How Do You Know If The Third Party Lenses You Buy Have The Ability To Resolve All Those Pixels On Your New Sensor?

This image has a little bit of everything: color, contrast, texture, shape, line, symmetry and
historical interest.  This is part of an 18th century wooden wall in Colonial Williamsburg, VA.
Notice the lap joint in the center just below the window frame.  Very unusual. (click to enlarge)

Third party lenses are typically great bargains these days.  There have been significant improvements in optical performance, build quality, autofocus and electronic connectivity over the past decade.  They are also normally less expensive than lenses manufactured by the large camera companies.  So what's not to like?

When you buy third party lenses for your digital camera, how do you know if those lenses will resolve all the detail your sensor can produce?  If you have one of the recent cameras with higher resolution sensors, do the third party lenses (some of the camera manufacturer’s lenses also) manufactured have the ability to resolve all of those pixels you so dearly paid for?  This may not matter to some photographers but others spend a lot of money for a camera with the latest, best and highest resolution sensors and they expect the lenses they buy to be able to capture all of that minute detail.  Does it matter to you?

In the past few years there has been an explosion of third party lenses for virtually all of the major camera brands.  You still have the 'big' four,' which I consider as Sigma, Tamron, Tokina and Voigtlander.  They have been around for decades and have proven themselves as producing excellent lenses over the years.  Most of the others, and they seem to multiply like rabbits, are seemingly from various Asian countries.  It seems every week there is a new lens manufacturer and the introduction of new lenses.

Again, my question to you is when you buy a Samyang, TTArtisans, Laowa, Rokinon, Yongnuo, Viltrox, 7Artisans, Meike, Astrahori, Brightin Star, Artralab or numerous other brands for example, how do you know that the lens you purchase will render all of the detail created by your digital sensor?  I think this question is especially critical if you have one of the newer high megapixel cameras with a sensor ranging from 33mp to 61mp.

As the matter goes, how do you know your camera's manufacturer's lenses can render all of that precious detail we love so much, especially if you are using lenses made several years or a decade ago during your DSLR days?  Do you know if your older Canon lenses can render 50mp?  Will those early Sony lenses render 61mp?  How about your F mount Nikon lenses rendering 47mp?  All of those older lenses were conceived, engineered or manufactured long before today's high pixel count sensors have been introduced in the marketplace.  At least with Fujifilm, they published a list telling us which of their lenses can "take full advantage" of their new 40.2mp cameras.  I don't know if the other manufacturers have published a similar list for their lenses.  If so, please leave a comment.

But you say, "I've looked at my images 200% and they are sharp!"  Sharpness, contrast and resolution, although interrelated, are different animals.  You can have a lens that sharply focuses a subject but cannot produce really high resolution images.  You can also have a highly resolving lens that is sloppily assembled and won't focus as accurately as it should, especially with today's autofocusing systems.  Contrast also plays a role in being able to discern subtle tonalities and fine separations between tiny details.

We rely on Modular Transfer Function (MTF) graphs to give us information on these three parameters.  However, you need to understand that the MTF graphs published by lens manufacturers are 'theoretical,' computer generated graphs, not graphs made from real world photographs.  There is nothing wrong with that and they can still serve as a comparison among lenses.  Also, the use of 10 line pairs/millimeter (lp/mm) and 30lp/mm seem kind of outdated?  Those particular measurements haven't changed in ages.  Those parameters were chosen long before digital photography and computer designed lenses were made.  Those two levels of performance may have served well with the lenses in the days of film, but are they really high enough for today's extraordinarily good lenses on high pixel digital sensors?  I'm not an expert so I'm speculating here.  Is it time to update the MTF charts so better serve modern digital lens manufacturing?  Just asking?

Lastly let me be clear.  I'm not saying these third party lenses are not good, can't render sharp images or cannot resolve all of the pixels on a high pixel sensor.  Many photographers seemed to be thrilled with them.  But how do you know the resolution capabilities?  

I've only bought one of the third party (Korean) lenses for one of my 26mp Fujifilm cameras a few years ago.  Evidently, one of the lens elements was out of alignment and that at infinity, the left half the frame was in sharp focus but as you moved away from center on the right side of the frame, the sharpness became worse and worse.  I sent it back.  I haven't bought any since.

I am interested in these third party lenses.  As I said, they can be one heck of a bargain.  Because of my interest I do read and watch reviews of these new, relatively inexpensive lenses and, it seems to me Viltrox keeps hitting home runs with their lenses.  Others, also, make lenses that review well.  I'll continue to watch what these companies produce and potentially consider one in the future, if I can figure out its resolution capabilities.

All of this is just something for you to think about before you purchase your next lens, food for though, so to speak.  Nothing more.

Join me over at my website, https://www.dennismook.com.  

Thanks for looking. Enjoy!  

Dennis A. Mook  

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