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Weird idea: including greyscale pre-exposed on negative


jeffery_pool

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I was just waiting for some negs to dry and I had a thought. Bear with me

cause I'm definately not a technician...

 

Wouldn't it make sense for film manufacturers to include a step wedge on the

normally unexposed portions of film? Between sprockets on 35mm film and on the

edges of 120 film? This way you wouldn't have to ever bother with including

one in your scene and it would make things really easy when you are figuring

out how well you exposed?

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I <b><i>might</i></b> see this as useful on E6 and C41 film where a fairly standard

associated speed exists, but who is to say with black and white? Those who develop their

own generally use developers and timings to make their own speeds. If there were a standard

gradient it would have to be for a particular speed/developer/time combination (that

everyone would complain is wrong!). It would be useless for times when film is pushed or

pulled.

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Sounds attractive if you're doing "home E6"-no need to lash out for expensive control strips.

Of course , you'd need a densitometer and the process control manual.

Also need to consider if there's space on the rebate for it - its got to be measurable - and

also cost on film production.

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IMO, it would be useful even for self processed b&w. The "input" for the system is light, so a greyscale made with known amounts of light for each step would be meaningful regardless of processing, and would tell you actual film speed, gamma or c.i., and linearity. It would tell you if the film had aged or changed characteristics due to storage. It would even tell you if you mixed up the fixer and developer ;-) I'm in favor.
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Hi Jeffery

 

A few years ago I spoke at length to a Kodak techie about this very idea. The main problem would of course be the tremendous variation in exposure and processing usable with B&W film. There is also variation in production batch to batch, as well as aging effects- fog etc.

 

With all those variables, the Mfgrs would have a devil of a time dealing with complaints if the section at .10 were off by .02 or something like that. Also, the densitometers used would give different results- more complaints. A simple answer is for the user to photograph a standard exposure card at the beginning of each roll or session. Fred Picker would buy a year's worth of film, keep it in a freezer, do a test on one box, then keep all the variable constant for the year. I am told he was anal beyond beleif, but made many beautiful images.

 

As has been said, we have gotten along without it for 150 years or so, and I hardly think K or F or I or anyone else would start this at the sunset of the age of film.

 

The late Bob Mitchell came up with a scheme for colour where he photographed a standard grey card with each different light source and was able to establish filter packs in a few seconds for any colour light.

 

Cheers

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Try this on the first (or last) three frames of the film. Point the camera at a plain and evenly lit surface (I use the plain white wall in my kitchen). Expose one frame at the metered reading (this is mid-grey), then one frame at 4 stops over that reading and then one frame at four stops under the reading. Develop the film as per normal and use these frames as a reference. If ever you change developer or technique you can then use these three frames to see the effect.

 

If I change anything in my process I just shoot these three frames and then put them on the light-box next to my reference frames to see, in broad terms) what the effect has been.

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I think this is a good idea, and probably the only reason it hasn't been implemented is the practicality of it.

 

Imagine the speed that 35mm film zips out of the factory at. To get a consistent exposure at a rate of perhaps hundreds of frames a second wouldn't be easy, and if the exposure isn't consistent, then the whole idea falls down.

 

If you look at the current edge-numbering density, it varies quite a bit, sometimes even from one section to another of the same film. So, to tighten up the existing exposure tolerance would almost certainly increase the cost per film slightly, and since it would only benefit a tiny fraction of the customer base, the cost/benefit ratio is surely not favourable.

 

Those customers that need to, can buy process control strips or expose a test frame to a density wedge.

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Actually, a large nat'l photo studio chain I worked at in the mid-1980s did exactly what you propose. Now and then, we shot a gray card, which also had sitting data on it. Allowed lab techs to verify their processes.

 

But for a recreational shooter, shooting outdoors? Nah, I can't see the advantage. Studio is different, lighting is controlled.

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