Resolution of M43 lenses

Started Mar 31, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Dropoff seems like a greater problem to me...

Dr_Jon wrote:

The Photozone vignetting results are shown as "with correction" so I took my opinion from there.

The Photozone results are with the vignetting correction you get as a by-product of distortion correction. When the distortion is corrected, the original corners are effectively cropped and vignetting thereby reduced. So their "with correction" label doesn't refer to the additional correction you can get by means of the "shading compensation" option.

For the distortion I looked at a pic of my living room at 12mm - in the JPEG a picture on the wall is very distorted, in the DXO version it's rectangular.

Not sure what you are referring to here. If it is barrel distortion you are talking about, it should certainly be corrected in the OOC jpegs. Don't know how DxO handles the instructions on distortion correction embedded in the RAWs. Commercial RAW converters would normally honor them but others might not.

But perhaps you are talking about something else. If the picture on the wall is located toward one corner/edge of the frame, it may look more "stretched" once the barrel distortion is corrected. If so, this is simply an effect of moving closer to the rectilinear projection any non-fisheye lens is designed to deliver, not an effect of software correction per se. A WA lens that is perfectly corrected for geometric distortion (barrel, pincushion) by purely optical means would show the same distortion (i.e., "stretching").

Although on vignetting DXO produce a much wider FoV from the same shot, going much further into the corners and get vignetting to black with a 3mm filter attached, which is as thin as they get. The JPEG just chops this data off - so I wonder which is actually 12mm, hmmm, interesting, they can't both be. Opinions welcome!

See here:

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