Hi all,


I recently sold my DSLR equipment in favor of an OM-D E-M5, so I am new to this format and this forum.

I have a question about in camera lens correction as it is the case with Panasonic/Olympus Cameras and native lenses.
So far I understood that correction data is embedded in the RAW files and automatically interpreted by Lightroom/ACR when importing the files. So I am actually never going to see the non-corrected files, right?

However, if I use PTLens (as I always did with my DSLR-RAW's) there still seems to be a lot of distortion in the images and after using PTLens the images look much more pleasant.

This is especially the case at 12mm wide angle with the 12-50mm kit lens and quite noticeable with the 20mm 1.7 pancake.

What are your experiences with this? Is there something wrong with my camera or is in-camera correction just not that good as I hoped it would be..?

This really confuses me right now. And the fact that there are no profiles available for Panasonic/Olympus in Lightroom/ACR because of this feature makes it even worse..

Thanks for any help on this.

-Gino

Can you post a couple of examples?

I know DxO does its own profile corrections, not sure if they also use the 'built in' correction for the RAW files or not.

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EOS: 5DII, 30DIR, 24-105L, 35L, 135L, 15/2.8 FE, Σ 50/1.4, Σ 105/2.8 macro
Mu43: GF2, E-M5, P14/2.5, P20/1.7, O45/1.8, P7-14, O12-50, P12-35, P100-300
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I don't have any comment regarding this matter...but what is PTLens?
is it Photo Tele Lens?

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My Gear : EM-5, E-1, EPL-1, + Lumix 20, 14; Fujinon 55; OM 35, 135; mZD 45, 12-50, 14-42, 40-150R; ZD 35, 14-54 mkI, 40-150 mkI

It's software, for geometric lens correction if you're not the guessing type. A web search might provide more insight.

Back to OP. I have PTLens, but I just went by the correction that is included in the files, including in the RAW files if open them with the most popular programs.

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GX1 - OM-D E-M5 - Lumix G 7-14 | 12-35 | 20 | 35-100 - Samyang 7.5 - 500px

Okay, so here's a little comparison between ACR, PTLens and the free converter Rawker which uses DCRaw that does not interpret the lens correction data in the raw-file and thus represents the unaltered image the camera takes:

1) RAW --> JPEG using Rawker
http://up.picr.de/11336458xg.jpg

2) RAW --> JPEG using ACR
http://up.picr.de/11336219dx.jpg

3) RAW corrected with PTLens Photoshop PlugIn
http://up.picr.de/11336432om.jpg

Both the in-camera correction and ACR/Lightroom leave a small amount of barrel distortion uncorrected, similar to the distortion you would typically see with a non-software corrected, well optically corrected lens. By correcting all the distortion, some additional resolution is sacrificed, and I guess they feel that a bit of distortion is to be expected.

The difference between your ACR conversion and the PTLens version is marked, which makes me think that PTLens is overcorrecting. It would be helpful to see an example with more straight lines, for example a simple horizon, to see what is going on here.

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Amin
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Amin, it seems you were perfectly right assuming PTLens is overcorrecting.
These images prove this very well:

1) Rawker (crazy distortion..)
http://up.picr.de/11336918zh.jpg

2) ACR
http://up.picr.de/11337001ed.jpg

3) PTLens
http://up.picr.de/11337020sc.jpg

I guess the in-camera correction is not so bad after all and maybe the best compromise. Weird though that with "real life" images my perception was so different..

Anyway thanks for discussing this with me! Great forum!

There are actually a lot of profiles available for Lightroom/ACR if you use the Adobe Lens Profile Downloader. (For Olympus lenses put in Olympus Imaging.) I use one for the 9-18 sometimes.