Fuji GFX 50SZ: Adapting Fine Vintage Lenses!

[Asher Kelman]

Originally Posted by Jerome Marot

Not quite the same, but this is a picture taken with the Minolta 100mm Soft Focus lens, to show the effect of increased spherical aberration:

On that particular lens, there is a slider to increase or decrease spherical aberration, to give a "soft focus" effect.

Jerome,

I am so pleased to see this. This look is new to me. It seems as if they are moving! I do like that they are not clinically sharp. Although supersharp images of flowers showing veins on the petals and the pollen grains on the antlers and stamens, or the fur coat of bees are technical achievements and indeed awesome, it is “cold hard fact” amazing but not “romantic mysterious” amazing! The latter is what soft focus does for portraits and flowers. I imagine it would work with flying doves too, but not perhaps a peacock or a giraffe as they are far to odd and particular to be romantic!

Asher

[Jerome Marot]

If you like this kind of effect, you can:
-emulate it in photoshop, by duplicating the image layer, add some gaussian blur and combine the two layers
-emulate it by using the free google nik software (glamour glow is a filter which does something similar, designed for portraits)
-get the Cokin dreams filter (exists in 3 strengths)
-get from ebay the Minolta Portrayer filter set or Zeiss softar
-spray some glycerin, smear some white petrolatum jelly or use a piece of woman's tight in front of your portrait lens
-try one of the lensbaby lenses
-and probably a few others I forgot about.

All these will give more or less the same effect (to a point) and are usually great fun to try. Nik software and the Minolta portrayer filter will attempts to keep everything sharp but skin tones. One of the lensbaby lenses is a manual shift lens, so it will allow you to more the zone of sharpness to your liking.

[Doug Kerr]

Hi, Asher,

Originally Posted by Asher Kelman

Great! Our lines of thought meet and you believe that I may have trouble finding the glow in the center with a single frame on the GFX sensor.

Well, spherical aberration is not a phenomenon that emerges as we move to a substantial distance from the center of the frame. It is there (essentially in full flower) at the very center of the image.

I'm not sure how it theoretically varies with distance from the center of the frame, or how it varies with distance from the center of the frame with a certain real lens.

In any case, I would not automatically assume that we would see less "glow" overall on a smaller frame image that a larger one.

With the larger frame size, do we see the glow to a fairly uniform extent across the image? If there is substantial glow at the center of the large frame image, it would surely be present over the scope of a smaller frame image, which is in effect just cropped from the center of the larger image.

But in saying that I have not recognized the potential effect on spherical aberration of the smaller mount throat (including the adapter "tube").

So again, the matter must be answered by practical observations.

Best regards,

Doug

[Asher Kelman]

It turns out that in high energy radiation into tissue, (or water), the edges of the field receive less scatter, as the scattered electrons from high energy photons hitting water build up away from the edge, as we go towards the center, until it plateaus off, as there, there are incoming scattered electrons coming equally from all directions.

With scatter of visible light photons, through spherical aberration, I guess that might be true too, but that one can design the outer lens curvature, (used only when the lens aperture is fully open), to also refocus some of the peripheral light, adding to a secondary plane of “crude defocus” causing a glow lined up with the dominant primary sharp plane of focus from the center of the lens.

Asher

[Jerome Marot]

Originally Posted by Doug Kerr

I'm not sure how it theoretically varies with distance from the center of the frame, or how it varies with distance from the center of the frame with a certain real lens.

I think that the traditional definition of spherical aberration is independent from distance to the optical axis. Aberrations which increase with distance from the optical axis and come from the spherical form of lenses are called astigmatism and coma.

From the point of photographic practice, coma is one of the worst aberration as to its visual effects. I refrained from talking about it, but maybe I should have. Wide angle lenses with spherical aberration often also suffer from lots of coma. So, in actual practice, lenses with a nice "glow" due to spherical aberration will also exhibit the problematic effects from coma.

This only affects wide-angle lenses, so presumably not a 229mm focal lens on a relatively small sensor.

[Jerome Marot]

Originally Posted by Asher Kelman

It turns out that in high energy radiation into tissue, (or water), the edges of the field receive less scatter, as the scattered electrons from high energy photons hitting water build up away from the edge, as we go towards the center, until it plateaus off, as there, there are incoming scattered electrons coming equally from all directions.

Certainly, but you are thinking about processes which do not use optics (e.g. X-ray imaging), while the aberrations we are discussing are a function of the shape of the lenses.

[Asher Kelman]

Originally Posted by Jerome Marot

Certainly, but you are thinking about processes which do not use optics (e.g. X-ray imaging), while the aberrations we are discussing are a function of the shape of the lenses.

I was thinking that some, (to me, as yet, unknown), amount of random scatter of visible light would also occur for light incident anywhere on a glass surface. This again would lead to a build up from the very edge towards the center. It might be that this is close to zero, as to be negligible or perhaps an amount that is significant, but in high quality glass that is uniform, you are probably right, it surely can’t be much.

As to Vaseline and lady’s stocking I have used them on a front “UV” filter many times with my film MF Bronica SQ. Just we forgot about that era!

Asher