How Much Distortion Is There In A Fujifilm 18-55mm f/2.8-4 Lens?

Across the lunch table informal portrait of my granddaughter Emilie (click to enlarge)
As we waited for lunch to be served at a local restaurant, I placed my X-T1 on the table in front of me.
Watching her, I made a number of pleasing images.
Fujifilm X-T1, 18-55mm lens @ 34.3mm; ISO 400; 1/50th sec. @ f/3.6; Program mode

How much manipulation do you think is going on with your Fujifilm 18-55mm f/2.8-4 lens without you knowing about it?  I can't address Fujifilm's other lenses as the 18-55mm is the only XF lens I currently own.  But here is what I found.

In editing my X-T1 images, for the ones that need clear and crisp detail as well as wanting no "mushy" and "watercolor" greens, I have been using Photo Ninja to convert the RAW image to a TIFF, then edit that file in Lightroom.  Generally, Photo Ninja does a pretty good job in converting the RAW files and generating much detail with green foliage looking normal.  Recently, when I was converting an image of some buildings, I noticed a huge amount of barrel distortion in the image.

At that moment, it hit me that there is no automatic distortion correction when using Photo Ninja as there evidently is in Lightroom.  We use Lightroom and the images look good, but behind the scenes, Fujifilm and Adobe are manipulating your images.  You have no idea how much and you have no way to turn it off, even if you wanted to.  I don't mind automatic distortion and vignetting correction, but I would like the option, when I deem it necessary and appropriate, to turn it off.  In the case of the Fujifilm/Adobe partnership, the correction cannot be turned off even if you wanted to.  At least to the best of my knowledge.

Why want to turn it off?  Several reasons.  First, distortion correction can "stretch" or "compress" pixels around the edges of an image and reduce image sharpness. Additionally, automatic distortion correction can cause the edges of your images to be cropped off. Your wide angle lens may end up not quite as wide and you may lose the edges of your carefully composed image.  Thirdly, there may be a reason I need to record a scene exactly as found, for technical or legal reasons.  There may be other reasons you would want the option of turning the automated correction featured turned off as well.

Since Photo Ninja allows the user to build distortion and vignetting corrections so they can be applied consistently, I thought I would do that for future use.  Here is how I did it. First, I brought out my copy stand and a black/white block target print to photograph that would make it easy to first judge, then correct the distortion.  The X-T1 was placed on the copy stand, level and plumb, to eliminate any distortion or skewing of the horizontals and verticals I could accidentally introduce. I needed the camera to be exactly parallel to the target.

After lining up the camera, I made images at the focal lengths marked on the lens (18mm, 23mm, 35mm, 55mm) wide open as well as stopped down to f/5.6.  I wanted to see if any distortion changed as the aperture changed.  Additionally, if I wanted to go further and develop vignetting corrections, I could use the same images.

In Photo Ninja, I could adjust the slider controls to correct much of the distortion, then save it for that particular lens.  I was unable to correct the distortion entirely but plan on going back to fine tune it.  But the process is pretty straightforward.

Here are the images I made.  The first in each pair is the image as seen in Photo Ninja with its native and uncorrected distortion which is created by the lens formula itself. The second is the image as how the exact same image appears in Lightroom with the Fujifilm/Adobe corrections automatically applied.  None of the images have any editing done to them with the exception of a) increasing contrast and b) cropping out tape that was used to hold the print flat to the copy stand base.  

These first two images were made at 18mm as marked on the lens barrel (27mm ~e).

Fujifilm 18-55mm f/2.8-4 lens @ 18mm converted from RAW with Photo Ninja, which does not apply distortion correction There is quite a bit of barrel distortion using this lens at it widest focal length.  (click to enlarge)

Fujifilm 18-55mm f/2.8-4 @ 18mm; RAW image directly out of Lightroom 5.7.1; no editing (click to enlarge)
Even corrected in Lightroom, there is a bit of visible barrel distortion.

These next two were made at 23mm marking on the lens barrel (34.5mm ~e).

Fujifilm 18-55mm f/2.8-4 lens @ 23mm converted from RAW with Photo Ninja, which does not apply distortion correction (click to enlarge)
There is less native barrel distortion at this focal length than at 18mm, but there seems to be a bit more
complex distortion characteristics (mustache?).

Fujifilm 18-55mm f/2.8-4 @ 23mm; RAW image directly out of Lightroom 5.7.1; no editing (click to enlarge)
Distortion is pretty well corrected at this focal length, but a tiny bit of barrel distortion is visible.

These next two images were made at 35mm as marked on the lens barrel (52.5mm ~e).

Fujifilm 18-55mm f/2.8-4 lens @ 35mm converted from RAW with Photo Ninja, which does not apply distortion correction (click to enlarge)
Pincushion distortion is now starting to be evident at the 35mm focal length.

Fujifilm 18-55mm f/2.8-4 @ 35mm; RAW image directly out of Lightroom 5.7.1; no editing (click to enlarge)

These final two images were made at 55mm as marked on the lens barrel (82.5mm ~e)

Fujifilm 18-55mm f/2.8-4 lens @ 55mm converted from RAW with Photo Ninja, which does not apply distortion correction. (click to enlarge)
Pincushion distortion is now significant at the 55mm focal length.

Fujifilm 18-55mm f/2.8-4 @ 55mm; RAW image directly out of Lightroom 5.7.1; no editing (click to enlarge)
Little, if any distortion is visible.

I really like this lens.  With the exception of 18mm, the native distortion is not that bad and could be corrected as necessary in Lightroom or Photoshop with ease.  I think Fujifilm did a good job designing this lens while keeping the cost of the lens to a minimum.  They could have designed a perfectly corrected lens with faster apertures, but it would no longer fit the category for cost of a kit lens.

This automatic correction, or if you want to call it image manipulation, technology and process is applied to many different cameras across the spectrum in today's digital photography world.  In fact, Olympus does the same thing.  I experienced it with my previous E-M5 and current E-M1.  

The bottom line for me is that I appreciate the time and effort the manufacturers spend creating sophisticated correction algorithms as it gives me a better image without having to spend my own time and money fixing distortion and vignetting myself.  I have not found a significant disadvantage to image sharpness.  However, If I could ask Fujifilm/Adobe and the other manufacturers for one thing, it would be the ability to turn it off if I desired.  As of now, if you want to turn it off, you have to find a raw converter that does not recognize the image file's metadata and automatically apply the corrections.

Don't really worry about any of this.  I just think it is helpful, as a serious photographer, to know what is going on in the background and knew some of you like this type of information.

Now just grab your gear and go out and make images!

Thanks for looking.  Enjoy!

Dennis Mook

Many of my images can be found at www.dennismook.com.  Please pay it a visit.  I add new images regularly.  Thank you.


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