Quote:I already wrote "(or angle of view, more precisely)".

 

Then, if the labeled 12mm FL for the wide end of the 12-40mm lens is the true FL at the wide end, then after the distortion correction the diagonal view angle of the image would be that of FL like 13mm?

Quote:The native distortion at 12mm is very large, about 8% according to the test. On the other hand, it seems that the labeled FL at the two ends of a zoom lens is often not quite accurate.

 

My Nikor 16-35mm also has a high distortion at 16mm, about 5% I guess. Each time after I correct the distortion afterwards I clearly see the change in angle of view which I don't like. So I only correct the distortion when it is necessary.

Quote:No, it will be 12mm. Like I said, uncorrected lenses or under corrected lenses give a wider view for the same focal length. So what you end up with a similar view as any other well corrected 12mm lens, after correction of the barrel distortion.

Same story. The 16-35mm you have is not well corrected at 16mm, and gives a wider view than a better corrected lens at 16mm. When you correct the barrel distortion, you end up with a similar width as with the well corrected lens.

Quote:Yes, we know that 12mm is 12mm in theory. However, we know the companies fudge (i.e. a 300mm lens may be 280 mm). So, did they design the lens as an 12mm lens, with the uncorrected view like an 10 or 11mm field of view, and after processing you get 12mm? Or did they fudge, and the unprocessed is 12mm, while processed is only 14mm? 

 

If one calculates back, one could determine the actual field of view, but did anybody do that?

 

As a matter of fact, what about normal dSLR lenses, say a normal 18-55 kit lens that has barrel distortion that doesn't get automatically corrected. Is the field of view at 18mm the uncorrected or corrected one? Presumably the uncorrected one.

Quote:Yes, that is what I think too. I don't believe I get a 15mm view at the 16mm of the 16-35mm lens without distortion correction in post processing. Otherwise I will be very happy with the high distortion.

Quote:I think what matters is the final output regardless of the correction that happens before the RAW file is written on the SD card.

We always hear that such corrections affect the MFT results.

However, let's consider the review of the Olympus 12-40 which is heavily corrected for barrel distortion at 12mm. According to the whooping > 8% distortion at 12mm, one would assume it doesn't perform well at such focal length, especially in the corners. When looking at the resolution figures it doesn't appear to be the case at all. How do you explain this? Perhaps the figures would be even higher without correction?

Personally, I couldn't care less whether a lens is optically corrected or whether it's done in post processing. What counts is the en result: the resolution the whole system achieves. On the plus side, post capture corrections allows designers to create smaller lenses which is a good thing IMO.