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Zoom lenses and aperture question
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<blockquote data-quote="Eye-level" data-source="post: 49211" data-attributes="member: 6548"><p>OK I will give it a shot...in a nutshell fixed aperture lenses are way more sophisticated, typically use a "more" special ground glass, and the elements tend to be much larger than the ones used in variable aperture lenses (hence their greater size and weight), and finally they typically contain "special" types of elements. On many modern zoom lens mounted to digital cameras you are able to fix the aperture as long as it stays within the range of the lens...eg you have a 4-5.6 lens you can find an option in one of your camera menus and set the fixed aperture at F4 you can then zoom the lens in or out and it will stay at F4 the trade off is that you lose optical quality the further out you zoom where with the variable aperture it is optimized to perform how it performs at the various zoom ranges according to it's lens formula. (A high dollar fixed aperture lens typically has so called floating elements which change position as the lens is zoomed in or out thus maintaining the light at the sensor at a constant strength. Floating elements are much harder to manufacture and thus way more expensive. Edit they are not really floating elements but they are special and there also tend to be more of them in fixed aperture lenses)</p><p></p><p>So basically what that means is that it is not so much the physics of the lens per se (athough that is of utmost concern to the lens designer) but has more to do with cheaper and faster manufacturing process.</p><p></p><p>Now let's look into the very near future...lens grinding technology and computer aided lens formula design is progressing by leaps and bounds so what will probably happen is they will be able to make these variable aperture lenses perform better and better until they are just as good as a fixed aperture lens. Leica and Nikon and Canon are already making very very good variable aperture zooms and one day we can probably expect all zoom lenses to be made this way.</p><p></p><p>It is a very similiar situation with regard to fixed focal length lenses...the new formulas and new coatings are making for better lenses...</p><p></p><p>Everything is computers now...think about how much more efficient modern day cars are...it is because the engines are computer designed for optimum performance but they still burn the same old gas.</p></blockquote><p></p>
[QUOTE="Eye-level, post: 49211, member: 6548"] OK I will give it a shot...in a nutshell fixed aperture lenses are way more sophisticated, typically use a "more" special ground glass, and the elements tend to be much larger than the ones used in variable aperture lenses (hence their greater size and weight), and finally they typically contain "special" types of elements. On many modern zoom lens mounted to digital cameras you are able to fix the aperture as long as it stays within the range of the lens...eg you have a 4-5.6 lens you can find an option in one of your camera menus and set the fixed aperture at F4 you can then zoom the lens in or out and it will stay at F4 the trade off is that you lose optical quality the further out you zoom where with the variable aperture it is optimized to perform how it performs at the various zoom ranges according to it's lens formula. (A high dollar fixed aperture lens typically has so called floating elements which change position as the lens is zoomed in or out thus maintaining the light at the sensor at a constant strength. Floating elements are much harder to manufacture and thus way more expensive. Edit they are not really floating elements but they are special and there also tend to be more of them in fixed aperture lenses) So basically what that means is that it is not so much the physics of the lens per se (athough that is of utmost concern to the lens designer) but has more to do with cheaper and faster manufacturing process. Now let's look into the very near future...lens grinding technology and computer aided lens formula design is progressing by leaps and bounds so what will probably happen is they will be able to make these variable aperture lenses perform better and better until they are just as good as a fixed aperture lens. Leica and Nikon and Canon are already making very very good variable aperture zooms and one day we can probably expect all zoom lenses to be made this way. It is a very similiar situation with regard to fixed focal length lenses...the new formulas and new coatings are making for better lenses... Everything is computers now...think about how much more efficient modern day cars are...it is because the engines are computer designed for optimum performance but they still burn the same old gas. [/QUOTE]
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