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-   -   Fish-eye and De-fish (http://e-group.uk.net/forum/showthread.php?t=49035)

MikeOxon 20th October 2018 02:51 PM

Fish-eye and De-fish
I have a Meike 6.5mm fish-eye lens in MFT mount, which I use on my Olympus E-M1 Mk.ii. This lens has received very good reviews and at around 125 for a fast - f/2 aperture - ultra-wide lens, I believe it represents excellent value-for-money.

It has been criticised because, since it was originally designed for APS cameras, the top and bottom of the circular image are slightly clipped by the MFT frame. In practice, I have not found this to be a problem, since these areas tend to contain sky and feet, which can be 'dubbed' in with an editor.

Recently, I have been visiting several National Trust houses, which now allow photography, providing flash is not used. This presents a challenge, since light-levels are often low and it can be difficult to capture the overall look of small interior rooms. The Meike excels in both light-capturing ability, with good image quality, even at full aperture, and field of view.

I also use the 'PanoTools' 'remap' plug-in for Photoshop, which can do a good job of converting the circular image to a conventional rectilinear image, with what I consider to be remarkably good results. (PanoTools is a free suite of programs and libraries originally written by the German physics and mathematics professor Helmut Dersch.)

The following images show the results of 'de-fishing' one of my photos from Wadesdon Manor, using the PanoTools plug-in:


For comparison with a more conventional lens, the image below marks the area covered by my Olympus 9-18mm zoom, when used from the same location. as the Meike (de-fished).


Finally, an image that can only be made with a super-wide lens - this is the 'de-fished' view from the Meike, looking vertically upwards from inside the Dairy Court at Chastleton House:


Otto 20th October 2018 03:23 PM

Re: Fish-eye and De-fish
The "de-fishing" seems to work very well, although there is still a bit of distortion. Inevitable I suppose. I use my 9-18 a lot in such places and am generally pleased with the results. DxO does a good job of removing the minor distortions and aberrations. I'm quite surprised at how much extra the fisheye can see. I have the 16mm OM full-frame fisheye but I doubt the f-o-v on mFT would be much wider than the 9-18. I suppose I should try it and see!

MikeOxon 20th October 2018 03:33 PM

Re: Fish-eye and De-fish

Originally Posted by Otto (Post 460507)
......... I'm quite surprised at how much extra the fisheye can see. ..............

So was I, when I first saw the de-fish results :).

The settings for FOV in the PanoTools menu are quite critical for controlling the curvature at the edges. Since I first posted, I've made a further small adjustment to the second image, which has helped a little.

My fish-eye shots were all taken at f/2. Possible a smaller aperture would improve edge definition but my objective was to test the low-light capability

drmarkf 21st October 2018 12:58 PM

Re: Fish-eye and De-fish
That's really good, especially considering the cost of admission.

I'm looking forward to seeing what the new range of Laowa ultrawide and FE lenses for MFT can do. Their 7.5mm has extremely low rectilinear distortion, and stopped down a bit gives superb results. These are likely to be significantly more expensive than your lens, but still considerably cheaper than anything Oly/Panny are ever likely to produce.

OM USer 21st October 2018 02:05 PM

Re: Fish-eye and De-fish
Small enough to fit in my bag and certainly a good price. Your de-fished reults look very promising.

MikeOxon 22nd October 2018 10:15 AM

Re: Fish-eye and De-fish

Originally Posted by OM USer (Post 460613)
............ Your de-fished results look very promising.

I tried photographing a large wall from very close, to test the de-fish performance. The brickwork itself was not perfectly even but this is the result, before and after de-fish:


To test resolution of the Meike 6.5mm towards the edge of the frame, I took the following shot at f/8 (looking vertically upwards) and then compared with an actual-pixels area, near the edge:


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