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Old Jun 9, 2010, 10:44 AM   #1
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Default Long but easy lense question

I will be buying an Olympus E-P2 and I am trying to figure out what lenses I need. The problem is is that I don't know what the millimeter range means (40mm - 150mm) and I don't know what the difference is in the focal number, or rather I don't know what it means for me. I know that F2.0 is refering to the size of the aperature and that deals with how much light let in but I don't know the difference between a lense thats F2.8 - F3.5 and one thats F4.0 - F5.6 and what its going to do to the photo.

I want lenses for lanscape, portraite, nature, and sport photography.Here are the lenses that I am considering right now for that perpouse:

M.Zuiko Digital ED 17mm F2.8 (one of the kit lense options) - because its small and I would be able to carry the camera in a pocket when I didn't want to take all my gear.

M. Zuiko Digital ED 14mm - 42mm F3.5 - F5.6 (the one with the big diaphram) - because it still small and easy to transport but will enable zoom.

M. Zuiko Digital ED 70mm - 300mm F4.0 - F5.6 - I think judging from the range of the mm numbers it means that this lense will give me a greater zoom and will be good for nature but do I want this lense or the next one?

M. Zuiko Digital ED 40mm - 150mm F4.0 - F5.6 - this lense should have a greater zoom, not as much as the 70 - 300, and could be good for nature and portraite photography and maybe even sports. But do I want to sacrifice zoom for the other attributes of this lense?

All of my information has come from the Olympus website lense selector.
(http://www.olympusamerica.com/cpg_se...sSelector_chip)

Thank you for bearing with me for this long and dealing with my lack of spelling knowlege. Any info or segestions you may have will be greatly appriciated as I obviously know nothing about lenses. I just know I want the E-P2.
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Old Jun 9, 2010, 11:14 AM   #2
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A very good explaination of Aperture is at http://en.wikipedia.org/wiki/Aperture#In_photography

The f-numbers (http://en.wikipedia.org/wiki/F-number) are the ratio of the diameter of the diaphram to the focal length. If you double the f-number, you get 1/4 as much light (f/8.0 lets in 1/4 as much light as f/4.0, which lets in 1/4 as much light as f/2.0) but the scale isn't linear. Midway between f/2.0 and f/4.0 is f/2.8, not f/3.0. (f/2.8 lets in twice as much light as f/4.0, which lets in twice as much light as f/5.6.)

The smaller (numerically larger) the aperture you use, the slower the shutter speed or the higher the ISO setting you must use to compensate for the lesser amount of light. But slower shutter speeds can cause motion blur and higher ISO settings can cause image noise.
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Old Jun 9, 2010, 11:23 AM   #3
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A good explanation of focal length is at http://en.wikipedia.org/wiki/Focal_l...In_photography

The "mm" number is the focal length of a lens, in millimeters, and is an indication of how wide an angle of view a lens gives. Shorter focal lengths give wider angles of view, and vice versa. But again, the relationship between the focal length and the angle of view isn't linear. For instance, in the 14-42mm lens, 42mm is 3X longer than 14mm, but the angle of view is only 2.6X narrower.

On the E-P2, a lens with a focal length of 11mm has an angle of view of about 90, so if you're standing in the corner of a room, you should be able to capture an image from one adjacent corner almost to the other. But a lens with a focal length of 25mm has an angle of view of abuot 45, and a lens with a focal length of 54mm has an angle of view of about 22.5.

That should give you some idea of how that all works.
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Last edited by TCav; Jun 9, 2010 at 11:37 AM.
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