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next PZ lens test report: Olympus M.Zuiko 14-150mm f/4-5.6 ED
[quote name='Rainer' timestamp='1310210548' post='9857']

Thanks for the report ...

albeit u4/3 will likely not become my favourite system.

However, reading the report, there is something I'm wondering about:

If distortion is corrected in-camera or by most raw-converters ... why

do they do an "incomplete" correction ... leaving some amount of

barrel (or pincushion) distortion in the image. I know that distortion

at a given focal length is also depending on focusdistance ... nevertheless,

I think they could do better than they actually do. What is the gain in not

correcting any better?

Just a thought ... Rainer


Of course, the real idea(s) behind that can only come from the software teams who decide on the level of correction.

A few thoughts and interesting points on the subject though...

Is it the lens, or the camera, which contains the correction parameters for the lens in question? If it is the camera, the camera's firmware needs to be updated and expanded with every new lens release.

If it is the lens, which plays part in this, for the Panasonic cameras the situation gets a bit more complex, as there are 2 sensor sizes... the GH series has bigger sensors that allow 16:9, 4:3 and 3:2 formats, which all would need a different amount of correctiing.

On the correcting itself, lenses do not always have a smooth or uniform distortion. Look at this lens, for instance. The corrected result actually looks to have perfectly corrected corners, while there still is a bulge from the distortion further on. This means that correcting it more will need much more complex algorithms.

Also, the more you correct, the more resolution you lose. Both recorded resolution because pixels get spread/stretched over more than one corrected pixels, but also edges get cropped.

All in all, it is hard to get to a totally ideal situation.

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next PZ lens test report: Olympus M.Zuiko 14-150mm f/4-5.6 ED - by Brightcolours - 07-09-2011, 11:51 AM

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