CATLabs X Film 80 Characteristic Curve

[m00dawg]

Got it! Will give it a go and try to report back with my (super unscientific) results!

 

[m00dawg]

Ended up trying it out 9:00 at 20C and rating it at EI50. I used incident metering (these were portraits of the kiddo's first day of school). I think the negatives are about right. They scanned well, but I'll be printing them in the darkroom hopefully today (probably contact prints). By eye they look maybe still a bit thin to me but one of the places was lower in contrast. I think I should have used reflective metering and more properly evaluated the shadows.

 

[Bill Burk]

Adrian, did you hit the top of ISO parameter density within + or - 0.05 ? Looks like you hit high, which may even make 64 an optimistic rating.

Interesting that you found out by methodical testing that a film called by its manufacturer to be an 80 speed film, reveals to you that it is a 64 speed film.

You found a real speed loss, but just 1/3 stop.

Because you and others have found speed lower than the manufacturer, I would take some time to double check some sensitometry parameters like the light source (is it electronic flash or something like tungsten with an 80b filter?), the hold time (how long after exposing the test before you develop?), the developer (if you use D-76 stock, does the speed come up?). Do you “attenuate” the light source at all, and if so what is the spectral character of that material (For example I include a pair of Wratten 96 type filters for fast films which I admit is “wrong” for sensitometry). Differences in these sort of test conditions can give a slight variation in the test results. Maybe your lab setup didn’t “play into” the film’s strengths.

I know for example, Panatomic-X rates higher than 32 in my lab, while TMAX-400 and 100 rate as claimed within 1/6 stop. I figure that Panatomic-X likes daylight and electronic flash, and my lab plays to that strength.

To those who wonder why a film that tests to 64 should be recommended to be treated as 64 and 40. Why are we giving both exposure index (EI) numbers? My answer is that the higher number is for camera EI setting and incident meter EI setting while the lower number is for spotmeter EI setting ... if you are using Zone System metering (spotting the shadow and stopping down to “place the shadow on Zone III”).

If you want to do a sanity check when taking pictures, those two different EI used those two different ways might (mind you I said might) give you the same f/stop and shutter speed combinations.

Either way 64 is for minimum exposure for excellent printing. If you always prefer giving greater exposure to get open shadows you might choose to use EI 40 in a camera or incident meter with this film.

 

[Bill Burk]

p.s. Seeing all the discussion makes me think you are getting consistent results. Maybe you could do a run of CatLABS X film 80 in D-76 stock. And do a run of TMAX100 in D-76 stock for comparison. I don’t know the ISO hold time, but recommend after making the test exposure you hold for at least an hour. Developing right away tends to inflate speed.

 

[Adrian Bacon]

Adrian, did you hit the top of ISO parameter density within + or - 0.05 ? Looks like you hit high, which may even make 64 an optimistic rating.

Interesting that you found out by methodical testing that a film called by its manufacturer to be an 80 speed film, reveals to you that it is a 64 speed film.

You found a real speed loss, but just 1/3 stop.

Because you and others have found speed lower than the manufacturer, I would take some time to double check some sensitometry parameters like the light source (is it electronic flash or something like tungsten with an 80b filter?), the hold time (how long after exposing the test before you develop?), the developer (if you use D-76 stock, does the speed come up?). Do you “attenuate” the light source at all, and if so what is the spectral character of that material (For example I include a pair of Wratten 96 type filters for fast films which I admit is “wrong” for sensitometry). Differences in these sort of test conditions can give a slight variation in the test results. Maybe your lab setup didn’t “play into” the film’s strengths.

I know for example, Panatomic-X rates higher than 32 in my lab, while TMAX-400 and 100 rate as claimed within 1/6 stop. I figure that Panatomic-X likes daylight and electronic flash, and my lab plays to that strength.

To those who wonder why a film that tests to 64 should be recommended to be treated as 64 and 40. Why are we giving both exposure index (EI) numbers? My answer is that the higher number is for camera EI setting and incident meter EI setting while the lower number is for spotmeter EI setting ... if you are using Zone System metering (spotting the shadow and stopping down to “place the shadow on Zone III”).

If you want to do a sanity check when taking pictures, those two different EI used those two different ways might (mind you I said might) give you the same f/stop and shutter speed combinations.

Either way 64 is for minimum exposure for excellent printing. If you always prefer giving greater exposure to get open shadows you might choose to use EI 40 in a camera or incident meter with this film.

The setup is the same as what I used for fp4 except the camera. Electronic flash, metered to within 1/10 of a stop, then kept at that consistent power level. The reduce the light, the lens aperture is closed down. For 35mm film, I use a T-stop rated lens, for 120, I use a hasselblad 500C with the standard 80mm lens and stop the aperture down. In both cases, I have the lens focused at infinity and place the camera so that the grey card just fills the entire frame.

I’m not surprised that x-film is coming out at 1/3 stop less. I’m not using a t-stop rated lens, I’d expect that there’d be some light loss through the lens, and the flash is consistently +-1/10 of a stop.

Given that it’s only available as 120 and sheet, I doubt that there’s any through the lens metering systems, so 1/3 lower would be reasonable to account for lens light loss in 120 format. For sheet film, I’d still probably start at 64 and then factor in bellows.

 

[Adrian Bacon]

Adrian, did you hit the top of ISO parameter density within + or - 0.05 ? Looks like you hit high, which may even make 64 an optimistic rating.

I forgot, it’s a little high. I have a roll that I shot at 80, and ran for 9 minutes and everything came in a third lower. For the hold time, I shoot it, then process it within the hour. What’s standard practice?

 

[Adrian Bacon]

Interesting that you found out by methodical testing that a film called by its manufacturer to be an 80 speed film, reveals to you that it is a 64 speed film.

One last thing, CatLabs hasn't specified how they obtained the stated speed and what developer they used, or even if they went through that exercise. I suspect it's a little like with JCH 400. Its stated speed is 400, but it ain't a 400 speed film. It's 320 on a good day.

 

[Bill Burk]

Ok. So flash. That’s not the ISO standard light source but is a very good source substitute for testing, rules out shutter speed issue but could introduce reciprocity law failure for exposure shorter than 1/1000 second. EG&G that I use is also a flash, but it’s duration is 1/100 second so it avoids reciprocity law failure but still is a flash spectrum (spiky bars type of spectrum) rather than a tungsten (continuous smooth spectrum).

Drew Wiley would add that the gray card could affect spectrum and I would agree and categorize that impact as “bad as my No. 96 filters”.

Do you shoot a whole roll of individually-exposed frames for your tests? That’s a lot of work, Stouffer scales make such quick work, but I know you’re diligent.

Maybe just do a quick 120 test on a Kodak film to confirm test setup consistency between formats.

I don’t know the standard hold time. You would have to see the standard from Switzerland to get that. It might be two or three but one hour would be appropriate. I have seen a test summary and I think the result was that most immediate latent image loss occurs within about 15 minutes.

 

[Adrian Bacon]

Ok. So flash. That’s not the ISO standard light source but is a very good source substitute for testing, rules out shutter speed issue but could introduce reciprocity law failure for exposure shorter than 1/1000 second. EG&G that I use is also a flash, but it’s duration is 1/100 second so it avoids reciprocity law failure but still is a flash spectrum (spiky bars type of spectrum) rather than a tungsten (continuous smooth spectrum).

Drew Wiley would add that the gray card could affect spectrum and I would agree and categorize that impact as “bad as my No. 96 filters”.

Do you shoot a whole roll of individually-exposed frames for your tests? That’s a lot of work, Stouffer scales make such quick work, but I know you’re diligent.

Maybe just do a quick 120 test on a Kodak film to confirm test setup consistency between formats.

I don’t know the standard hold time. You would have to see the standard from Switzerland to get that. It might be two or three but one hour would be appropriate. I have seen a test summary and I think the result was that most immediate latent image loss occurs within about 15 minutes.

I’ve used a couple different flash units over time, my Paul buffs are crazy level short flash duration, though lately I’ve been using smaller units made by interfit that have a t.1 time in the 1/800 range. I’m sure the gray exposure card would effect spectrum. I’ve thought about using a white balance card as the one I have supposedly reflects the whole spectrum equally, but then I’d working with a different reflection level (it reflects ~70% as opposed to 18%) and that is just another layer of complexity that I’d rather avoid.

I shoot a whole roll. It actually takes me longer to process the film than it does to make the exposures as the only thing that changes from shot to shot is the aperture, and it’s no big deal to simply take a shot, advance to the next frame, close the aperture down by a stop, wash rinse repeat. I do one or more rolls to look at normal exposure down to film base to work out development times and get an approximate usable speed (I’m the first to admit that what I’m doing is an approximation) and to look at roughly what the bottom side of the curve looks like so I know about where the contrast inflection points are, then once that’s worked out, I’ll typically do one roll where I expose from normal to at least 7-8 stops above normal, or whenever I run out of strobe power to look at what the upper end looks like and roughly where it starts to shoulder off. My biggest light is 640 watt seconds, so I can hit the exposure card with a good amount of light. I start with the aperture closed all the way down and meter normal exposure, then progressively open the aperture up. Once it’s wide open, I’ll ramp the strobe power up in full stop increments until I’m at full power on the strobe.

From there, depending on what the curve looks like, I’ll either decide to make a specific scanning profile, or just use one of my generic ones and let the shape of the curve play through. It depends on what would look better. For something like JCH 400, because it’s such an extreme S-Curve, I did a specific one to straighten it out a little bit. On something like Fomapan 200, it’s so straight I just use a generic.

 

[Auer]

Pentax 645N | SMC Pentax-FA 645 80-160mm ƒ4.5 | Catlabs X Film 80 | Eco Pro Stock R | CS F96
75F | 8:30 min 60 sec inv | 20sec stop Eco Pro | 2 min fix



BLDG No 76 by Eric Auer, on Flickr