E-P1 17mm lens corrections
Filed in Olympus Pen - July 17, 2009
Top image converted in Raw Developer. Bottom image converted in Olympus Master. Both at default settings. (Please don’t try to judge image quality. This is a screen print using different preview software at different magnifications).
There are a number of subtle differences here, like the slightly too aggressive S curve that Olympus Master is adding. However, the overwhelming difference is the fact that Olympus Master has access to a lens correction routine.
I’ve emailed Brian at Iridient to see if the lens correction info is something that he can get access to. I’ll report any interesting response.
Several thoughts come to mind:
- this may be the sort of reason why Leica has announced that it won’t be developing (badging) a micro fourthirds camera. Correcting that sort of distortion is bound to have an impact on image quality (their announcement talked about there being too many compromises as far as I can recall).
- a quick brick wall test shows that Olympus is over-correcting the problem in the extreme corners. The files look *really* odd.
- given that Olympus and Panasonic are competitors as well as collaborators in the micro fourthirds project I wonder what prospect there is of successfully mixing and matching lenses and bodies from the two brands.
- whether this distortion is a problem or not will depend on what sort of photography that you are doing and how much processing you are prepared to put up with. I feel it is in the same camp as the Leica Magenta-is-the-new-black issue. It is a cost of doing business with the particular style of camera.
- the distortion problem won’t exist with lenses that are designed for rangefinders and then adapted to micro fourthirds. The Zeiss 21mm that I’m planning to use is widely regarded to be very well corrected in terms of distortion, and, don’t forget, that it covers a much bigger imaging area than the E-P1 will be using.
- Olympus Master not only corrects (over-corrects I’ve changed my opinion about the over-correction) the distortion, but it also makes the image area smaller. This is more or less a given as a part of the correction regime. If you are prone to composing near the edges of the frame, especially on a live view camera, then this is going to be something of a lottery.
Anybody have any good recommendations for correcting lens distortions? I’m not going to want to do it on every photograph and, anyway, Olympus Master isn’t going to be a regular part of my photographic life.
Hi Colin -
Is the correction applied in Live View (I assume it must be..) ? If so I assume you could compose that way….
Either way, I have to say I’m not terribly convinced that this camera is quite the Second Coming that the interfora make it out to be.
David
July 17, 2009 @ 9:06 pm
David – as far as I can see the live view display is corrected. I haven’t yet explored whether it is the same correction as gets applied during the raw conversion – that is, how wysiwyg is the display?
July 17, 2009 @ 9:19 pm
I don’t see over-correction but they have gone all the way to full rectilinear, which isn’t necessarily desirable. (Actual I think it’s a problem with a lot of modern WA, I like some barrel distortion.)
Panasonic don’t quite go so far with the LX3, I wonder what they do with the new G-series?
July 17, 2009 @ 10:05 pm
Martin –
over correction is evident in brick pattern type photographs. In the extreme corners the distortion reverses.See here. It wouldn’t show in many pictures. I think that the softness in the corners is a bigger problem. The picture above obviously has no corner detail to worry about.July 17, 2009 @ 10:15 pm
You have a few options for lens distortion. If you want to be a twiddly geek, you can use a program like Hugin. If you want to be patient and wait for them to support your camera, DxO is well regarded in lens calibration and correction in their raw converter.
July 17, 2009 @ 10:28 pm
Chris – I’d forgotten about DxO. Their development path and my camera habits haven’t overlapped much but maybe micro fourthirds might be the time…
For now I’m playing with the options in Photoshop. Not surprisingly maybe that’s got a lot more sophisticated in this area.
July 17, 2009 @ 10:34 pm
Would you mind posting a link to your corrected and un-corrected brick walls? DpReview did include one brick wall shot in its previews, but that is such a jumble of slanting planes as to be useless, and it is shot in jpeg, so probably corrected. It did look pretty sharp in the corners.
I wonder if barrel distortion is a normal characteristic of pancake lenses (in which case your 21 Biogon would not be troubled with this, as it is much more than 21mm long).
scott
July 17, 2009 @ 11:27 pm
I don’t know if PTLens comes in a Mac-friendly form but it is a PS plug-in. Easy to use and they also use a regularly updated camera/lens database.
July 18, 2009 @ 8:11 am
Scott – sorry I trashed it. At that point I wasn’t imagining writing a lot about the lens. Not normally my kind of thing.
July 18, 2009 @ 8:55 am
Actual I think it’s a problem with a lot of modern WA, I like some barrel distortion
Martin – I agree with you in general, but with a wide angle being used to create a more normal view the effect of the distortion can be unsettling.
July 18, 2009 @ 9:10 am
I wonder if barrel distortion is a normal characteristic of pancake lenses (in which case your 21 Biogon would not be troubled with this, as it is much more than 21mm long).
Scott – I used a Pentax 40mm pancake a lot in the distant past. I don’t think we can attribute distortion just to the pancakeness of a lens. However, deciding on a maximum lens size must have been a real constraint for the lens designers who couldn’t go on adding elements to correct for ‘faults’.
I seem to recall that in the ZM range there are two 21mm Biogons. The faster one distorts a bit, but the slower one doesn’t. It is the slower one (the ‘C’ f4.5) that I have.
July 18, 2009 @ 9:14 am
The Pentax 21 DA Limited pancake has quite pronounced barrel distortion. But that offers a distinctly wider field of view on APS-C than the old 40 SMCP-M does on full-frame 35, so I imagine the design challenge is greater.
July 18, 2009 @ 3:58 pm
Is it possible to turn off the correction in the Olympus software?
I really don’t want some mediocre distortion correction. First, it does not correct 100%, there is still some clearly visible barrel distortion present in your “corrected” example.
Second, most programs (including PS) use bicubic interpolation which softens the image. For quite good correction I recommend The GIMP. It can adjust to central and edge distortion separately and features the sinc256 Lanczos interpolator which yields results with astoundingly small (often effectively invisible) loss of quality.
Sinc interpolation uses a lot of CPU power and probably won’t appear in embedded devices any time soon. So I recommend to stay away from internal JPEGs from cameras such as this.
July 25, 2009 @ 9:47 am
Nj – I’ve not found a way of turning off the corrections in Olympus Master. I haven’t looked in Olympus Studio.
First, it does not correct 100%, there is still some clearly visible barrel distortion present in your “corrected” example.
Be aware of my comments about the camera not being completely level. A slightly tilted camera plays havoc with distortion.
July 25, 2009 @ 9:58 am