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11-01-2017, 10:06 AM   #1
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Do Lens Distortions still Matter?

I grew up taking pictures in the age before digital, where it was difficult, if not impossible, to correct problems with images after you clicked the shutter.

You were to a large degree at the mercy of the lens and film when it came to tint, pincushion, etc.

Now with post processing, correcting problems like barrel distortions are fairly easy. Even sharpness can be corrected to a certain degree.

Yet reading reviews of lenses, a lens which is better when it comes to factors which are hard to correct (like lens flare and sharpness) will often be ranked lower than another lens which is worse in these areas but produces a more 'pleasing' photograph.

The most basic example are statements such as "this lens produces too clinically sharp an image for portraits"

Yet it is easy to soften an image in post, as it basically entails reducing the 'accuracy' of the image by adding blurr. On the other hand, in order to sharpen an image what is needed is to try to add back information which was lost by the lens.

11-01-2017, 10:16 AM   #2
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Yes, lens distortions matter, but to a lesser extent due to software correction. Warping away barrel distortion can reduce sharpness in the distorted areas.

Coma distortion, invisible for most daylight photos, can be highly visible in night sky images. Coma is difficult to correct with software. Some lenses that work great in daylight work poorly at night.

I've never encountered a lens that was too sharp. I don't shoot portraits. I can understand why a portrait photographer might not want to have to apply software blur to every portrait.
11-01-2017, 10:17 AM   #3
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I think they only matter if they matter to you. Flare, for example can be hard to correct and might ruin a shot. On the other hand you can use it in your image as a creative tool.
Sharpness can be hard to add. I would say impossible but I know there is software that claims to be able to do this. If my image lacks sharpness where it is needed, I typically just reshoot.
As far as I'm concerned a lens can't be too sharp for the eyes. If the rest of the face looks too sharp I'll soften it a little but that is not a common scenario.
11-01-2017, 10:23 AM   #4
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It's an interesting point.

I own the Sigma 17-50 f/2.8 which - for an inexpensive and fast zoom lens - is remarkably sharp at all focal lengths and apertures (even wide open), with easy-to-correct distortion and vignetting. The worst of its minor foibles is purple fringing at wider angles, especially in the corners - but this is easily remedied. It's a great walk-around lens when you don't want to be switching primes every 15 minutes. That said, the rendering has little character, IMHO. To coin the term used in your example, it's rather "clinical".

I have other zoom and prime lenses that aren't edge-to-edge sharp like the Sigma, and may be considered quite poor performers in several other ways optically, yet the overall way they render lends great appeal... perhaps not for every photographic occasion, but in certain situations.

When all's said and done, a lot of lens reviews are - for the most part - subjective, and based on the individual photographer's preferences

11-01-2017, 10:38 AM - 1 Like   #5
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Yes they matter. Meyer Optik Görlitz, Lensbaby and now Leica are making a lot of money from distorted glass.
11-01-2017, 10:40 AM   #6
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Reading reviews the complaint which I question most are those regarding the hue of the image.

In the past, using a red filter when taking the shot for underwater shots was the norm. But now hue distortions are typically addressed in post.

Advantage (and this applies to sharpness as well) is that you are not limited to a single solution, you are able in post to adjust the level of correction which is most pleasing to the eye.

---------- Post added 11-01-17 at 10:46 AM ----------

QuoteOriginally posted by D1N0 Quote
Yes they matter. Meyer Optik Görlitz, Lensbaby and now Leica are making a lot of money from distorted glass.
Good Point... it is a trend which I don't understand beyond photography competitions which 'forbid' post processing of images.
11-01-2017, 10:49 AM   #7
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QuoteOriginally posted by Steve Grosvenor Quote
Reading reviews the complaint which I question most are those regarding the hue of the image.

In the past, using a red filter when taking the shot for underwater shots was the norm. But now hue distortions are typically addressed in post.

Advantage (and this applies to sharpness as well) is that you are not limited to a single solution, you are able in post to adjust the level of correction which is most pleasing to the eye.
Ah, I thought you were referring to geometric distortion, not colour reproduction.

Certainly, colour reproduction can be easily dealt with in post. In fact, the colour reproduction from our cameras is rarely accurate regardless of lens used, unless you create a colour management profile for the camera and lens combination, so some degree of colour tweaking is usually necessary to get an accurate reproduction. Beyond that, most of us would want to make further adjustments according to personal preference.

That said... The way some lenses render colour and contrast (without requiring much in the way of adjustment) can make them particularly attractive, especially for those who prefer to get the image right "in camera", without having to rely on post-processing.

11-01-2017, 10:54 AM   #8
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QuoteOriginally posted by Steve Grosvenor Quote
the complaint which I question most are those regarding the hue of the image.
Much like complaints about sharpness, distorted colour hue is only objective to a point, basically to separate poor lenses from the rest. Perceived differences in hue (and likewise sharpness) between good and great lenses are affected more by degrees of deficiency in colour perception between individuals and their personal reactions to the composition, colours and contrast in the image than by measurable differences in lens performance.
11-01-2017, 11:29 AM   #9
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QuoteOriginally posted by Steve Grosvenor Quote

Good Point... it is a trend which I don't understand beyond photography competitions which 'forbid' post processing of images.
It's about the image. Everything is post-processed. JPG conversion is post-processing. Adjusting the light intensity through a negative is post-processing.
I don't understand it either. Highly manipulated HDR images straight from the camera are somehow OK, but adjusting the exposure and saturation aren't? I suppose if you want all your subjects to look like they're in a sauna because the sensor is very sensitive to red...but I'll keep knocking that saturation down a little in the red channel or just desaturating images a bit overall.

If a lens distortion makes the image one you're less pleased with, then adjust. Most of the time it's essentially impossible to tell, unless you're doing a tight portrait or scientific macro.
11-01-2017, 11:31 AM - 1 Like   #10
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At the end of the day I think all the things that software processing can fix (which is a lot) are counteracted by the fact that we are now able to pixel-peep. Thus, users are more critical of lenses than before, which is why we're seeing a push toward new ultra high-performance optical designs (consider the D FA* 50mm versus older 50's).

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11-01-2017, 12:46 PM   #11
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Well, as others have stated, photography is ultimately about the image.

And even from a perceived-IQ standpoint, freedom from distortion may rank significantly lower for me than attributes like microcontrast, colour rendering, flare resistance, control of vignetting and chromatic aberrations.

That said, however, I do value when a lens design controls geometrical distortions to a residual degree that doesn't interfere with my composition. I really enjoy the precision-framing that is possible with a (near-)100% viewfinder, and don't want to find in post that I have to give up on a detail, shape, or line that I wanted in my composition, just to get rid of that distortion. (Not to mention the loss of potentially valuable pixels.) Actually, I've come to switch off the lens-based distortion corrections in my raw converter and apply them only where I find them necessary on an image-to-image basis. I've also found that, with wideangle shots, a bit of residual barrel distortion can even help to make spherical shapes in the image corners look less deformed (think: people's heads, street lamps, etc.). And I sure worry more about distortion when I'm shooting, say, architecture or am doing repro work than when I'm out on a landscape shoot. Did I mention that, depending on my photographic mood and intention, I am an absolute sucker for the deliberate wild distortions that fisheye lenses produce? (Even those can often be mitigated by careful composition, without resorting to corrections in post).

It should also be noted that more complex patterns of distortion, such as the notorious mustachio-shaped form (common in ultra-wideangle lenses), are hard to correct even in post and clearly not desirable.

Personal bottom line: distortion control still matters in the digital age, if somewhat less than it used to, while the requirements for it will differ considerably across photographic subjects or genres.

Last edited by Madaboutpix; 11-01-2017 at 01:14 PM.
11-01-2017, 01:39 PM   #12
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Yes, they matter...

We can "correct" in PP, but there is no such thing as a lossless or fully "natural" correction. An appropriate analogy might be cosmetic surgery.


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11-01-2017, 01:58 PM   #13
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QuoteOriginally posted by stevebrot Quote
Yes, they matter...

We can "correct" in PP, but there is no such thing as a lossless or fully "natural" correction. An appropriate analogy might be cosmetic surgery.


Steve
Cosmetic surgery can be botched. So can lens correction. I avoid the whole issue. I select the lens I want for the job based on how much I can control the need to correct.

I don't even mind the fisheye look as long as I can control the horizon line. If I can I'll likely use the DA 10-17. If I can't, I'll switch to the Sigma 8-16 which is corrected down to 12mm. It will be interesting to see how the new DA* 11-18 stacks up.
11-01-2017, 02:10 PM   #14
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QuoteOriginally posted by normhead Quote
Cosmetic surgery can be botched. So can lens correction. I avoid the whole issue. I select the lens I want for the job based on how much I can control the need to correct.
I'm much the same. I rarely add profiled lens corrections in my post-processing these days... For barrel and pin-cushion distortion, I'll manually correct if the shot needs it. If I need really straight lines, I'll choose a more-or-less rectilinear lens. As far as vignetting is concerned, I generally like natural vignetting and - depending on the shot - will often add a little more
11-01-2017, 02:21 PM   #15
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If we count vignetting as a distortion then I'd say that's one distortion that rarely matters on digital. Sometimes vignetting adds to an image. In the cases where it subtracts from an image, 30 seconds with software can fix it. Vignetting correction does increase noise, so a low-light high-ISO image with details in a vignetted corner is a special case that can't be easily fixed.
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