to 17 of 17

Thread: Basic question: Difference between f5.6 and f2.8 and ISO

  1. #1

    Default Basic question: Difference between f5.6 and f2.8 and ISO

    Just wondering if I use a 400mm f5.6 and get a ISO of 1600. If I use a 400mm f2.8, what ISO will I get? I tried googling but they don't seem to give exact relationship.

  2. #2

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    The wonder of DSLR is the ability to set the setting MANUALLY according to situation. ISO is the sensitivity of the sensor and it is independant variable.

  3. #3
    Moderator catchlights's Avatar
    Join Date
    Sep 2004
    Location
    Punggol, Singapore
    Posts
    21,902

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    you should google, "from f2.8 to f5.6 is how many stops?"
    Shoot to Live, Live to Shoot
    www.benjaminloo.com | iStock portfolio

  4. #4

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    your question has nothing to do with focal length.

    you should take it out of the equation.

    if you don't understand what ISO, Shutter Speed and Aperture do, and how they function, no matter how much we explain to you, you'll never get it.

    go wiki

  5. #5
    Member jas1984's Avatar
    Join Date
    May 2011
    Location
    Singapore / Little Red Dot
    Posts
    475

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Try this... it help me under what is shutter speed and DOF...

    http://froknowsphoto.com/beginners/

    Hope this help...
    Nikon D5000 - 18-55mm l 55-200mm l 35mm f1.8g l Grip
    My FlickR l Google+

  6. #6

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Holding everything constant? For example if I shoot at a point using 400mm f5.6, I get ISO 1600 when using aperture of f5.6. When I shoot at the same point using 400mm f2.8, will I get ISO 400 when using aperture of 2.8 (because of the 2 stops difference?)

  7. #7

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by maisatomai View Post
    Holding everything constant? For example if I shoot at a point using 400mm f5.6, I get ISO 1600 when using aperture of f5.6. When I shoot at the same point using 400mm f2.8, will I get ISO 400 when using aperture of 2.8 (because of the 2 stops difference?)
    You know, you could always just test it and see...
    Alpha

  8. #8

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    The problem is I do not own a 400mm f2.8.

  9. #9

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Auto ISO?

    all things constant... not really. you didn't state the shutter speed. if your shutter speed stays the same, then yes,your ISO will be 400

  10. #10

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by maisatomai View Post
    The problem is I do not own a 400mm f2.8.
    As stated, it's not dependent on focal length. You can run the same tests with any lens that can hit f/2.8
    Alpha

  11. #11

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    sorry ts for asking here
    can i ask abit ISO, it "stop" count is it in this way?
    100, 200, 400, 800, 1600, 3200, 6400, 12400

    should i use on this few stop or can i use some in between? etc 640?
    Canon| Tokina(UWA) | newly added a Tamron(walkabout)

  12. #12

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by kelchew View Post
    sorry ts for asking here
    can i ask abit ISO, it "stop" count is it in this way?
    100, 200, 400, 800, 1600, 3200, 6400, 12400

    should i use on this few stop or can i use some in between? etc 640?
    You can use whatever ISO is needed for your shot, and do not need to be limited to the full stops.
    Alpha

  13. #13

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by Rashkae View Post
    You can use whatever ISO is needed for your shot, and do not need to be limited to the full stops.
    thanks for the reply..
    Canon| Tokina(UWA) | newly added a Tamron(walkabout)

  14. #14

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by maisatomai View Post
    Just wondering if I use a 400mm f5.6 and get a ISO of 1600. If I use a 400mm f2.8, what ISO will I get? I tried googling but they don't seem to give exact relationship.
    On the long term, it will be helpful if you read up on exposure.
    For the short term, f5.6 down to f2.8 is 2 stops.
    So from ISO1600 down 2 stops its 1600 > 800 > 400
    As mentioned above, the easiest way is just to play with the settings with your camera and any lens that goes to f2.8.




    Quote Originally Posted by kelchew View Post
    sorry ts for asking here
    can i ask abit ISO, it "stop" count is it in this way?
    100, 200, 400, 800, 1600, 3200, 6400, 12400

    should i use on this few stop or can i use some in between? etc 640?
    You can set it in the camera to use 1 stop; 0.5 stop; 0.3 stop increments.
    Last edited by pinholecam; 13th September 2011 at 02:20 PM.

  15. #15

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    You can set it in the camera to use 1 stop; 0.5 stop; 0.3 stop increments.[/QUOTE]

    thanks didnt notice that can change.. think i didnt explore my cam enough..
    Canon| Tokina(UWA) | newly added a Tamron(walkabout)

  16. #16

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    last time when pple learn to shoot with SLR.

    they will use 1 paper with few columns to jot down Fstop, ISO, S.Speed for each of the image they took
    they will mount a tripod, shoot the same images many times by vary the different 3 factors
    i think newbies should do that, cos when i learn to shoot DSLR 5years back, my instructor insist all of us should shoot with film camera

    pls go search bryan peterson in youtube
    see all his videos from 1 - xXx
    Last edited by soeypixels; 13th September 2011 at 04:41 PM.

  17. #17

    Default Re: Basic question: Difference between f5.6 and f2.8 and ISO

    Quote Originally Posted by maisatomai View Post
    Holding everything constant? For example if I shoot at a point using 400mm f5.6, I get ISO 1600 when using aperture of f5.6. When I shoot at the same point using 400mm f2.8, will I get ISO 400 when using aperture of 2.8 (because of the 2 stops difference?)
    if everything being constant, then yes, u r right. but it is not correct to say u will get iso 400, because either u set iso to 400 or u use auto iso and for auto iso, i am not sure if your camera will set it to iso400.

    but exposure wise f2.8 with iso400 = f5.6 with iso 1600 when the shutter speed remains constant for both cases.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •