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Noob question - focal length vs aperture
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<blockquote data-quote="Rexer John" data-source="post: 126459" data-attributes="member: 12691"><p>You are correct sir.</p><p>Except where you say the aperture is fixed at 2.8</p><p>The aperture size may well be the same size at 70mm as it is at 200mm.</p><p>The f number is how much light is getting through the lens. It's not the diameter of the aperture but it is the relative aperture.</p><p>So your relative aperture will be less at 200mm, even though the aperture is still the same size.</p><p>Set the lens to 200mm and set the aperture as wide as possible, the f number will be displayed in your viewfinder.</p><p>Remember that's not the aperture but the lenses light gathering capability at that zoom setting expessed as a number (f).</p><p></p><p>P.S. If you can get down to 2.8 at 200mm I'm guessing the aperture is able to open further at longer zoom to maintain the same f number.</p><p>Someone more knowledgeable than me will reply soon.</p></blockquote><p></p>
[QUOTE="Rexer John, post: 126459, member: 12691"] You are correct sir. Except where you say the aperture is fixed at 2.8 The aperture size may well be the same size at 70mm as it is at 200mm. The f number is how much light is getting through the lens. It's not the diameter of the aperture but it is the relative aperture. So your relative aperture will be less at 200mm, even though the aperture is still the same size. Set the lens to 200mm and set the aperture as wide as possible, the f number will be displayed in your viewfinder. Remember that's not the aperture but the lenses light gathering capability at that zoom setting expessed as a number (f). P.S. If you can get down to 2.8 at 200mm I'm guessing the aperture is able to open further at longer zoom to maintain the same f number. Someone more knowledgeable than me will reply soon. [/QUOTE]
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Noob question - focal length vs aperture
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