Olympus 12~40 f2.8 PRO
(and it's cure!)
Images & text
Copyright by David Young
distortion in the 12~40/2.8 PRO Zoom: (Tested
on the E-M1 with firmware v 1.1.)
misunderstand me. I own and love the 12~40/2.8 PRO Zoom.
But there are problems with it and it seems that
are not willing to mention them; for fear that they will be cut off
future test units. This is an unfortunate reality for most
Fortuantely, for me, I have no connection to Olympus, other than as a
satisfied user of many years standing. Thus, I have no such
worries! They don't send me loaners for review, anyway!
has been a trend, in recent years, particularly with
micro-FourThirds lenses, to build the lenses leaving a lot of the
distortions uncorrected. Panasonic started this and Olympus
picked it up. Personally, I think it's a bad habit.
does, however, allow their designers to build smaller, lighter
excellent performance, at a more reasonable cost.
The argument goes that if you're shooting jpegs, the camera
will correct the distortion during conversion, and you'll never
And if the picture is perfect when it comes out of the
camera, what more can you want?
Correspondingly, if you shoot raw and develop your images using Olympus
Viewer 3, or
one of the commercial packages
which have the distortion profiles built-in (and which will automatically
correct it during developement) then you'll still
never see it. So far,so good.
But, what if - like me - you are addicted to one of the more obscure,
but very effective, commercial raw developers - such
as Silkypix - or
one of the open-source ones - like RawTherapee? Neither of which offer
automatic distortion correction. Now, you have
For the Olymlpus 12~40/2.8 PRO Zoom suffers from some rather serious, "moustache"
Now, I've been shooting since the mid-1960's, and I'd never heard of
this form of distortion, until recently! So, if you
haven't either, don't feel
bad. But it is real and it does exist in the 12~40/2.8 PRO Zoom.
before I tell
you the rest of the story, I'd like to point out that I have no
connection with Mr. Niemann, nor PTLens, other than a satisfied
lenses, by their very nature, nearly all suffer from some Barrel
distortion at the widen end, and a
bit of pincushion distortion at the long end. How well it is
controlled, is really determined by how much you pay!
Look at the image to the right ... at the wide end, the 12~40mm 2.8/PRO
has noticeable barrel distortion in the center of the image, but at the
edges, the distortion reverses, and becomes pincushion distortion!
Rather a bit like a handlebar moustache! Hence the
moustache distortion - though I gather the "correct" term is "complex
of this can be mathmatically corrected, if you know how ... which I
I contacted Tom Niemann, of PTLens fame.
the years, PTLens
has developed into an excellent, low cost, very fast and
easy-to-use program to correct
distortion in all manner of lenses.
The lens database includes some 2400 separate calibrations — far more
other application of it's type.
(BTW: the $25 license fee is good for as many computers as you own and
is a one time fee, covering ALL future updates & versions.
website is an excellent explanation of Pincushion, Barrel and
Complex (or Moustache) distortion - with comparisons (Click
to other, similar, software. He also has a 10 image free
trial, so you
can see if you like it, before you buy it.
As suggested by the PTLens website, I took a series of photographs at
intervals, sent them to Tom and he created the correction table
for the lens. (Note
that you need not do this ... it needs only to be done once for each
lens, and the correction table for the 12~40./2.8 PRO has now
created and is now included with PTLens.)
As you can easily see, from the corrected version of the above image
(at right), his program works very well.
Better yet, PTLens is a simple batch processor. It reads the
data of each image, disovers the lens & focal length, and then
the correction in fractions of a second. So, you can go
40 or more images, in mere seconds.
So, now my workflow is as follows:
1) develop with RawTherapee or Silkypix.
2) Run developed jpegs through PTLens, correcting distortion. (Very Fast!)
3) Resize & use.
In this way, I can process 500 to 600 images, for a
client, as fast as I can crop & develop them!
My preferred RAW developer is RawTherapee, as it is very good, fast, has a comprehensive array of features and it's FREE! RawTherapee supports
most raw formats, including some unusual ones like those from cameras
using Foveon and X-Trans sensors. The latest version (5) has a host of
new features, but the important one to this discussion is found in the
"Transform" menu. There you will find a "Distortion Correction"
slider. Just above that is a box labeled "Automatic". If
you click on it, the software will examine the embedded Jpeg (there is one in virtually every RAW file)
and make your image match it. This is possible, because the
embedded Jpeg, in virtually every case, has already had it's distortion
corrected by the camera. If, after that, it's still not quite
perfect, you can tweak things with the slider, but in my experience,
that is rarely necessary.
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updated: 12 November, 2017