Lens quality

[armen_hovannisian]

<p>Does the lens quality (plastic, metal) affect the image quality ?</p>

[tommyinca]

<p>(FWIW, IMHO) I assume you mean lens bellow not the lens itself. No (in theory), it will work just as good if it is designed properly. Properly means there are enough internal structure so the lens elements and groups can be and do stay alighted over time, vibration and temperature. Properly also mean the designer put in proper flare suppressing light baffle that account for the different surface finish of plastic. Yes (in reality) because the use of too much plastic is the first sign of cost cuting. Chancing are there other cost cuting elsewhere that will hurt performance. </p>

[CoryAmmerman]

<p>In the strictest sense, no. The barrel of the lens is only a means of holding the individual pieces of glass in place within the lens and it doesn't matter what that is made of, as long as the glass all stays where it's supposed to be. Where the overall build quality comes in is in the reliability and ruggedness of the lens. Lenses made of metal, generally speaking, can absorb bumps and other minor mishaps better than plastic lenses. The image quality of a plastic lens may begin to suffer over time as compared to that of a metal lens, due to damage. As Tommy stated above, the quality of construction of the lens barrel is usually an indicator of the quality the parts inside, which is what you really need to be concerned with. </p>

<p>That being said, I have a 28-80 Nikkor G lens that is made almost completely out of plastic that I've been using for years and still gives very sharp images. Nikon cut costs in that lens by making it out of plastic (although it's <em>good</em> plastic) and by giving it a small and variable maximum aperture.</p>

[remco-jan.woldhuis]

<p>Note that high quality plastics and plastic structures can be better than metal structures. However, most plastic lenses are built for cost reductions. </p>

[andylynn]

<p>The actual plastic and metal does not affect the image quality. However, since the lenses are designed as a "package", budget lenses usually are made of mostly plastic and have inexpensive optics, and high end lenses usually are made of mostly metal and have better optics.</p>

<p>Don't let that discourage you. Some of the inexpensive plastic lenses are actually very good. For example, with Nikon, the cheapest lens - the 50mm f/1.8 - is fast and very sharp, is their smallest and lightest lens, and is often used by pros. The 18-55 VR kit lens is sharp and light and very good for taking photos in good light and when you don't need telephoto, and you'd be very hard pressed to see the difference in a photo from the 18-105 VR kit lens vs. the twice-as-expensive 16-85 VR lens they make for rich amateurs.</p>

[nathangardner]

<p>The part of the lens that affects IQ is the glass. Better glass produces better colors and more sharpness. With zooms, the engineering affects the IQ along with the glass, and you pay a lot of money for a great zoom. The cheapest way to get maximum IQ is to use primes. My $100 Canon 50mm 1.8 prime is sharper than my $700 17-40mm zoom. With primes you don't have to pay an arm and a leg to get good quality and you'd be hard pressed to see a big diference in IQ in a $300 prime and a $1500 prime. They're also the cheapest way to get a fast lens. A fast zoom with a max f-stop of 2.8 usually costs over $1000 (with the exception of a few 3rd party lenses).</p>