More fun with RX100, the true wide angle specs!

Started Feb 11, 2013 | Discussions thread
YiannisPP
Senior MemberPosts: 1,621
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"Real" (WA) resolution of other cameras: G15, S110, LX7, XZ2, P7700
In reply to YiannisPP, Feb 11, 2013

I downloaded Faststone and wasted some more of my time trying to see what the other manufacturers do just to let you know:) I didn't look into how good a RAW converter Faststone is in general, I just used it to get the non-distortion-corrected images from other manufacturers' cameras. Then I corrected the distortion myself in PTLens, to the same degree that the respective jpeg engines do (or as close as I could get). Then I cropped what remained of the original sensor output (where needed) in order to match the actual frame of the OOC jpeg.

I suspected beforehand that the RX100 would be among the worst "offenders" (being so small and with a sensor at least double of the other cameras), but I wanted comparative numbers.

If you're wondering where I found RAW+jpeg files from all these cameras, I found them in photographyblog. In their reviews they shoot some test scene with RAW+jpeg and have both files available (I checked the EXIFs to be sure it was the same capture).

So here's what I found. Results are in order of increasing distortion and hence resolution loss compared to the nominal MP count. Only talking about full wide angle.

Nikon P7700. The one with the least lens distortion and which consequently throws away the least MPs. The RAW file and the jpeg were actually very close. The distortion is very low to start with and it's not completely corrected either in the OOC jpeg, so as a result almost nothing is thrown away from the original RAW frame! You can't really go wider using RAW and you get almost the full 12MP effective resolution.

Olympus XZ2. Here again I found low distortion and the RAW file and the jpeg being fairly similar, but not almost identical as was the case with the Nikon. In the end it seems like around 11.2 MPs are being used after the mild correction and cropping required to make the final OOC jpeg. Again there is little to be gained in terms of wide angle. So the XZ-2's effective resolution is around 11.1MPs.

Canon G15. This was the first one that qualified for "fish-eye" correction! But only just. After correcting the distortion there's still most of the original 12MP, but for some reason I didn't understand, it throws away the periphery of the frame and keeps around 10.3MP for the final frame. Maybe Canon are purists and want to output uniform resolution across the frame, or else I don't know! So the G15's effective resolution is around 10.3MPs.

Panasonic LX7. Going more into fish-eye territory. This lens has some weird distortion pattern going on which I had trouble removing with PTLens. Ends up using around 8.5MP for the final OOC jpeg frame, I think.

Canon S110. Now we're into real fish-eye territory, you should see the uncorrected RAW file, it's probably 21mm wide! Correcting the distortion to the OOC jpeg's levels and cropping for a 4/3 aspect ratio leaves around 10.9-11MP. But then again it seems to discard some of the peripheral pixels and ends up using around 9.3MP for the final OOC jpeg frame.

As I mentioned in my original post, the RX100 ends up using around 17MPs of the available 20MPs and it's equally fish-eyed as the S110:)

Please note that these effective resolution reductions stemming from the lens design compromises (which have to be addressed by in-camera manipulations), are only relevant when one uses those cameras at the FULL Wide Angle setting. At any other focal length the distortion is lower and the resolution loss lower too, or insignificant.

Finally, please do correct me if you think I'm missing something. I do not claim to be 100% sure of my numbers but I am fairly confident they're close and at least useful in a relative way. I am assuming that what Faststone gave me was indeed the original frames as the sensor saw them. If someone knows otherwise please tell.

P.S. I do know that resolution is not only about the number of MPs, as well as that it's not as important in the grand scheme of life!

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