Sharpness Is Overrated

Introduction
A combination of conveniences relating to modern digital photography have led to a trend of hyper-scrutiny on lens performance, most notably sharpness. Nowadays we are blessed with data-dense raw files, and process our images on high definition, wide colour-gamut screens. We can also zoom into our images on-screen by hundreds of percent very quickly and easily, typically to check specific technical aspects (focus, depth of field, noise, coma etc), to refine complex selections, or to perform intricate local edits (e.g. brushwork on layer masks). Then we have the endless supply of “this lens vs that lens” videos on YouTube with their image comparisons where differences in sharpness are often barely visible, even when heavily magnified side-by-side. We also see a similar obsession on social media groups with the never-ending “how sharp is it” line of debate and questioning. Problem is, it is all too easy to take on board and carry across all this published scrutiny in the form of attitude and mindset to our own images, and become all micro-analytical and judgemental over how our lenses are performing on a pixel level. 

Admittedly, I quite enjoy zooming into my images on the screen now and again just to marvel at the level of detail lenses and sensors are able to resolve. It’s as though the geek in me can’t help but admire the cleverness of optical physics and design. However, does this change how I view my photograph as a piece of art? In fact, one of the best (in my opinion) landscape images I have ever made was taken using a plastic craptastic Nikon 18-55mm crop sensor kit lens under conditions (fog) where sharpness is, in any case, significantly curtailed by atmospherics. To this day I honestly have no idea where in the frame I focussed. Nevertheless, the atmosphere (vibe) and lighting in the image is what makes it, and the absence of “world class” sharpness does nothing to negate that. 

Indeed, when we look admiringly at history’s most famous and critically acclaimed photos where in the list of analytical criteria does “how sharp is it” honestly sit? Does sharpness impact what the photo makes us think, interpret and feel? Do we look at an Ansel Adams landscape image or a street photo by Henri Cartier-Bresson and wonder “if only they used a sharper lens”?  Yet, nowadays it seems that an alarming number of photographers are constantly looking to upgrade their lenses, usually at huge cost, based on differences that only an MTF chart could alert them to, seemingly forgetting or dismissing other optical traits that build a lens’ individual character. Objectively, sharpness makes up exactly nothing for a lack of compelling subject, composition and light, nor for a lack of anticipation and hence failure to fire the shutter at the critical moment. 

Sharpness: Help or Hindrance?

There are of course instances where a sharp lens is advantageous. This is not an exhaustive list, but is here merely to illustrate that sharpness does have its place and isn’t being dismissed completely.

Macro photography: the main job of a macro lens is to resolve fine details on small subjects at 1:1, life-size on the sensor/film plane. The vast majority of macro lenses are tack sharp for this specific purpose. Given their normal to mid range focal lengths (typically 50-105mm) most macro lenses are regarded as dual purpose, being also useable for portraits (also see below).

Reproduction: high resolution photography of important or historic artwork, documents or artefacts, which is aimed at preserving the colour, texture, detail and aesthetic of the original piece

Very high resolution sensors: the more megapixels on a sensor, the more likely shortcomings of a lens will be exposed (not just sharpness). However, it should be noted that it isn’t that unusual for even a decent quality vintage lens to perform well on a high resolution sensor. Furthermore, whatever the camera, good technique is as important, if not more, than lens sharpness for obtaining sharp images.

Anything where heavy cropping is routinely relied upon: wildlife photographers will testify to this, although, as outlined above, good technique is usually more important than sharpness. 

I am largely indifferent to how tack sharp a lens is, and there are instances where sharpness can in fact create an unwanted added workload. For example, I shoot a lot of close-up/beauty portraits, and sharp lenses have a habit of showing skin flaws that even the naked eye can’t see. This means more retouching work, which can be very time-consuming (which is also an inherent drawback of dual-purposing macro lenses for portraits). It’s not like I can get around the problem by shooting the lens at “less sharp apertures” (wide open) either, because close-up portraits are generally taken on longer lenses of 85mm+ (in order to increase working distance and minimise facial feature distortion) which necessitates stopping the lens down to extend the depth of field.

Other Lens Traits to Consider

Dimensionality: this pertains to how a lens renders space and depth, and can be loosely described as how quickly and effortlessly (almost passively) the spatial placement and separation of objects in the frame can be perceived, i.e. without studying the image for any significant length of time – it just smacks you in the face instantly. Of course, good lighting helps massively with dimensionality, but specific lenses have inherent dimensional rendering. A famous example of such a lens is the Carl Zeiss Distagon 28mm f/2, which is often nicknamed “Hollywood Distagon”, alluding to its dimensional, cinematic rendering (thought to be due to its strong field curvature). You really don’t need an expensive Zeiss lens though, or even a prime lens; in fact, certain kit zooms are noted for their dimensionality.

Bokeh: from the Japanese word “boke” (to blur), bokeh is the aesthetic qualities of the out-of-focus areas of the image. This is an important facet of optics to consider because the artistic qualities of bokeh can vary quite markedly between lenses, and their appeal is highly subjective. Many of the “harsh” and “distracting” rendering characteristics of many older vintage lenses have been largely engineered out in modern optical designs; with manufacturers favouring smooth and dreamy (uncomplicated) bokeh. This has led to a growing community of enthusiasts purchasing and adapting vintage lenses to their mirrorless cameras, with the corollary that these “art lenses” each give unique and aesthetically interesting bokeh that modern lenses cannot provide.
Notably, whether using modern lenses or vintage lenses, bokeh is almost always at its most pleasing with the aperture wide open; when the iris is circular. As a lens is stopped down the iris generally assumes a polygonal shape corresponding to the number of aperture blades, which gradually curtails the most pleasing bokeh qualities and leaves polygonal specular highlights. Therefore, the more aperture blades a lens has (especially if they are rounded blades, rather than straight-edged) the more rounded the iris will remain as the lens is stopped down, effectively “protecting” the bokeh.

Microcontrast: this is rather an ambiguous term and has been given various definitions. Broadly speaking it alludes to a lens’ ability to render broad intertonal detail and to reproduce colours accurately. The most elegant and detailed definition I’ve found to date is: “the level of tonal separation, colour accuracy and acutance in the in-focus areas of the image” [1]. Microcontrast is somewhat linked to sharpness, however there are plenty examples of lenses that are sharp but have poor microcontrast. By contrast, there is no correlation between microcontrast and dimensionality [2].

A Very Brief Historical Perspective

If we study the performance of vintage  lenses (up to 50-60 years old) we can clearly see that many primes in the range of 35mm to around 200mm are capable of resolving huge levels of detail on even the most demanding, modern high resolution sensors. Personally, I have tested 5 different vintage 50mm lenses (most of them available for less than £50 eBay) on my Nikon Z6 and it is honestly shocking how sharp all of them are. Yes, modern prime lenses are generally a bit sharper (I’m not saying old lenses are equal to modern ones), but, again, can we spot this in side by side comparisons without the level of magnification at which we will never artistically appreciate our images anyway? In most cases, no; in fact, it would be far easier to tell them apart by other characteristics, such as bokeh. The only real blatant advances we’ve seen in sharpness are with zoom lenses (all types, in the last 20 years or so) and wider (from around 28mm) primes. What I will happily concede is that lenses have generally become much sharper at their (also, nowadays, faster) maximum apertures and with less artefacts, such as glow, chromatic aberrations and colour fringing. Therefore, if a difference of 50-60 years can only make a relatively small difference then what perceivable advantage will a modern lens realistically have over its nearest competitor? If we need stupid levels of magnification or an MTF chart to tell us which lens is sharper then what’s the point of basing a purchase decision on sharpness at all? Would it not be far better to compare other traits and the whether the overall rendering of a lens is pleasing to us?

Conclusions

Again, for clarity, I’m not dismissing sharpness completely. What I am saying is that these days sharpness is the lens equivalent of camera companies trying to sell us megapixels. It’s mostly all marketing. With good post-processing technique, boosting sharpness powerfully without introducing artefacts is quick and easy if we feel an image really needs it. Whereas, can you imagine trying to change the bokeh of an image in-post if it is unsightly and distracting (rhetorical question), or having to go through a repeated laborious process of trying to add “pop” to an otherwise flatly-rendered images? Criteria for a lens purchase should in most cases be based on overall rendering, because once you quickly get past sharpness you have to live with what’s left.

References

[1] https://www.youtube.com/watch?v=Cy0fq0FHXDM

[2] https://www.youtube.com/watch?v=TPu4N6CnkGg

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This article was written and conceived by the well established and highly regarded photographer David Ellinsworth. You can find his wonderful website at DavidEllinsworth.com, his Instagram here and Flickr account here.

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This has been Part 4 of a 12 part series for “12 Days Of Christmas 2025”. A collection of new articles and so much more from Mark G Adams from One Camera One Lens Photography as well as guest authors. Catch them all if you missed any here.