Film Speed VS Usage & Reciprocity

[AlanKlein]

Box speed is the speed recommended by the manufacturer as shown on the box.

[Alan Marcus]

Film speed is determined by test methods as stipulated by the International Organization for Standardization (ISO) Geneva Switzerland. Prior to establishing international standards, the bureau of standards of individual countries set the rules thus different values were published for the same material. In the United States ASA (American Standards Association), In Great Brittan BSA, in Germany DIN (Normenausschuß der deutschen Industrie, In Russia GOST (Gosudarstvennyy Standart.

 

The testing method of the ISO is categorical and this value is published on a data sheet (box speed) supplied with the film. The published speed, though accurate, will vary based on actual conditions. We are talking about the age of the product, the chemicals and method used to develop the film etc. An important consideration is the calibration of the light measuring device used plus inaccuracies concerning actual aperture settings and shutter speeds.

 

 

In other words, the box speed (published speed) of film can be in error for a given camera and manner of developing and printing or displaying the pictures. Therefor it may be prudent for a photographer to run tests and perhaps modify the published ISO for a better fit for specific conditions.

 

Published ISO values are detailed for photographic film. The digital community has also adopted ISO approaches to categorize the sensitivity to light of electronic imaging seniors.

[Ricochetrider]

Thanks again, Alan for in depth information. I always wondered about the difference between ASA and ISO and you've explained that very well. Much appreciated.

[chuck909]

Just to be clear, reciprocity's meaning is not restricted to photography, nor is reciprocity failure.

 

Definition: the quality or state of being reciprocal : mutual dependence, action, or influence

 

Examples other than photography would be a trade deal between say the UK and Germany where goods of equal value are exchanged.

 

Reciprocity failure would be if you offered me a hamburger for my T-bone steak.

[SCL]

Another often overlooked factor in shooting film, knowing the ideal ISO/ASA and development technique, is whether ones' shutter speeds are within tolerance (typically 6-12% of manufacturer's stated speed). Older cameras periodically have shutter speed variances well out of tolerance, and if you are fastidious about exposure, you really need to know how much variance you have in your shutter speeds from stated values. Rarely is it more than 1 f/stop for a given speed...but, especially for positive (transparency) color film. it can definitely change the outcome. An old adage for color films to slightly enhance saturation is to slightly underexpose positive color films, and slightly overexpose negative color films. I've found this to be a good general rule of thumb for over 60 years of film shooting.

[rodeo_joe1]

Just to be clear, reciprocity's meaning is not restricted to photography, nor is reciprocity failure.

 

Definition: the quality or state of being reciprocal : mutual dependence, action, or influence

 

Examples other than photography would be a trade deal between say the UK and Germany where goods of equal value are exchanged.

 

Reciprocity failure would be if you offered me a hamburger for my T-bone steak.

 

- Well, yes, but then 'exposure', 'development', 'fixing', 'negative', 'enlargement', 'shutter', 'aperture', 'emulsion' and a host of other words we use, all have alternative meanings outside of photography. Rather, those words have been borrowed from common usage to describe processes or objects that we use in photography.

[chuck909]

- Well, yes, but then 'exposure', 'development', 'fixing', 'negative', 'enlargement', 'shutter', 'aperture', 'emulsion' and a host of other words we use, all have alternative meanings outside of photography. Rather, those words have been borrowed from common usage to describe processes or objects that we use in photography.

What about "humor"?

[rodeo_joe1]

What about "humor"?

 

- Yes, there's sense of humour failure too!

[Ricochetrider]

OK, still getting interesting, informative comments here... so clearly some of the shots with Portra 160 were underexposed, hence the grainy texture of the images, yes? The fix would be to allow more light particles to hit the film surface, yes? So wider aperture or longer exposure time or maybe a bit of both would be in order?

 

Let's say I have a 400 speed film vs the 160. (Basically the 2 film speeds I've shot so far) As I understand it, the 160 needs more light i.e. wider aperture and/or longer exposure time to fully sensitize the particles on the film surface? But the 400 film being a "faster" film requires less of both for optimum activation?

 

I have a roll of (expired) B&W film that has an ISO value of something like 25- really low. If I wanted to take that out into daylight, I'd want wide open aperture settings and slower shutter speeds? Would it be suitable for a long(er) exposure daylight shot?

 

(something else I've been wondering about- slower shutter speeds or longer exposures in broad daylight)

 

If I'm following along, (I think, I hope I am) the lower ISO film, if properly exposed, would result in a finer grained image?

 

Taking the comment about shutter speeds in old cameras into the mix, yes I am shooting with a manual, fully analog, vintage camera but having bought it from KEH, I assume it was CLA'd and therefore not off dramatically. Of course we all know what we open ourselves up to in assuming anything...

 

Having said that the old Zeiss lens does seem to have a special quality to it that even I notice compared to my modern lenses for my Olympus M4/3 camera?

[AJG]

You're right that lower ISO should correlate with more light exposure (either a wider f/stop opening or a slower shutter speed or a combination of those) and finer grain. Be aware that expired film may also be less sensitive now than when it was made, which is part of the reason for an expiration date on the box. As for older lenses, it is common for older lenses to render images with less contrast than the latest and greatest. As to which is better, that depends on what you want your images to look like.

[SCL]

You might benefit from the excellent book, "Light, Science & Magic" which covers many of the questions you have brought up as well as many you haven't asked yet.

[Alan Marcus]

It’s a common belief that old and expired film is less sensitive to light than fresh. I say, the inverse is more likely. Film is sensitive to light, heat, pressure, background radiation and chemical fumes. As time goes by, silver halides move towards and eventually arrive at a threshold whereby they became developable. In other words the fog level of film slowly elevates an in time spoil. Between these two periods, film become hyper sensitized. To explain, say a typical silver halide needs 1000 photon hits to become developable. Overtime, it receives 100 or more (from background radiation or comparable). Now this aged film only needs 900 photon hits during the camera exposure. Hyper sensitization is actually a valid method used to boost ISO. Fresh film is flashed to light or exposed to chemicals. Often the difference between a fast film and super-fast film is the fact that hyper sensitization techniques were used.

 

As to old lenses: The English optician Harold Taylor, in 1892 observed that old lenses transmitted 4 to 6% more light than new ones. He figured out why. Seems old lenses were blemished with soot. This was during the industrial revolution and the air was laden with smoke and soot from the coal fires that powered the steam engines and gave warmth. This coating of atmospheric pollution settled on lenses on the shelf and etched them. He discovered that this thin transparent coat somehow reduced surface reflections allowing more light to transverse the lens.

 

Taylor experimented and found a way to artificially bloom (age) lenses. This truly was an important discovery because new lenses suffer a 4 to 6% loss in light due to light being reflected from their polished (mirror like) surfaces. Now lenses used in cameras and telescopes are complex systems with many lens elements sandwiched together. Thus multi-lens element systems can suffer a loss of 40 – 50%.

 

This discovery and remedy is important as modern lenses often use many elements and groups. Losing 4 to 6% at each junction translates to quite a high loss. Most loss is from internal junctions (glass to air and glass to glass) within the barrel. Each internal reflection caused light rays to go astray and many misdirected rays bathed the film/chip with light scatter called flare. Flare is devastating; it degrades the image by reducing contrast. Gross reflections cause glare spots.

[chuck909]

OK, still getting interesting, informative comments here... so clearly some of the shots with Portra 160 were underexposed, hence the grainy texture of the images, yes? The fix would be to allow more light particles to hit the film surface, yes? So wider aperture or longer exposure time or maybe a bit of both would be in order?

 

 

I think you're making this way more complicated than it really is. General rules:

 

The slower the film, the finer the grain

 

Even a fresh from the factory high quality camera can have shutter speeds off by 10% and still be considered within tolerances.

 

Typical exposures bright sunlight:

 

ISO 25 - 1/125th @ f8 - unless you use neutral density filters or shoot at 1/1000th or faster you will not be shooting wide open (depending on the speed of your lens)

 

ISO 160 - 1/125th @ f16

 

ISO 400 - 1/500th @ f11

 

Do NOT worry about reciprocity unless you get into very long exposures, say 10 seconds or more.

Chances are you'll never run into that kind of situation. And if you do, you're going to bracket your exposures anyway.

 

I don't know where you live, but you might want to find out if there are any camera clubs in your area. Go out with someone who knows the ropes and you'll pick all of this up quickly. Too bad, but gone are the days when a camera store with sales people who knew cameras were on every other block.

 

Normally I very slightly over expose print film, but you'll have to judge for yourself if that's right for you.

Edited January 7, 2019 by chuck909

[Ricochetrider]

Chuck, thanks. I do tend to over complicate things... There is/are local camera clubs around here, most everyone shoots digital cameras tho, I'm not sure any of them shoot film although I can still learn from this folks, without doubt. Also there is a local camera store and the owner whom I've gotten to know over the past few years, is very knowledgeable and has shot just about every kind of camera imaginable.

 

Some of my questions may actually be above my capabilities but my brain still finds them and so I ask.

[chuck909]

Chuck, thanks. I do tend to over complicate things... There is/are local camera clubs around here, most everyone shoots digital cameras tho, I'm not sure any of them shoot film although I can still learn from this folks, without doubt. Also there is a local camera store and the owner whom I've gotten to know over the past few years, is very knowledgeable and has shot just about every kind of camera imaginable.

Some of my questions may actually be above my capabilities but my brain still finds them and so I ask.

 

Even if they all shoot digital, unless everyone in the club is under 35 years old (a guess), there will be those who have shot film and maybe still do. The local camera club here is mostly digital, but there are a few hold-out.

 

Do you have an instruction manual for your camera? (what make is it - or did you post that already) And if you DO ever need to figure out reciprocity, all of the film manufactures have guides for just that.

 

Most of my experience dealing with reciprocity has involved photographing fossil sea shell the size of a large pin head using a bellows and a 20mm macro lens for my paleontologist brother. Bracketing was a matter of course.

[Ricochetrider]

Hi Chuck, My camera is a Hasselblad 500cm. I was just thinking I should say this, I doubt I've mentioned this in this thread. It has no setting for ISO/film speed and a limited range of aperture and speeds.

 

This did begin as a query into reciprocity to some degree, but is also a ISO/film speed/settings discussion. I began by trying to understand why some my images were grainy, and we've established they were underexposed.

[chuck909]

If no one had directed you here before, go to: Hasselbald 500c instruction manual, user manual, free PFD camera manuals

 

(500C v 500CM - no practical difference)

 

What do you have for a light meter? The standard 500CM does not come with one though one can be added on, either as a replacement for the winding knob or as a TTL meter.

 

As for limited speeds and aperture choices, they were standard for that kind of camera. The Hasselblad was never intended as a camera for high speed (sports) work. Its forte was/is fashion, weddings, portraiture, etc.

[rodeo_joe1]

Might I suggest carrying your digital camera with you to get immediate feedback over what happens when you change aperture, shutter speed and ISO rating. You can also use the digital camera as an exposure meter.

 

Put the digital camera into 'M' - manual - mode, and turn off Auto ISO so that you have to set everything manually, just like with film. You should therefore be able to duplicate the settings on your 'blad and see almost exactly what the film result will look like.

 

Film is an awful medium to learn with, simply because of the delay between pressing the shutter and seeing the result. You get no feedback or feel for what effect changing exposure variables has.

 

The shutter speed alters the amount of time captured, and any subject or camera movement will cause an increasing amount of blur as the shutter speed gets longer.

 

The aperture affects both depth-of-field - the amount of front-to-back sharpness - and the amount of light let in by the lens.

 

You can experiment with these variables at no cost and to your heart's content using digital, and hence accelerate the learning process.

 

There's also no doubt about what caused any fault or change in the result, such as you might get with film. 'Was it me, the processing or the scanning?' is no longer in question. If you get it wrong in digital - it's you!

Edited January 7, 2019 by rodeo_joe|1

[chuck909]

Joe and I will disagree as to whether film is a awful medium to learn with. Or do we agree as I prefer the less often used definition of "awful" as in inspiring awe.

 

And no, I won't argue the point. It's been argued more than enough

[rodeo_joe1]

C'mon Chuck, admit it. You're just jealous, because when I, and I suspect you, were learning the craft we were stuck with film and it took years. Using digital can cut that learning curve down to months, or even weeks with the right guidance and tuition.

 

Being able to simply and immediately see the result of, say, changing the shutter speed and getting or eliminating motion blur is priceless.

 

Does anyone really want to hold a beginner back to learn at film's snail pace?

[chuck909]

"stuck" with film? FYI, I started out in photography teaching Mathew Brady how to coat wet plates, so when Mr. Eastman came along, I could hardly contain myself. Talk about making photography easy.

[chuck909]

I will concede that in the point and shoot mode, yes, digital is pretty easy. My challenge to you is to pick up your digital camera and explain what EVERY function and feature is for and how it works - without referring to that 450 page manual that so many tote around with them. Hmm, explain what a histogram is all about to a beginner? How is that easier than explaining that a faster shutter speed can freeze action. If I can teach a little old lady from North Dakota how to use a 35mm SLR in under an hour (see a previous post of mine), film can't be all that difficult.

 

And no, I won't say that film is as good as digital. That's not at all what I'm talking about. But I will say that it is not as difficult to master as you would have a beginner believe.

 

You have all these poor beginners shaking in their boots.

[rodeo_joe1]

You have all these poor beginners shaking in their boots.

 

- No. I'll have them seeing and understanding exactly what the effect of aperture, shutter speed and ISO are. And far quicker than if they had to wait for film to be (likely badly) processed.

 

No need to even glance at a histogram, change metering or AF mode, or use any of the other unnecessary refinements that a digital camera offers.

 

Nobody is talking about point 'n' shoot mode. But about understanding manual controls, by seeing and doing. And at no cost, since the OP already owns a digital camera.

 

Leaving film use until the basics of exposure are fully grasped.

 

What's so bad about that?

[chuck909]

- No. I'll have them seeing and understanding exactly what the effect of aperture, shutter speed and ISO are. And far quicker than if they had to wait for film to be (likely badly) processed.

 

No need to even glance at a histogram, change metering or AF mode, or use any of the other unnecessary refinements that a digital camera offers.

 

Nobody is talking about point 'n' shoot mode. But about understanding manual controls, by seeing and doing. And at no cost, since the OP already owns a digital camera.

 

Leaving film use until the basics of exposure are fully grasped.

 

What's so bad about that?

So, if Mr. X wants to get into photography and wants to use film, he should go out and buy a digital first so he can know what he doing?

Let's just agree to disagree

[rodeo_joe1]

The OP has already said he has a 4/3 digital camera.

 

What part of that isn't understandable Chuck?

 

And Mr X hasn't posted here yet!