Cameras that read 40 & 160 ASA and Tri-X

[jimmyking]

Hello,
Is it OK to expose Tri-X as 160 ASA in Super-8 cameras that only read 40 & 160 ASA and don't allow compensating?
I'm planning to shoot some scenes with a tiny Rollei SL-86.

[MIKI-814]

Tri-X exposed at 160 instead of 200 is ok from my experience. It'll only be overexposed 1/3 of f-stop.

[Muckymuck]

In my experience, Plus X also looks great if exposed in a 40/160 only camera, even when it's a G type which will expose it at 160 whenever the filter is out.

[Jim Carlile]

There's a little wrinkle to this.

The Rollei is an older early 70's camera. It might be what's called SMPTE compliant. Not sure about this-- they were made by Bauer, and some of those were, some were not.

What this means is that it is possible that the Tri-X speed [edit] notch will be read as 160 ASA, but the notchless cartridge might set the meter to ASA 100. Don't ask why this is-- it's long and complicated, and has to do with giving cameras the ability to read daylight films with their unusual ASA speeds.

If this happens, the Tri-X will be overexposed almost a whole f/stop. It all depends upon how high the Rollei will read ASA speeds. If it only goes to 160, you might have a problem with Tri-X. Moving the daylight filter back and forth won't solve it, either.

You just have to try it out. If it is SMPTE compliant, Plus-X will work fine. I have a sneaky feeling that it is, because of its age.

There is a way to test the camera, both with and without film, but it's too complicated right now to get into.

[jimmyking]

Thank you very much for your advice Jim! However I don't quite understand what you mean by notchless cartridge. Isn't the Tri-X notched as 200/160 ASA? Should I test the camera with the daylight filter engaged? In the manual it states: Super-8 film speed 17 or 23 DIN / 40 or 160 ASA. With black and white filming in daylight or artificial light move filter slide up (filter is moved out of the way).

[Jim Carlile]

Thank you very much for your advice Jim! However I don't quite understand what you mean by notchless cartridge. Isn't the Tri-X notched as 200/160 ASA? Should I test the camera with the daylight filter engaged?

Hey JK,

Tri-X is speed notched at 250 ASA, even though it is rated at 200. There is no 200 ASA notch. Your camera cannot read 250 ASA, so hopefully it will read Tri-X at 160-- that is as high as your camera will go. But it's still OK.

Tri-X is a daylight film, so you don't need to use an 85 filter with it. In fact, Kodak doesn't want you to use it, so they package it in what's called a "notchless cartridge." This pushes in a little pin in most cameras that disables the 85 filter, to make sure you can't use it. Even if you slide the filter switch to "sun," when the pin is pushed in, the filter is removed.

With tungsten films, there's a little notch in the bottom of the cartridge that leaves this filter pin out. That way you can decide if you need the 85 filter or not. But when the notch isn't there, like with Tri-X, you have no choice. The pin is always pushed in. No matter how you move the filter switch, you can't have the 85 filter in place.

So why does Kodak do this? Well, Tri-X is a fast film at ASA 200. If you use the 85 filter, it lowers the effective film speed to 125 ASA (actually, 100.) In Kodak's view, this defeats the purpose of the fast film, so they make it impossible to use the filter in the camera.

Some cameras do not have this filter pin, so the notchless cartridge makes no difference. I'm not sure about the Rollei, but I think it does, because it is an older camera. Also, because it is older, if the notchless cartridge pushes the filter pin in, there is a good chance the meter will register the film at ASA 100, rather than 160.

That's because Kodak designed this into the super 8 system so we can use daylight films rated at 100 ASA. That's how Ektachrome 100D works. It's how some cameras are able to set the meter for 100 ASA. It's part of the technology in many cameras. But it causes complications. It's not good for Tri-X, so you just have to experiment to see what your camera does.

In the manual it states: Super-8 film speed 17 or 23 DIN / 40 or 160 ASA. With black and white filming in daylight or artificial light move filter slide up (filter is moved out of the way).

I hear that some cameras, like the silver Nizos, will read daylight films at two ratings. In the case of Tri-X, they will read it at either 160, or 100. In other words, some of these cameras will automatically read Tri-X at 100, like I said above, because the filter pin is always pushed in by the notchless cartridge. But they also give you the ability to toggle back and read the film at the correct 160 if you want to. You do that by pushing the filter switch back.

This avoids the complications of a daylight cartridge that is rated high but the camera insists on reading lower, because of the super 8 system.

With the Rollei I am not sure. It may not do this. If not, the only reason why your camera manual says use the filter is because in the old days, Plus-X had a filter notch. That's when it was rated at ASA 50. The new Plus-X is notchless, so you cannot use the 85 filter switch.

Why did they change it? Well, because Plus-X is now 100 ASA, the camera needs to read it accurately. Even though there is a 100 ASA speed notch, few films ever used it, so most cameras cannot read this notch. So, what Kodak does is notch the new Plus-X at 160 ASA. Then, because they made the cartridge notchless, this pushes in the filter pin, which tells most cameras to rate the film at 100 ASA. But not all-- some cameras do not rate Plus-X accurately. They read it at 160. But that's another story...

Incidentally, for cameras that will read the 250 ASA speed notch, the Tri-X cartridge will push in the filter pin, telling the camera to rate the film at a 2/3 stop lower rating, which is about 160. That's the same thing that is happening with the 160/100 cameras. That's how those cameras read Tri-X at 160 even though it is speed notched for 250.

So why didn't Kodak just speed notch Tri-X at 160? Apparently, the philosophy was that a little overexposure in cameras was better than a little underexposure. Also, because they had already made the decision to totally disable the 85 filter, the more advanced cameras would still ruin Tri-X by exposing it at 100. At least with 250 some cameras would rate it close to exact, at 160.