Eastman 2366 ISO 6 Blue-Sensitive B&W Film Review

Eastman 2366 ISO 6 Blue-Sensitive B&W Film Review

2000 1125 Sroyon Mukherjee

ISO 6 black-and-white film: “Cool.” Sensitive to blue light only: “Seriously?” Custard-yellow film base: “Take my money!” That, more or less, was my thought process as I stood in the bookshop of the Photographers’ Gallery in London, holding a 35mm roll of Eastman 2366 – the weird and wonderful film which is the subject of this review.

Eastman 2366 is an ultra-slow black-and-white film with low (virtually invisible) grain, high acutance and high resolution. It’s perhaps not the ideal film for an absolute beginner or someone using a point-and-shoot camera – the low ISO and blue-sensitivity pose some technical challenges, but they also combine to create a unique look and open up some fantastic creative possibilities.

Origin and Availability

Eastman Fine Grain Duplicating Positive Film 2366 – Eastman 2366 for short – is a “duplicating film intended for making master positives from black-and-white camera negatives” (according to Kodak’s datasheet). In other words, ordinary black-and-white negatives can be “contact printed” onto Eastman 2366 film to produce master positives. Those positives, in turn, can be contact printed onto some other film – Kodak suggests the sister film, Eastman 2234 – to produce any number of duplicate negatives.

The duplicates thus produced, according to Kodak, “are only distinguishable from the originals by skilled observers”. Traditionally, machines such as the Bell & Howell Continuous Film Printer (pictured below) would be used to duplicate large quantities of film, using the process described above. But the film can also be loaded into 35mm cameras and used (within limits) for regular photography.

Eastman 2366 is only available in 35mm format. Bulk rolls can be purchased on special order from B&H. But thankfully for casual users like me, it’s also available in smaller quantities, conveniently packaged in 35mm canisters. The roll I got from the Photographers’ Gallery, a 36-exposure roll with the blue packaging which I really like, is distributed by a Spanish company called Foto-R3.

[FPP Film image courtesy Analogue Wonderland]

[Bell and Howell Printer image courtesy Brian R Pritchard]

Eastman 2366 is also sold by the Film Photography Project under the name FPP Low ISO Black & White (24-exposure rolls). In the UK, it can be purchased from Analogue Wonderland (though I’ve only shot the Foto-R3 version myself). FPP also offer another ISO 6 blue-sensitive film, but that one is manufactured by Svema and easily distinguished by its lavender base (blue-sensitive film and snazzy film bases seem to go hand in hand).

Trial Run

Other than a helpful review by Alex Luyckx, I could find very little information online about using Eastman 2366 for straight photography. I was nervous about shooting the whole roll in case it turned out that I had completely misjudged exposure or development, so I decided to do a kind of clip test: I would shoot about ten frames, cut that part of the roll from out of the camera (inside a changing bag of course) and develop it.

Accordingly, I loaded the film into my Leica M3, finished work early on a Friday and went out to take some pictures. But by the time I started, the shadows were getting longer – not the ideal conditions for shooting an ISO 6 film! On top of that, I was using a 50mm Summicron f/2 from 1956 which, as much as I love it, is not very fast by modern standards. Even at maximum aperture, my shutter speeds were too slow for handheld photography. You can see a hint of camera-shake in the photo of the gas cylinders (shot at 1/15 sec), and more than a hint in the close-up of the stray dog (1/8 sec).

But in the photo of the birds, panned at 1/15 sec, the slow shutter speed made for a nice, dreamy effect. I printed two copies in the darkroom and toned one of them in black tea. Somehow, using an unusual film stock seems to inspire more experimentation in general – at least it does for me.


Unlike more mainstream film stocks, Kodak’s datasheet for Eastman 2366 does not provide a recommended developing time. It does, however, say that the recommended control gamma is 1.2 to 1.6 (gamma being a measure of film contrast). I thought I’d aim for a gamma of 1.4, being in the middle of the recommended range. According to the datasheet (the inset graph on page 2), the corresponding development time for Kodak D-96 developer is around 6:20 minutes at 21°C (70°F).

However, I did not have D-96 at home – instead I was going to use ID-11 diluted 1+1 – and the datasheet did not give times for any other developers. So I found a different film stock on the Massive Dev Chart, namely Kodak Double-X, which has times for both D-96 and ID-11 1+1. I then reasoned as follows: according to the Massive Dev Chart, Kodak Double-X rated at ISO 250 can be developed in (a) D-96 for 7 minutes at 21°C (70°F), or (b) ID-11 1+1 for 10 minutes at 20°C (68°F). So Kodak’s recommended development time for Eastman 2366 in D-96, namely 6:20 minutes at 21°C (70°F), roughly translates to 9 minutes at 20°C (68°F) in ID-11 1+1.

Clearly, this is not a very scientific way to determine development times. But I sometimes follow this strategy when I can’t find published times for a given film/developer combination, and so far it has worked for me (film is forgiving like that). Besides, the clip test I did with the first ten frames shot on my Leica showed that my guess (9 minutes) was not too far off. I used the same times for the rest of the roll.

My negatives did turn out quite contrasty, but I think the film is just designed that way. Kodak’s recommended control gamma for Eastman 2366, as I mentioned, is 1.2 to 1.6, while for Kodak Double-X it’s only 0.65 to 0.70 (higher gamma indicates greater contrast).

If you didn’t follow all that, don’t worry. The TL;DR is that I developed Eastman 2366 in ID-11 1+1 for 9 minutes at 20°C (68°F).

Exposing Ultra-slow Film

When I texted my friend, who’s relatively new to film photography, to say I was shooting an ISO 6 film, her reply made me laugh: “6????? Are you insane??? Are you shooting into the sun???? Entirely with a tripod???”

A few years ago, I’d have reacted the same way, but of late I’ve been making pictures on enlarging paper rated at ISO 6 on a homemade pinhole camera, so slow film doesn’t faze me. If anything, being able to use a fast lens as opposed to a pinhole with an effective aperture of f/180 feels like a luxury.

That said, after the ten test frames, I switched to a Minolta X-700 for the rest of the roll. I have an MD Rokkor 50mm f/1.4 lens for the Minolta, and I realized that with super slow film like Eastman 2366, the one additional stop would be a big advantage over the 50mm Summicron f/2 which I used for the test.

In fact, with a fast lens, and in India where the light is good even in winter, ISO 6 is surprisingly usable. Most of my roll was shot without a tripod. If you think about it, even in “heavy overcast” weather the sunny 16 rule suggests f/5.6 and a shutter speed of 1/6 seconds. This is equivalent to f/1.4 and 1/100 seconds, which is totally feasible for handheld photography. On the plus side, even in broad daylight and without recourse to a neutral-density filter, you can take portraits with shallow depth-of-field or stop down for creative use of motion blur.

Of course, there are some limitations. ISO 6 can be a problem if your camera’s ISO dial doesn’t go down that far and there’s no manual option. The Leica M3 is fully manual, so I was simply using a light meter app set to ISO 6 and manually dialing in the exposure. The Minolta X-700 also has a manual option, but I used aperture priority; I set the ISO dial to the lowest setting (ISO 25) and used +2 exposure compensation, effectively rating the film at ISO 6.

My usual approach to exposure is quite slapdash. I rarely bracket, and with some of my meter-less cameras I frequently “guess the light.” I mostly get away with it because I typically use Ilford HP5, which is a forgiving film with plenty of latitude. But with Eastman 2366 I was a bit more mindful, since high-contrast film needs extra care not to completely crush the shadows or blow the highlights. I used a meter as I mentioned – a phone app with the Leica and TTL metering on the Minolta – and at times I also compensated or bracketed (I’ll come back to this after I discuss blue-sensitivity, since the two are interrelated).


Low-ISO films – offered by Adox, Washi and Lomography amongst others – are a fun niche within the already niche pursuit that is film photography. But until my encounter with Eastman 2366, I had never shot, or frankly even heard of, a blue-sensitive film. So before shooting this film, I proceeded to do some research.

To state the obvious, the resulting images are still black-and-white. However, ordinary black-and-white film, also known as panchromatic film, is sensitive to the full spectrum of visible light. Orthochromatic films – like Ilford Ortho Plus and Rollei Ortho 25 – are sensitive to violet, blue, green and (to some extent) to yellow light, but not to red. So compared to panchromatic film, orthochromatic films render blue skies lighter, and red lips darker.

Blue-sensitive films like Eastman 2366 are basically an extreme version of orthochromatic film, being sensitive to violet and blue light only. In the graph below, I overlaid the spectral sensitivity curves of (a) Eastman 2366 and (b) Kodak T-Max 100, a modern, panchromatic black-and-white film, onto a representation of the visible spectrum.

Evidently, T-Max 100 is sensitive to almost the entire range of visible light, whereas Eastman 2366 drops off dramatically in the blue part of the spectrum (a typical orthochromatic film would fall somewhere in between). Incidentally, Kodak have another specialized film, Eastman 5302, which is sensitive to an even narrower range of blue light.

Of course, blue objects reflect blue light, and white objects reflect all colors of light, including blue. But this does not mean that blue-sensitive films can only “see” blue or white objects. Most other objects also reflect various wavelengths of light to greater or lesser degrees. For example, a green leaf predominantly reflects green light, but typically it will reflect smaller amounts of blue, yellow and red light as well. In the image of the broccoli above, the spot has RGB values of (100,150,50) as measured by the eyedropper tool in Photoshop. Green dominates, but red and blue are also present.

Still, blue-sensitivity does have a clear impact on photographs. Objects which reflect more blue light appear lighter, while other colors look darker than normal. In the earlier photo of the cityscape, the foliage looks darker, which adds to the dramatic effect.

But to see the effect of blue-sensitivity in its full glory, I took a couple of photos where I thought it would be especially evident. I then took the same photo with my DSLR, in color, and converted the DSLR image to greyscale using the desaturate command in Photoshop. I’ve labelled the images for easy identification.

As you can see, the blue-sensitivity of Eastman 2366 has a dramatic effect. In the desaturated digital images, the tonal values of the white and yellow chrysanthemums are fairly close, but on Eastman 2366, the yellow chrysanthemum looks nearly black. (A similar effect could be achieved by digitally manipulating the color image: discarding the red and green channels and desaturating the blue channel only.)

In the photo of the vegetables, Eastman 2366 “inverts” the tonal relationships, making the aubergines lighter and the tomatoes darker – the opposite of the desaturated digital image.

The light source plays a part as well. I shot the entire roll in daylight, with the exception of the shower photo which was a combination of daylight and fluorescent light. I would not recommend shooting Eastman 2366 in tungsten light (or, for that matter, with a yellow filter) since the film has little or no response to yellow light.

Exposure Compensation and Bracketing

Taking the blue-sensitivity into account, I exposure-compensated or bracketed some of my photos, depending on the color of the subject. The film “sees” blue subjects better than the meter predicts, so I underexposed to avoid blowing them out. Conversely, if the main subject was red, green or yellow, I overexposed to avoid losing shadow detail.

Shown below are my reference photos (digital) in color, and contacts prints of the bracketed exposures.

The first film photo of the blue idol, with no exposure compensation, blew out some details on his face. The second photo, with –1 stop exposure compensation, produced a better result, closer to what I was looking for.

I overexposed the photos of the tomatoes, since Eastman 2366 does not “see” red light. The first frame, a +1 stop exposure compensation, produced a good result. Because I wasn’t sure if +1 stop would be enough, I also took one at +3 stops. That, clearly, was too much.

The first photo of the idol is salvageable with post-processing or in the darkroom, but the second photo of the vegetables is blown beyond repair. Eastman 2366 is a high-contrast film with not much latitude (at least, not with my way of processing; I haven’t tried other ways). So I would recommend bracketing, especially for trickier situations where the subject has a lot of blue or red.

Film Base

Eastman 2366 has a clear ESTAR base (ESTAR is Kodak’s trade-name for polyester). Most 35mm films for still photography, like Kodak Tri-X and Ilford HP5, have a triacetate base. Polyester film like Eastman 2366 is stronger, stabler and more durable. But its strength can pose a practical problem: if the film-advance mechanism jams and you force it, triacetate film will break, while polyester film can damage the camera itself.

Kodak’s datasheet states that Eastman 2366 has “high resolution and … very high acutance” (I haven’t personally tested this or compared with other films, but it’s not surprising since the film was originally designed for duplication of negatives). The film incorporates a yellow dye which is removed during processing (hence the color), and the non-emulsion side has an anti-static layer with a carnauba wax lubricant.

The film base is extremely clear and has a slight yellow tint, perhaps a residue from the dye. Perhaps this would go away if I washed it longer, but the tint is so faint that it doesn’t have any perceptible effect on scanning or printing. Below you can see a comparison with Kodak T-Max 100, which a triacetate base and a faint purple tint.

I also took an extreme close-up to show the grain, or lack thereof. The little spots you see are tiny dust particles; the grain itself is basically invisible – the joys of ISO 6 film. When printing my photo of the two birds in flight (shown above), I actually had a hard time focusing my enlarger. There are no sharp details in the photo itself, and the grain is so fine that even with a focus magnifier, I could barely make it out.

And finally, a couple of caveats: since the film has a clear base, it should be loaded in subdued light or indoor light to avoid light piping. I also find that dust and water spots show up more prominently on a clear base, so that’s another thing to watch out for.

Final Thoughts

When I first encountered Eastman 2366, I was sufficiently intrigued that I bought it on the spot. The relative lack of online information and sample photos made me a bit nervous at first, and I wondered if I would end up regretting the impulse purchase. But my “clip test” with the first ten frames gave me confidence, and I’m really pleased with the final results. I’m currently in India where this film is difficult if not impossible to procure, and if anything, I regret not buying a few more rolls of this beautiful and truly unique film when I had the chance.

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Sroyon Mukherjee

Sroyon is an amateur photographer who likes making images with pinhole cameras, smartphones and everything in between. He also enjoys working on collaborative projects, alternative processes, and developing and printing in the darkroom.

All stories by:Sroyon Mukherjee
  • Wow, a lot of technical detail in this article. All good stuff. Nice photos too.

  • Avatar
    Charlotte – 35mm February 22, 2021 at 5:12 pm

    Really interesting article! Thanks for the clear explanation of the colour sensitivity too – my knowledge of this kind of thing was woefully basic (red filter = black summer skies), but this made a lot of sense! Would love to pick up a roll or two if I see it around.

    • Haha I was in the same boat not too long ago haha. But it’s simple once you think about it, and in a sense red filter=black skies is all there is to it – though the principle can be used for so many other things like manipulating other tonal relationships as well.

      I find the curves tool in Photoshop or similar software is actually a nice way to understand the effect of filters. Like take a colour image (phone pic or whatever), suppress the G and B channels, desaturate the red, and you get a red filter effect. Hope you get a chance to try this film, and thanks for your comment!

  • One more time, simply great ! 😉
    Thank you so much.
    I have to try one day, and now I have all the informations I need with great tests. I will use de M3 too.
    When I start to read I do not see who has writen, but when I have seen the Leica M3, I return to the top, to confirm that this great review is from you 😉
    Your M3 is great.

  • What a great post and review, now I want to try some. I also liked how you explained it all so clearly. Thank you.

  • Yay! I am very curious to see results because I’ve found very few samples online. If you end up trying the film and are happy to share, please email me (sroyonmukherjee [at] gmail [dot] com) or message me on Instagram (@midtonegrey), I would love to see.

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Sroyon Mukherjee

Sroyon is an amateur photographer who likes making images with pinhole cameras, smartphones and everything in between. He also enjoys working on collaborative projects, alternative processes, and developing and printing in the darkroom.

All stories by:Sroyon Mukherjee