Slowest ISO today?

Grandpa Ron · Jan 21, 2020

I was reading Ansel Adams book on cameras and he mentioned working in the 1920's, with film speeds of 12 and 25 ISO (ASA back then).

I was curious if such slow speed films exist today and what they would be used for?

Soocom1 · Jan 21, 2020

Ilford make 25 speed, and Cine made up until a few years ago a 12 speed film.
At one point Kodak made a 6 speed sheet film for 4x5.
it was almost exclusively used for scientific, media copy/lithography, and still life-architectural use.
The shutter speeds were god awfully slow, but the images were unsurpassed in the hands of a competent photographer.

I shot some 25 speed sheet years ago and it was magnificent.

I know others will disagree but I wish they would put out a digicam at 6 ISO.

Soocom1 · Jan 21, 2020

Here: Cant read it unless subscription, but.. It tells you the stuff was made.

ISO 6:1993 - Photography -- Black-and-white pictorial still camera negative film/process systems -- Determination of ISO speed

vintagesnaps · Jan 21, 2020

Try Home - The Film Photography Project , they carry unusual films and slower speeds sometimes.

I have a Lego camera (just for fun, obviously, from a store that had them on closeout), I think the ISO is in single digits. You get a small image that probably won't enlarge much. Of course it has a dinky lens so you can only expect so much.

I've never used really slow speeds but have vintage cameras that have lower ASA/DIN options than later cameras, which probably indicates what speed films were made in the same era as the camera. So what Ansel Adams used that early probably only had somewhat slower speeds. Maybe he was doing longer exposures when set up to do landscapes, and I think the slower films would have had less grain.

dxqcanada · Jan 21, 2020

I used to shoot with Kodak Panatomic-X in my 35mm SLR. Great film for my speedy prime lenses. The resolution and contrast was awesome. I also shot with Kodak Kodachrome 25 ... again, resolution and contrast.
Both of these films are no longer made.
Ortho film is really slow ... was typically used to make masks, but I did shoot some large format stuff with ... not easy.
Ilford still makes Pan F Plus which is 50 ASA
Freestyle has some low speed stuff
and B&H

dxqcanada · Jan 21, 2020

I forgot to mention ... you have to anticipate using low shutter speeds, so typically it is tripod work ... but I did do a lot of street shooting when it was sunny outside.

compur · Jan 21, 2020

Rollei 25, Adox 20, Washi 12 and others.

Derrel · Jan 21, 2020

Good when in bright light...now that we have one eight thousandths of a second top speeds on many cameras and lenses that open as wide as f/1.4 or even F 1.2... its really handy to have slow speed film available as an option.

compur · Jan 21, 2020

One use for slow film is intentional motion blurs using slow shutter speeds.

Derrel · Jan 21, 2020

Slow film is also good for long, timed exposures.

earthmanbuck · Jan 21, 2020

As vintagesnaps mentioned, Film Photography Project does have some super-slow films for sale. They have one that is ISO 1.6 that I have used. The only camera I have that would allow me to use the built in light meter for it was my Nikon FE—I set it to 12 (the lowest available setting), +2 EV, and then opened it up an additional stop from whatever setting it told me was exposed correctly. I posted the below picture on the forum already, but that's the best example I have—most shots were still underexposed looking, and all have a fairly blue cast, kind of a cross-processed look.

To be fair, I was shooting everything handheld so I couldn't dip too low with shutter speed. I have another roll of it...when I shoot it I'll see what it can do with a tripod.

As far as other lower speed films go, 50 is not that uncommon, and I believe I've also shot a B&W 25 before with nice results.

Soocom1 · Jan 21, 2020

Remember that the slower speed film also is smaller in actual grain size. Hence the superior image quality.

IanG · Jan 22, 2020

The ASA/BS film speed standards were revised in the early 1960's by removing a sfety factor of 1 stop so overnight film speeds doubled

So Fp3 went from 64 ASA/BS to 125 ASA/BS. HP3 from 200 ASA/BS to 400 ASA/BS, PanF from 25 ASA/BS to 50 ASA/BS. It was the same with Kodak films as well. Sp when Adams mentions 12 and 25 ASA films in reality they would now be 25 & 50 ASA.

The ASA standard wasn't International so films sold here in the UK were marked BS (British Standard) as well.

Modern 100 ISO films are better than the 12 & 25 ASA films of the 1920's in all respects, finer garin, sharper, well hardened etc. Films improved dramatically in the 1930's with the introduction of Ilford Fine Grain Panchromatic (FP) and Hypersensitive Panchromatic (HP) films in 1934, Kodak lagged but nearly caught up with Pan-X, Plus-X, Super-XX, and Tri-X in 1938/9, but Ilford had already upgraded to FP2 and HP2 in 1937.

Ian