rx100 the one to beat?

Started Feb 6, 2013 | Discussions thread
YiannisPP Senior Member • Posts: 1,621
Re: for the RAW shooters..

AdamT wrote:

I don`t have LR so haven`t a clue what it's doing . I use the Fisheye correction option with the RX100 files on the same setting which works for the canon SX50 (the S90 needs less and the G1X less again) .

Thanks for pointing me to such things Adam, I've learnt a few new things. I downloaded the trial of PT-lens and I now realise that you actually meant de-fish, as opposed to correct barrel distortion:) Though I'm still not sure what is the difference in essence, if there is one. Do you know? I read somewhere that they're not the same, but it didn't elaborate.

The generic de-fishing option works well for the RX-100 I've found and it leaves the image uncropped for you and you can take advantage of the wider part that is thrown away by the camera. The barrel-pincushion distortion correction option, although it uses an RX-100 specific profile, doesn't quite match the OOC jpegs, plus I couldn't make it leave the black bits, it crops automatically. Or did I miss something?

In any case, I've now corrected 3-4 images with the de-fish trick and I matched the OOC jpegs pretty accurately overall, with only the corners still being a little bit more stretched out in the OOC jpeg. I'm still not sure which is the correct one, I need to shoot something with a straight line near the top for example, in order to see if my correction doesn't correct the corners 100%, or if the lens itself has some more complex distortion, with some pincushion in it which the jpeg engine doesn't correct. If that makes sense.

So..here's the thing I've found, the RX100's effective MPs in WA are actually 17. Around 3MPs are thrown away due to the lens' severe distortion which has to be corrected. That is after the camera crops both top and bottom (after the defishing) and left and right in order to output a 3/2 aspect ratio image. Can't be 100% sure it's 3 and not 2.5 because I am not matching the in-camera correction exactly, but it's very close.

If you keep the sides (by doing what you suggested), you have a 1.63 aspect ratio, 18.5MP, 25mm wide equivalent image. It's actually just a tad wider than my Pana TZ7 which is 25mm equivalent.

So overall a useful thing to know to get that something extra from the camera.

By the way I'm curious, what % of de-fishing do you have to use to match the OOC jpegs for the SX50, the S100 and the G1X? The RX100's OOC jegs are matched with 70%.

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