Fujinon soft focus disk question

Are the soft focus disk for the 180mms and 250mm lenses the same size/interchangeable?

No. The disks for the 180mm are smaller. There are two disks - red and yellow, and they fit onto the rear of the front cell. The 180mm is in a Copal 1 shutter, while the 250mm is in a Copal 3S shutter.

Kumar

And the discs are rarer than hens teeth to find !

I have the 250mm with a red disc but want the yellow .
Having given up looking I have got a piece of metal that I have had cut so size and the main central hole also cut to what I think the centre size should be .
It larger than the red disc's .
I'm going to drill the 24 other holes on my bench drill .
Hopefully it should give a better effect than the red one .
If your looking for one of these lenses , make sure you get one with the yellow disc at least .

I have the 180 mm with the yellow disk and am tired of opening chicken mouths. Was hoping to expand possible solutions to the missing red disk.

Try calling the large format expert at Midwest Photo Exchange. At one time he could provide the discs. I forgot his name, though. Maybe it was Jim?

I've made my own out of black construction paper for other lenses. Cutting it to size is the hard part, but if you use a compass with a cutting blade attachment and take careful measurements, it's not too bad. Installing them is easy. You just unscrew the lens element and place it on top of the aperture. There's usually a lip that runs around it, so as long as you make it a tight fit, it won't move around so long as you don't jostle the lens too hard. To calculate the aperture, you just add the surface area of all of the holes and compare that to the surface area of the various marked aperture openings of the shutter. It takes a minute of math, but it's not hard math.

What I did was to design the (250mm yellow) disk in Thinkercad and 3D-printed it. I based the design on photographs from listings on the auction site and measurements of an actual lens. It was rather straightforward and I had a 3D printer available at that time.

Here are some dimensions for the disc set supplied with the Fujinon SF 1:5.6/250 #781350. These were measured with dial calipers, and ball-end small-hole transfer gages for the small holes.


The discs are made of aluminum alloy painted dull black. The measured dimensions (includes paint thickness) are:

Material thickness = 0.020” = 0.50mm

Outside diameter = 2.0127” = 51.12mm ϕ

Inside diameter of flanged edge (not across griping tabs) = 1.9647” = 49.90mm ϕ

Length over flange = 0.201” = 5.11mm (measured along the outside diameter)


Yellow-spot identification disc (large holes): The yellow spot is a 3.5mm diameter circle of thin plastic held to the disc with adhesive and is mounted between adjacent holes in the outer ring of holes (larger holes).

Center hole = 0.9288” = 23.59mm ϕ

There is an outer ring of 12 equally-spaced holes of diameter 0.155” = 3.94mm ϕ form a circle of 1.4888” = 37.82mm ϕ.

The inner ring of 12 equally-spaced holes are on radial lines midway from those of the outer ring. The diameter or the smaller inner holes is 0.133” – 0.134” = 2.38mm ϕ – 3.40mm ϕ. The centers of these lie on a circle of 1.141” diameter = 29.98mm ϕ (probable 29mm ϕ).


Red-spot disc (smaller holes): The red identifying spot is 3.5mm diameter plastic sticker as with the yellow-spot disc. The holes are in two rings as is the yellow-spot ring.

Center hole = 0.778” = 19.76mm ϕ

The outer ring is composed of 12 holes of 0.115” diameter = 2.92mm ϕ whose centers lie on a circle of 1.38” diameter = 35.05mm ϕ.

The 12-hole inner ring has holes of diameter 0.089” = 2.26mm ϕ and whose centers lie on a circle of 0.985” diameter = 25.02mm ϕ.

I don't like the tea strainer discs. I don't care for the effect with the small holes opened with either the Fuji SF or Rodenstock Imagon lenses. I prefer to use the apertures built into the shutters.

davidmasek said:

What I did was to design the (250mm yellow) disk in Thinkercad and 3D-printed it. I based the design on photographs from listings on the auction site and measurements of an actual lens. It was rather straightforward and I had a 3D printer available at that time.
View attachment 195900

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Who can help me please ? I'm desperately looking for soft focus discs for my fuji fujinon 180 sf. if i could have a simple copy with the scanner of both (red & yellow) that would be fantastic. The exact height & diameter would also be helpful. My son has a 3d printer and would print the soft focus discs for me, but i have no measurements ...
In the hope of an answer best regards ralph
tewifa@gmail.com

Post 8 gives measured dimensions for the 250 disks. If you want to try, I can send a scan of the two 250 disks and you can try scaling down to the 180 diameter. Just guessing, but that might be close enough.

somewhere in the world, probably with lost paper clips, are 180 disks. They are indeed hard to find!

BrianShaw said:

Post 8 gives measured dimensions for the 250 disks. If you want to try, I can send a scan of the two 250 disks and you can try scaling down to the 180 diameter. Just guessing, but that might be close enough.

somewhere in the world, probably with lost paper clips, are 180 disks. They are indeed hard to find!

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I am thankful for every help !! I've only been in medium format for a short time and am currently building a 4x5 from Edgar Kech, that's how I got the fuji 180 fujinon sf.
Kind Regards Ralph

davidmasek said:

What I did was to design the (250mm yellow) disk in Thinkercad and 3D-printed it. I based the design on photographs from listings on the auction site and measurements of an actual lens. It was rather straightforward and I had a 3D printer available at that time.
View attachment 195900

Click to expand...

Any chance you can share the file?

But also agreed that these lenses don’t NEED a strainer to work. They are hugely soft. And the strainer is a way to mix in supersoft outer area of the lens with the sharper center and maximize the halo size over a more defined image. Kodak portrait is like the Imagon in formula, but uses no strainer. Same with Congo SF (no strainer) and Fuji SF.