Olympus 12-40 distortion on the Pocket 4k

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brianmolloy

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Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 5:43 pm

Hello everyone! I recently bought the Olympus 12-40 f2.8 lens for my new Pocket 4k and am noticing a lot of barrel distortion at the wide ends. I recognize that the camera isn't doing any lens corrections but I expected much better results out of this 'pro' lens and based on the fact that it is on the camera for a lot of the promo shots. Fortunately, the distortion can be corrected in resolve but it adds another step to the post workflow. I also included a still showing some of the distortion at 12mm.

Is anyone else experiencing problems like this or has any alternative lens suggestions?

Thanks so much!

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rick.lang

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 7:04 pm

Brian, I hope I remember to post a still next month when using the unreleased Tokina CinemaATX 11-20mm T2.9 PL zoom on the undelivered BMPCC4K (assuming both items arrive in January). Will be interesting to post a comparison with both lenses uncorrected for distortion.


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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 7:07 pm

Yes its the nature of the lens. Remember it's a still lens with distortion to be corrected in software. You can read about it on multiple photography forums. I have a slrmagic 10mm which shows much less distortion than the Oly. I also have a tokina 11-16mm cinema lens in a m4/3 mount and it shows very slight barrel distortion and has the least compared to the Oly and slrmagic. The Olympus 12-40m I own has the most distortion.
Last edited by mico p on Fri Dec 21, 2018 7:35 pm, edited 2 times in total.
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John Paines

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 7:14 pm

The Zuiko 12-100 is slightly worse than the Panny 12-35mm, at 12mm. If the Tokina isn't a *lot* better, somebody should be unhappy. OTOH, barrel distortion isn't unheard of. The AMC mini-series, "The Little Drummer Girl", is full of it, and nobody would describe the production team as unskilled.
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Australian Image

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 7:21 pm

You have to note that 12mm is pretty wide (24mm in the old 35mm film days) and shooting vertical lines at a close distance will show this sort of distortion. Also, most modern still lenses are now designed so that distortion is corrected in-camera or through software, it helps making deign and manufacture easier and cheaper. My understanding is that all m4/3 zooms involve some software correction.
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Steven Kornreich

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 9:29 pm

So if shooting RAW doesn’t DaVinci Resolve have software correction built in for this lens?

Which MFT 12mm lens has the best optical correction?
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Australian Image

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 21, 2018 10:06 pm

Steven Kornreich wrote:So if shooting RAW doesn’t DaVinci Resolve have software correction built in for this lens?


If it's in their lens database, then it should.

Which MFT 12mm lens has the best optical correction?


As far as I'm aware, that may apply only to the prime lenses. The older 4/3 lenses were generally all optically corrected, notably the HG and SHG lenses.
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joe12south

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 28, 2018 5:28 pm

Completely average amount of distortion for a lens that wide. We are so used to lens correction either in camera or in RAW processing that we forget this.
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Robert Niessner

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Re: Olympus 12-40 distortion on the Pocket 4k

PostFri Dec 28, 2018 9:35 pm

The only wide MFT lenses with little distortion are from Laowa, Tokina and Veydra.
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Steve Holmlund

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Re: Olympus 12-40 distortion on the Pocket 4k

PostSat Dec 29, 2018 1:35 am

Resolve Studio has a straight-forward lens correction in the Edit tab. I didn't see any presets for this lens. If you have Resolve Free, add a Lens Distortion node to the clip in the Fusion tab (Tools > Warp > Lens Distort) and then on the Lens Distortion Model sub-panel, adjust the Distortion and Quartic Distortion sliders.

I'm no expert so maybe someone else has better input on corrections in post. Also not sure about the trade-offs of using these software corrections.
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John Griffin

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Re: Olympus 12-40 distortion on the Pocket 4k

PostSat Dec 29, 2018 10:45 am

joe12south wrote:Completely average amount of distortion for a lens that wide. We are so used to lens correction either in camera or in RAW processing that we forget this.

Not at all. 12mm isn't that wide on M43 and equivalent lenses on DSLR's for APSC or full frame don't distort to this degree and have to be designed this way as they have optical VF's. M43 with it's EVF can liberate lens designers to produce compact lenses without having to worry about distortion if it is corrected in-camera or in post. The 12-40 is a superb lens which is sharp right to the corners even wide open and has a great MF action. Resolve has 2 tools for correcting this but on the BMPCC4k you need to be aware of this when framing. I have not noticed any image quality (loss of resolution) from using this tool. If you need 12mm without any distortion there is a Laowa 12mm 2.8 for full frame which could be adapted and this has almost zero distortion even on full frame which makes it 2x as wide as a 12mm design for M43. Filtering for ND will be a problem though as it has a big front element that needs a 95mm round filter or 100mm square filters (with adaptors).
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