Eastman Kodak Diffusing disc

gorbas · Jun 15, 2022

Question for people familiar with Kodak LF lenses and accessories.
Is this disc marked: No2, F4.5 for the taking lens?
Was it Kodak answer to Dutto soft filters.
Many years ago I used it to soften prints in darkroom and it produced very nice effect used for 10-20% of total exposure time. I did not keep it stationary, always with small circular motion under the lens.

AgX · Jun 15, 2022

The idea behind the Duto filter was to use optical elements on flat pane. The inventors used concentric rings with a convex cross-section. You got convex rods arranged in a criss-cross pattern. Then there are als splattered convex lenses.
Likely there are more arrangements...

For each version one could contemplate on the effect, but testing would tell the truth.

gone · Jun 15, 2022

I'm glad I saw this. Rather than spend hundreds of dollars on a soft focus lens, maybe 2 or 3 of these $25 filters can give me a similar soft effect. I like the idea that you could make several prints and figure out which one worked best. With a soft focus lens, you're stuck w/ what's on the negative.

AgX · Jun 15, 2022

momus said:
I'm glad I saw this. Rather than spend hundreds of dollars on a soft focus lens, maybe 2 or 3 of these $25 filters can give me a similar soft effect.

Such filters with optical elements can have a different effect than typical soft-lenses.

gorbas · Jun 15, 2022

Yes, I forgot about Zeiss Softars and their dimples!

xkaes · Jun 15, 2022

gorbas said:
Question for people familiar with Kodak LF lenses and accessories.
Is this disc marked: No2, F4.5 for the taking lens?
Was it Kodak answer to Dutto soft filters.
Many years ago I used it to soften prints in darkroom and it produced very nice effect used for 10-20% of total exposure time. I did not keep it stationary, always with small circular motion under the lens.

This is discussed on page 305 of this document:

https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/505/WRussellYoungPhDThesis.pdf?sequence=6&isAllowed=y

JPD · Jun 15, 2022

Those lines (or circles on the Duto (Dulovits-Toth) one) produce one or more weak out of focus images on top of the sharp image, and that gives the softening effect. I haven't used the Kodak Diffusion Disc, but the Duto is meant to be used with large apertures, as the weak out of focus image sharpens up when you stop down. At small apertures you might even see rings on the photos...

mshchem · Jun 15, 2022

I've seen mention of Kodak diffusion disks in Kodak's darkroom equipment catalogs from the 40's and 50's. There was at least a couple of different types.
In the day Kodak had everything imaginable.

MattKing · Jun 15, 2022

mshchem said:
In the day Kodak had everything imaginable.

Including my Dad working at the order desk in Toronto

mshchem · Jun 16, 2022

MattKing said:
Including my Dad working at the order desk in Toronto

And based on his son, I bet he was an essential asset for EKCo. I'm sure you know, these processing lines, not really more than 6 or 7 in North America were state of the art. I ALWAYS specified Kodak processing. I shot Kodachrome, Ektachrome and Ektacolor S. I have Ektacolor prints, both RC and fiberbase Kodak prints that are still in great shape.

MattKing · Jun 16, 2022

Actually, Canadian Kodak - not Eastman Kodak.
And Dad's order desk time was right at the beginning, right after he left the RCAF, before he became middle management and long before he was transferred out to British Columbia to help staff and run the new Kodachrome and Ektachrome lab there.
During his time on the Order desk, professional customers and dealers either telephoned or mailed in orders, and the order desk staff worked from large in-house catalogues to fill them.
Dad's telling of his story about dealing with Karsh and a screwed up order amazed me when I first heard it.

Bob S · Jun 16, 2022

momus said:
I'm glad I saw this. Rather than spend hundreds of dollars on a soft focus lens, maybe 2 or 3 of these $25 filters can give me a similar soft effect. I like the idea that you could make several prints and figure out which one worked best. With a soft focus lens, you're stuck w/ what's on the negative.

No, a soft focus lens diffuses the highlights into the shadows.
a soft focus attachment, Softar, Dutto, etc. diffuses the shadows into the highlights. The opposite effect.

AgX · Jun 16, 2022

Bob S said:
A soft focus attachment, Softar, Dutto, etc. diffuses the shadows into the highlights.

I would not know how such is possible.

Thr difference rather is what effect specular lights have

MattKing · Jun 16, 2022

Bob S said:
No, a soft focus lens diffuses the highlights into the shadows.
a soft focus attachment, Softar, Dutto, etc. diffuses the shadows into the highlights. The opposite effect.

AgX said:
I would not know how such is possible.

Thr difference rather is what effect specular lights have

The Disk in question is used at the printing stage, not the exposing stage. It diffuses the light from the low density portions of the negative into the light from the high density portions of the negative - i.e. subject highlights into subject shadows.

AgX · Jun 16, 2022

But this is a matter of use. Moreover, Bob had it at filters/attachments marketed for and typically used at taking.

By the way, thank you for hinting at the darkroom use of thar Kodak attachment. I was not aware of it, as here hardly ever such attachment was marketed or proposed. (And non-film, non-german Kodak stuff also was practically inexistent.)

MattKing · Jun 16, 2022

Looking at the thread again, I may have misunderstood the Disk's use. If I was right, and it was used in the darkroom, not on the camera, than my explanation makes sense.
If the Disk was used on the camera, ignore everything I posted

xkaes · Jun 16, 2022

AgX said:
By the way, thank you for hinting at the darkroom use of thar Kodak attachment. I was not aware of it, as here hardly ever such attachment was marketed or proposed. (And non-film, non-german Kodak stuff also was practically inexistent.)

There are lots of soft-focus attachments and they create their effect in many different ways. Some are designed for use on the camera, while others are designed for use on the enlarger, Others can be used on either -- with the same or different results. And some assume certain conditions. For example, the SOFTARS are great for wide-open, portrait length lenses, but horrible for stopped down or wide-angle lenses. So it's important to run some tests.

gorbas · Jun 16, 2022

Ok, I had to dig out my 1946 Kodak lenses data book.
There were 3 different Diffusion attachments:
Kodak Pictorial Diffusion disc for camera lenses
Kodak Portrait Diffusion disc for camera lenses with build in diopter for closer focus and
Kodak Diffusion disc for enlarger lenses
So, maybe #2 is the strength of attachment, not the # lens?
No idea why there is F 4.5 marking?
Attaching is with some kind of bayonet mount.
There is Kodak Canada sticker on it and patent day, March 8th, 1921

Bob S · Jun 16, 2022

xkaes said:
There are lots of soft-focus attachments and they create their effect in many different ways. Some are designed for use on the camera, while others are designed for use on the enlarger, Others can be used on either -- with the same or different results. And some assume certain conditions. For example, the SOFTARS are great for wide-open, portrait length lenses, but horrible for stopped down or wide-angle lenses. So it's important to run some tests.

Softare were only made by Zeiss and we’re sold under license by Rollei, Hasselblad, Heliopan, etc. the unique benefit of the Softar is that their effect did not change with apertur. On the other hand copies from the Far East did cange effect with aperture.

AnselMortensen · Jun 19, 2022

Judging from the Kodak info posted above by Gorbas, the diffuser is intended for use on an enlarging lens.
I have one as well, a #2...

Now I have to try it out in-camera.

choiliefan · Jun 20, 2022

I too have a number two and perhaps a three in a box somewhere. Mine has a small knurled knob-screw to secure it to the enlarging lens.
The higher the number, the greater the diffusion.

grat · Jun 27, 2022

AnselMortensen said:
Judging from the Kodak info posted above by Gorbas, the diffuser is intended for use on an enlarging lens.

I read it the other way-- it's intended for camera use, but can also be used on the enlarger to produce a soft image. Based on the descriptions, I suspect the pictorial diffusion disk would produce some odd artifacts on an enlarger, whereas the portrait disk wouldn't.

I have an exceptionally clean pictorial diffusion disk that I'd like to try, but as near as I can tell, it's series 7.5, which makes it about the most unusual format out there. Finding any kind of adapter has been frustrating to say the least.

choiliefan · Jun 28, 2022

Interesting that Kodak referred to the diffusion TAKING filters as disKs and ENLARGING filters as disCs:

https://www.pacificrimcamera.com/rl/00019/00019.pdf

AgX · Jun 28, 2022

Obviously one text was written in Rochester, the other in Harrow...

Actually I always have a problem with spelling this word and repeatedly had to look it up at Kodak catalogs, yesterday again, for this diffusor.

choiliefan · Jun 28, 2022

I'm curious if the two types of filters and engraved respectively as Disk or Disc. As I read the catalog, the taking filters will be labeled A or B. The enlarger filters will be numbered on the filter barrel as opposed to lettered.

Eastman Kodak Diffusing disc

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