KODAK AHU technology: opinions, issues, reviews...

[Gautam Valluri]

On 12/2/2025 at 8:18 PM, Tyler Purcell said:

With AHU stock, we get back side scratching on all of them. We also have instability issues within the Aaton cameras specifically. I have done more scratch mitigation work than I've ever done before on these cameras. It seems like perhaps, the AHU stock creates more friction. 

Tyler, does the back side scratching show up in the image at all? And have you had any mag jams on the Arri SRs you've tested?

[Frederick Knauf]

Simon, 

In relation to your response: "You’re speaking of a new backside coating being applied to the backside of the base. I find that to be in contradiction to an Anti Halation Undercoat, a lightproof layer on the frontside of the base, underneath the photographic layers. Can you please clarify?" and Mark's explanation and drawing, which is spot on, let me explain.

Rem-jet, that black carbon slurry intermixed with a wax, served several purposes.  One was to block remaining light from bouncing off the back of the camera and exposing the emulsion a second time (anti-halation), and the other was to add protection and lubricity for conveyance in manufacturing equipment, cameras, and up-front lab handling where exposed negatives are nick checked and composited into larger rolls for processing.  Another benefit is that the carbon was a very good at spreading and reducing electrical charge which can build up on plastics with conveyance and winding. Thus, static discharge is nearly nonexisitent with rem-jet. 

With its removal, the light blocking anti-halation layer was moved to the interface between the emulsions and the plastic cellulose triacetate base.   This AHU layer could be made with gelatin and light absorbing dye or gelatin and unsensitized silver. The new AHU layer would be coated in the film emulsion coating process within Building 38, which provides amazing consistency and side to side uniformity, and because it is under the emulsion, still "qualifies" as an under-coat.

On the film base's back side, a new layer was added which is most similar to that found on the professional still film products.  That layer material was designed to impart both scratch protection through its lubricity and static charge dissipation through other propriatary materials intermixed.  

With these changes and in order to assure that the ECN-2 process remained consistent as far as time, temperature and agitation, the adding of an additional layer with a dense dark dye or silver underneath the light sensitive emulsions meant that the emulsion layers above required modification in thickness and amount of gelatin.  So, arguably, the new AHU films are new films with the same photographic characteristics as the older VISION3 rem-jet stocks.  I am confident that these films were thoroughly tested in all the ways prior to their introduction to assure that they would work well.

I hope this gives a little more insight into this significant change to the VISION3 family.

[Mark Dunn]

11 minutes ago, Frederick Knauf said:

a new layer was added which is most similar to that found on the professional still film products. 

Here's the potential contradiction. Stills film isn't transported at 90ft/min.

[Simon Wyss]

Thank you, Frederick, I am quite familiar with undercoats from Agfa Scala, Fomapan R, and other stocks from the USSR or the US, including the very first Kodak 16-mm. and Double-Eight films. It was just the wording over which I stumbled.

There’s a lot of knowledge in the public realm. One piece of it is that the Eastman-Kodak Company had discontinued the early black and white stocks despite they were good. Not good enough but good materials from the beginning. Of course do we all know that general sensitivity, the then ASA ratings, underwent a steady increase. When new standards were adopted in 1960 the level jumped up 100 percent. Besides that, and that’s what I actually want to pass on to Rochester, we have a lack of black and white films of low sensitivity, I mean at least one colourless-base panchromatic reversal film of, say, ISO 20. Or even less. An ISO 12 panchromatic negative film would also find buyers, I am certain about that. Cinema is a very technical phenomenon and it grows in the soil of fine mechanics and photochemistry. So, while we have colour negative stocks from ISO 50 to 500 we have nothing below ISO 100 in black. ILFORD Pan F plus is no longer available as MP conversion. Film-Ferrania P 30 is orthopanchromatic and also not available in long rolls. A Fomapan R 20 would be attractive. What are the thoughts at Kodak regarding a break up at last with the grey-base black and white stocks from the 1950s television era? I mean, you once had Panatomic-X reversal and that was wonderful.

[Tyler Purcell]

10 hours ago, Gautam Valluri said:

Tyler, does the back side scratching show up in the image at all? And have you had any mag jams on the Arri SRs you've tested?

No mag jams on the SR's as of this exact posting, maybe tomorrow at 9am I'll get one? 

Yes, the reason I started testing is because we started seeing weird scratches in scans. It started with tap scratches and then the more cameras I got in for scratching issues, I started to see a pattern. 

Edited December 4, 2025 by Tyler Purcell

[Tyler Purcell]

6 hours ago, Frederick Knauf said:

I am confident that these films were thoroughly tested in all the ways prior to their introduction to assure that they would work well.

Supposedly Kodak only tests 35mm perforated film and not 8mm or 16mm. 

35mm cameras are very different beasts. 

[Jon O'Brien]

3 hours ago, Tyler Purcell said:

Supposedly Kodak only tests 35mm perforated film and not 8mm or 16mm.

That would be for regular, usual testing, if so. But we're talking about a whole new type of VISION3 stock here. I'm sure Kodak would have tested the new AHU film in 16mm cameras. As you know, and as Kodak would know, professional film production often uses 16mm equipment. Let's all just breathe easy and maybe stop tilting at windmills. Worrying about potential problems or 'what could happen' doesn't sound very fruitful. Tyler, they are old cameras you are testing. Could this be a big factor?

Edited December 4, 2025 by Jon O'Brien

[Mark Dunn]

17 hours ago, Jon O'Brien said:

they are old cameras

Aren't they all "old" now?

 

[Tyler Purcell]

23 hours ago, Jon O'Brien said:

Let's all just breathe easy and maybe stop tilting at windmills. Worrying about potential problems or 'what could happen' doesn't sound very fruitful.

I'm the guy servicing the cameras, you're welcome to fly out here and see the problems yourself. 

[Jon O'Brien]

On 12/6/2025 at 2:17 AM, Mark Dunn said:

Aren't they all "old" now?

 

Yes, but some are very much more worn out than others. Just a thought.

Edited December 7, 2025 by Jon O'Brien

[Elena Bertelli Bianchi]

Hello everybody! Thank you all for your answers, I'm learning a lot.

A quick update: I am still working to the same production and I have to say that lately the issues I mentioned at first seem to be gone for now. Maybe it was just a period of adjustment, who knows. Early batches that still need to be perfected. 

@Tyler Purcell, we don't have scratch issues at the moment, not even "dirty gate" issues, but please keep us updated with your tests! The cameras I've been using with the AHU film are SR3 and ARRICAM LT.

On 12/2/2025 at 8:18 PM, Tyler Purcell said:

I have noticed the perforation holes also deflect easier, this is an issue I saw directly on the Aaton cameras with penetration on the lower side of the spectrum, something I use to do purposely to keep the quiet. Now you can't do that trick anymore, you have to run penetration up much higher. The AHU stock is thinner, not much but it is. I don't think the thickness is necessary the problem, but I do think the stock flexes MUCH MORE than the Remjet stock, you can feel it when you work with it as well, it just feels like a lighter weight material. I think the carbon coating of the remjet made the film deflect less.

Also, if you don't mind, can you explain this better please? What do you mean with "the perforation deflect easier"?

[Tyler Purcell]

19 hours ago, Elena Bertelli Bianchi said:

Also, if you don't mind, can you explain this better please? What do you mean with "the perforation deflect easier"?

I can make a video sure! 

But on some cameras like the Aaton's, the pulldown claw slides into the perforation as it starts its pulldown stroke. This process relies heavily on the perforation to have some semblance of stiffness. There is a pressure plate that holds the film against the pulldown, so that helps a lot. However, the deflection still does make a difference. You can see it through emulsion buildup in the cameras after use, especially in SR's and around the pulldown area on Aatons. I have now serviced 4 Aatons that have shot with AHU for more than a few rolls and all of them were caked with emulsion around the pulldown claw due to this deflection. They probably ran high speed and film couldn't handle it. 

I'm not sure what to do at this point, the film looks totally fine, but these problems are becoming more and more of an issue for owners. 

[Simon Wyss]

Imaginable that there will be less emulsion debris with stock that has aged a few months. Also to polish a claw’s contact surface may bring something. My 2 rubles