focal length qualities.

Discussion in 'Photography Beginners' Forum' started by iknowdatalfabat, Aug 7, 2008.

  1. iknowdatalfabat

    iknowdatalfabat TPF Noob!

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    i've been told that prim focal length lenses are sharper and better quality than zooms. does this mean that a zoom with less focal lengths covered (e.g. 24-120 vs. 18-200) is better quality than one with more focal lengths.
     
  2. usayit

    usayit No longer a newbie, moving up!

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    Its just a general statement that is often tied to the complexities required.

    Prime focal length lenses (single focal length) are simple in design and thus can be optimized for a particular focal length. This generally means better image quality but you are stuck with just a single focal length.

    Zooms are more complex in design to provide a range of focal lengths. Compromises have to be made... thus ~generally~ compromises in image quality but you have the convenience of a range of focal lengths.

    Superzooms that establish a very wide range of focal lengths are a step further. The design incorporates even more compromises but you have even wider range of focal lengths.

    Remember.. this is just generalities.... For those that want to focus on IQ above all else will shoot primes and carry 4+ lenses. Those that want to carry a single lens to cover almost every possible subject... carry superzooms. Those that want to balance will carry a shorter ranged zoom and perhaps carry 2.
     
  3. iknowdatalfabat

    iknowdatalfabat TPF Noob!

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    ohh ok. is the image quality differences noticable?
     
  4. usayit

    usayit No longer a newbie, moving up!

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    No way to answer unless you test in specific controlled environment with specific lenses which is pointy to the pointless..


    For me with my lenses and my observations, I can see a difference.
     
  5. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    USAYIT has outlined the basics of the arguments surrounding zooms and primes - and the statment that the difference is noticable is backed up a lot by experienced photographers.
    However many of these same photographers will also use zooms - convenience and weight and space (As well as cost) are all factors to consier.
     
  6. TamiyaGuy

    TamiyaGuy No longer a newbie, moving up!

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    I agree with USayIt, there really isn't a way to test if the image quality differences are noticable. Different superzooms have differing quality; a £150 third party lens is bound to have worse quality than a £450 home-brand lens, although you may or may not be able to tell the difference.

    Of course, this doesn't mean that you should get 12 prime lenses. Zooms can still be of VERY high quality (a home-brand 70-200 f/2.8 is a good example of this), and often their versatility outweigh their suffering in image quality. However, it's still very useful to have a prime lens or two in the kitbag (a 50mm 1.8 is a good choice), as primes usually have a faster maximum aperture and, when stopped down, give fantastic sharpness.
     
  7. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Although primes are often a smidge sharper and do a better job resolving very fine detail than zooms, that's never the reason I choose to use them. The main reason I'd choose a prime lens over a zoom is max aperture (or at least anything faster than f/2.8).

    Most modern zooms are very sharp. More than sharp enough for any of my needs. If there are softness issues with a photograph I look to operator error first. Assuming the lens isn't a lemon, it's almost always a problem with the photographer rather than the lens. As I brought up in the other thread, if you consider perspective important to composition, then the cropping/increased enlargement that may be necessary when restricted to a single focal length can easily eliminate any edge in sharpness.

    Super zooms are very complex, and I guess I'd expect them to have more optical issues than smaller zooms and primes. I haven't used one since they first showed up in the late 90s. I had a Pentax 28-200. I never noticed any sharpness problems, but at that time there was more than enough other stuff wrong with my photos to be worrying about. :)

    In the end each photographer must carefully assess the lenses they are using individually. I've found that the variances in quality in the same lens model line are often just as great as between completely different brands, and the differences in technique and style between photographers is even greater and of significantly more influence on the technical image quality of the finished photograph. Gear that one photog finds impossible to use may work wonderfully for the next.
     

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