Through a different lens: why we’re changing the way we process lens images

Digital lens corrections, once seen as a way to keep lens size and cost down, are now an inherent part of the design of pro-grade optics, such as Nikon’s Z 24-70mm F2.8 S

Technology moves forward, sometimes in incremental steps, other times in leaps and bounds. What’s not always easy to recognize is the point at which everything has changed so much that your existing way of working no longer makes sense or, at least, is no longer optimal.

That’s the point we feel we’ve reached with our approach to processing images when we’re assessing lenses. And, having recognized that technology has overtaken us, we’re updating our processing philosophy.

Simple explanation

In simple terms, we’ll now be applying all manufacturer lens corrections when we process images in lens sample galleries, since we believe that’s how most people will experience the results of modern lenses, most often.

Explanations of existing philosophy and approach

To explain why we’ve made this change, it’s helpful to look at what we’ve been doing up until now, and why.

When we first started reviewing lenses, mirrorless cameras didn’t yet exist, so we developed a processing philosophy based on showing lenses in their totally uncorrected form. DSLR lenses had to produce images that were consistent with what you could see through the viewfinder, so all corrections were strictly optional. Also, many of these lenses could be used on older cameras (including film cameras) that could not apply these corrections, so they wouldn’t necessarily be part of every users’ experience of the lens.

The arrival of mirrorless cameras, where the preview image could be corrected digitally, opening up new possibilities of lens design, in which glass could be used to correct some aberrations and mathematics could correct others. This allowed less complex lens designs, since it relieved some of the tensions and trade-offs of trying to correct every aberration.

Distortion profile applied No correction applied

The uncorrected version of this image (tap or mouse-over the right-hand button) looks disconcertingly distorted, but we’ve always felt it’s impact on the image quality of the corrections version that matters, not how ‘dramatic’ the uncorrected version looks.
Sony 24mm F2.8 G | F5.6

We extended our minimalist approach to these lenses, applying only distortion corrections that were a fundamental part of the lens’ design, on the basis it didn’t make sense to show images with some of the lens elements removed (whether those elements are glass or software).

We assessed whether corrections were considered essential based on whether the camera let you turn them off (most brands grey-out the option for lenses where correction is necessary).

However, for a number of reasons, this ‘warts and all’ approach no longer makes sense.

Explanation of what’s changed

The biggest change is that DSLRs and their lenses now represent a shrinking minority of lenses, with a vast majority of lenses being designed for mirrorless cameras. Moreover, these lenses are all being developed as parts of relatively young systems, in which virtually every camera is able to apply correction profiles for distortion, lateral chromatic aberrations and vignetting.

The majority of modern cameras will apply these corrections by default, and it’s only users that go out of their way to turn them off that might ever see the results without these corrections applied. Furthermore, it is not always possible to assess whether third-party lenses’ corrections are considered necessary, and some Raw processing software has taken to automatically applying some corrections for some brands, making it difficult for us to be consistent.

Distortion + Lateral CA correction profiles applied No correction applied
Similarly, if most modern cameras default to correcting lateral chromatic aberration, does it still make sense to show the image on the right? [100% crop from the lower left of this image]
Nikon Nikkor Z 24-70mm F2.8 S @ 24mm | F5.6

The final factor is that we now publish lens sample galleries before we’ve been able to review new lenses, and those images can be viewed independently of any review text, meaning there’s no opportunity for us to explain the rationale behind the way they’ve been processed, which risks causing confusion.

To make everything simpler, and more relevant for our readers, we will now apply any correction profile available for each lens.

Conclusion

Our lens reviews will still look at the results with minimal correction applied, to help understand the source of any imperfections in the results, but the sample images we show will much more closely resemble those that you’ll get if you mounted the lens on one of the bodies of its native system.

There will still be some edge-cases that create a little inconsistency: Canon doesn’t pass its distortion corrections on to third-party software, so we can’t show its corrections and may have to rely on Adobe or Capture One creating their own distortion profiles. We’ll be adding this shortcoming as a ‘Con’ to all our reviews of Canon R-series cameras, as a result, as it’s a hurdle all users will face if they wish to use third-party Raw processing software.

Overall, though, we’re hoping that our new processing approach provides images that are more consistent with the way the latest cameras work, and that look more like the ones you’ll get when you go out shooting.