Monday, August 13, 2012

What Is Acceptable Optical Quality?

Many people, including some readers of this blog, find the NEX kit lens 18-55mm and the 16mm f2.8 lenses to be optically unacceptable.  Yet, many, including me, find these lenses optically acceptable, given the price point.  What constitutes lens quality as acceptable?  Obviously, everyone has their own level of acceptance.

Optical quality is more than just sharpness. Distortion is probably the biggest concern for many people after sharpness.  Then there are other aspects such as vignetting, colours, rendering style, bokeh, flare resistance, and possibly others that affect our perception of optical quality. Personally, I think I have a pretty low standard of optical quality acceptance, when price of the lens is weighted it.  I am easily satisfied.  You might think that after using so many lenses, I would become a lens snob, but that's not true at all.  I always evaluate a lens from its target audience.  One should not expect the same optical quality from a kit lens from those that costs a thousand dollars or more.

Glass Stairs - NEX-5N & E-16mm f2.8. Click for larger.

In the case of the Sony 18-55mm kit lens for NEX, it's on par with most other manufacturer's kit lenses, though I think the original Panasonic 14-45mm (metal mount) is one of the best kit lenses I have used, but they all have their short comings, especially in the distortion department.  Manufacturers are increasingly relying on in-camera correction for lens design flaws.  I think this is a bad trend, especially when you are paying hundreds of dollars for a nice prime lens; you want a lens that's well designed from the beginning, not a patch up job by software afterwards.

Different kinds of horses - NEX-5N & E-16mm f2.8. Click for larger.


  1. Well, the 16mm is actually very sharp in the center but quickly gets soft towards the corners and is never really sharp across the frame at any aperture.

    The 18-55 I suppose is ok for a kit lens. It really is quite sharp but as you say, the distortion at the wide end is distracting and at the long end it's only f/5.6. For someone who is used to shooting with 50/1.4 lenses, this alone is a reason to frown.

    But the real reason why I don't like these two lenses is purely subjective. The photos I make with them just don't look as nice to me. Maybe this could be empirically and scientifically proven but most probably it's just in my head. Though I'm not a lens snob either. Quite the opposite, I would think. ;)

    1. Hehe, I hear you. There are lenses I don't use much, not because they are bad, it's just because they don't seem to appeal to me :)

  2. I think it is easy to forget one big advantage with the 18-55 lens and that is optical image stabilization and autofocus.
    Given those two features it is a very good lens, because you get sharp pictures, pictures that would have been blurry and/or unsharp if taken with a regular manual focused lens without OSS.


    1. Definitely. OSS is one of the best features, but I do wish it was in-body stabilization instead of in lens.