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EV; What is it and how does it work?

f5fstop

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"RE: EV"

f5fstop Awarded for his contributions to the Resources Basic Member
Sat 21-Jul-01 10:43 PM

I appreciate the offer Doug, but unfortunately, I don't have excel. Do you think it would work in the MSWorks spreadsheet?
Probably not…

I think I'm beginning to understand about exposure compensation but I'm not sure yet. If I want to take a picture and my camera meter says 1/250 at f5.6 and it has a dark background and say...I want to lighten the background...I open the aperture to f2.8. I just made an exposure compensation, right?
If you are in aperture priority and you open the aperture to F/2.8 from F/5.6, the computer will lengthen the shutter speed to maintain the same exposure, and the shutter speed will move two-stops to 1/60. This affectively gives you the exact same exposure as you had before you changed the aperture. However, if you use the compensation dial on your camera, the aperture will stay at F/5.6 since this is what you manually set it to, and the computer will vary the shutter speed by the exposure compensation you requested.
For example if you are in aperture priority mode, and you set the aperture to F/5.6, and the shutter is showing 1/250, and you compensate one stop over and one stop under exposure, the camera will take three photos. All photos will be at F/5.6 however, the over exposed frame will be at 1/125 (slower shutter speed…more light), the underexposed frame will be at 1/500 (faster shutter speed…less light) and the normal exposed frame is at 1/250.
Of course, you can shoot in full manual mode and adjust both the aperture and shutter speed to what ever you consider appropriate.


Now, did I just adjust it 1/3, 1/2 or what. Is each step on the aperture ring of my lens a 1/3 stop? How much of a "stop" is each change of shutter speed or does it matter depending on the ratio in the shutter speed steps? (i.e from 1/125 to 1/250 as opposed to 1/250 to 1/350 etc.)
The standard sequence of F-stops in one-stop increments is:
F/1.0 F/1.4 F/2.0 F/2.8 F/4 F/5.6 F/8 F/11 F/16 F/22 F/32 F/45 F/64

For half-stop increments: F/1, F/1.2, F/1.4, F/1.8, F/2, F/2.5, F/2.8, F/3.5, F/4, F/4.5, F/5.6, F/6.7, F/8, F/9.5, F/11, F/13, F/16, F/19, F/22, and so on…

The standard sequence for shutter speeds is:
8, 4, 2, 1, ½, ¼, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, and so on…


Hope this info helps.


Doug


--Take only photographs, leave nothing but footprints--


NC, second week of October, 2001...



"Take only photographs, leave only footprints"

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A general, generic topic EV; What is it and how does it work? [View all] , mbowker64 Silver Member, Fri 20-Jul-01 10:33 PM
Subject Author Message Date ID
Reply message RE: EV photodoc
21st Jul 2001
1
Reply message RE: EV f5fstop Awarded for his contributions to the Resources
21st Jul 2001
2
     Reply message RE: EV mbowker64 Silver Member
21st Jul 2001
3
          Reply message RE: EV f5fstop Awarded for his contributions to the Resources
21st Jul 2001
4