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Photography Question 

~Shehnshah H. Saleem
 

The Number Game!


I have a Sony DSC-P200 (7.2 MP) and on the large, I love it.

however, I have been reading some of the posts and articles here and was motivated to using the M-anual mode and learn that for myself. After reading many posts, Q&A discussions and forums on this site and others I still find myself confused between ISO, f-number (1, 2, 3, 7, infinity, auto), shutter speed (30 seconds to 1/1000 second), and aperture.

my main problem is with the aperture. apparently at any level of zoom I can only select between any two given apertures. is that the way it is supposed to be? furthermore, if someone could explain the rest of the numbers to me in relatively EASY to understand language and usage I shall be very grateful. many thanks.


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February 12, 2006

 

Andrew Laverghetta
  No, you have many many different apertures to choose from. The time when this changing of apertures comes in to play, and is tied to the focal length (level of zoom), is when you are trying to use the cameras widest aperture. Some zoom lenses can't hold the same wide aperture through the whole zoom range so this is when you will see something like f/3.5-4.5 or something like that. The size of the aperture doesn't actually change, it just doesn't let in as much light.

ISO stands for something that I think is along the lines of International Standard of Organization. That's basically the sensitivity of a piece of film or the digital sensor to light. The most common lower ISO speed on films and digital cameras is 100 and then the number doubles as the sensitivity doubles. ISO 200 it twice as sensitve to light as ISO 100 so you can use either a faster shutter speed, a smaller aperture, or a combination of the two. So up from ISO 200 there's 400, 800, 1600, and possible 3200. These change with cameras and different films.

Then with apertures, the larger ones are the lower numbers, and the smaller ones are the larger numbers. So..f/2.8 is a larger aperture than f/22. I believe that the normal f/stops (numbers that denote how open the aperture in the lens is) are 2.8 4.0 5.6 8.0 11 16 22 and 32. Some other lenses will go larger or smaller but they're usually more specialized and not usually a zoom lens.

As for shutter speed, 30 second to 1/1000 second means that that would be the extremes of shutter speeds so 30 seconds (cut that in half and you get) 15 seconds (cut that in half and you'll get around) 8 seconds and so on. If you wanted to go the opposite way from 1/1000, a longer shutter speed would be 1/500, and then 1/250, 1/125 and so on. Many cameras will have "half-stop" increments or "third-stop" increments which will let you get closer, generally, to the best exposure. There are also many other books on basic exposure that will help. Do a betterphoto.com seach in the search box (top left) on "basic exposure" or something like that. There are also a lot of books on the subject, but I'm not going to give any specific books plugs because the same book, while probably good, is always brought up.

Hope this helps!

-Andrew


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February 12, 2006

 

~Shehnshah H. Saleem
  Thank you for your thorough response. I still do not understand the "many many different apertures to chose from" that you mentioned. I realise that there are different ones, as I mentioned for any given level of zoom it only provides me with TWO options.

e.g. at
1x I have 2.8 or 5.6
1.3x I have 3.2 or 5.6
2.4x gives me an option between 4.5 or 9

is that the way it is supposed to be? and is that what you were referring to when you said that there are many options but they are tied to the focal length?

many thanks.
~SS


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February 13, 2006

 
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