Classic Olympus 90mm f/2.0 macro as tube lens

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Lou Jost
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Classic Olympus 90mm f/2.0 macro as tube lens

Post by Lou Jost »

I haven't seen anyone using the lens mentioned in my title as a tube lens, so I will put up a post about it. It is really beautiful!!! The example I include here is with a 7.5x Mitutoyo, on an MFT camera. The 90mm tube lens adds no chromatic aberrations, in spite of being a fast lens.

Here is a single frame of some densely intertwined out-of-focus white butterfly scales on the edge of a wing. This is the hardest subject to shoot when there is any kind of chromatic aberration; the false colors tint the white scales or form a haze around them after stacking. Yet here there is almost no trace of false color; it looks nearly as clean as the out-of-focus wing edge scales seen through my Printing Nikkor.

Image

Stacked photos (I show Zerene DMap results here) show no light falloff or degradation near the corners, except perhaps for the extreme last few pixels. The faint ridges on the butterfly scales are mostly resolved. I think the colors are exceptionally rich and I am pleased. This is a hard-to-find lens with a cult following, though not for stacking. It has less contrast than a modern digital lens, but maybe that's nice for some subjects.

Image straight from Zerene, no processing or exposure correction. Note that the purple and blue colors on the silvery wing itself, in the parts where scales have rubbed off, are not chromatic aberrations but thin-film interference between the layers of the wing, plus maybe some back-scattering of the blue color of the scales on the other side of this Morpho wing:
Image

Whole image with color and contrast adjusted, and 34% sharpening added...Edit: Maybe too much color!! That looks gross. I still don't understand the color management here, as it looked great in Photoshop:
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Center at 100%:
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Corner at 100%:
Image

Beatsy
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Post by Beatsy »

Impressive results Lou - especially the corners and lack of CA. Very "natural looking" rendering too (first pic shows it really well).

Lou Jost
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Post by Lou Jost »

Thanks! Here is the 90 with the 2.5x QV Mitu. Here the corners look a bit soft. No CA though. Image

rjlittlefield
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Re: Classic Olympus 90mm f/2.0 macro as tube lens

Post by rjlittlefield »

Lou Jost wrote:I still don't understand the color management here, as it looked great in Photoshop
There is no color management here. The forum software serves back exactly what was uploaded, possibly resized smaller if the upload was larger than 1024x1024 pixels.

The typical problem with color management is when somebody uploads an image that is not sRGB and the viewer's browser does not interpret the color profile the same way that the uploader's imaging software did.

Difficulties can also occur with monitor profile, particularly when some sophisticated tool like Photoshop honors the monitor profile, and a less sophisticated tool like a browser does not.

The simplest solution to most problems is to be sure that you're always uploading sRGB.

Most of this is discussed at FAQ: Colour Profiles and You.

--Rik

Lou Jost
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Post by Lou Jost »

Thanks Rik. I never use sRGB, that could be the problem, or part of it. I better read the link you mentioned.

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