Need some help with the Zone System

[What About Bob]

Many moons ago, before graduating from Hallmark, I did a few assignments that involved the use of preexposure to the film before making the shot. I used a gray card for the preexposure, stopped down three to four stops for a Zone 2 or Zone 1 preexposure of the card then exposed the scene normally. This was easy with the Hasselblad: preexpose then remove the magazine, wind her up and then put the magazine back on and then make the shot. With 35mm you needed to hold in the rewind button while advancing the lever to stay on the frame.

From my recollection this preexposure technique worked decently but there were limitations. For example if you had a great amount of shadow area that didn’t contain much detail then the result would be on the drab side. By going too far with the preexposure the results could be very bleak. A little bit goes a long way and you could compensate later on by using a step higher in contrast filtering in printing to bring the shadows back down.

Also when making the preexosure with the gray card or some other object with a gray tone it is important to rack the lens out of focus so that you don’t record the texture of the object. Maybe in certain situations having added texture could lend to a neat effect with some subjects.

The good old days of experimenting.

 

[Augustus Caesar]

As I was saying, the ISO standard ovwer-rates B&W films:

From:

First Time Developing Tri-X 400. Too much grain? - PentaxForums.com

Hi all, Yesterday I developed my first roll of Tri-X 400 using Ilford ID-11 developer, diluted to 1+1. I followed the suggested time of 11 minutes,

www.pentaxforums.com

"This is only somewhat related to your question, but long ago I was the member of a pretty active camera club in Upstate New York. One evening they had a representative from Kodak in to do a talk about photography in general as well as discuss Kodak films. He was also a professional photographer himself. He said that even though Tri-X tests out at ISO 400 using the ISO test standard, you can get better tonal grading (less contrast-y) and overall a better look if you expose it as ISO 200 and pull-process it. I started doing this and do think I got better looking results. On the plus side, it also results in a finer grain. <-- There I made it relevant to your question.

If you do your own film processing, it's easy to pull process - you just need less development time. I don't recall, it's been so long, but I think the Tri-X insert instructions provided push or pull processing instructions. If you send the film out, you'll need to make sure your lab is able to do this.

In general, however, the older black and white films like Plus-X and Tri-X will produce more grain than the more modern T-Max films. Kodak developed the T-grain chemistry specifically to improve the grain in their color films, then carried it over to their black and white films.

It's been a long time since I've developed any film, but as I recall the developer chemical you use can also effect grain and other characteristics. The two developers in vogue at the time I was doing this were Microdol-X and D-76. I learned to use Microdol-X as that was supplied in our high school darkroom for our camera club. Microdol-X was known for producing finer grain, but could result in a slight halo effect in the vicinity of high contrast edges in the image. D-76 was a faster developer, but did result in more grain. There was another developer that I can't recall the name of that produced better grain than D-76, but didn't create the halo effect. I don't know how the Ilford developers compare, I've never used them, but this is another avenue you can explore for achieving finer grain."

---

Read more at: https://www.pentaxforums.com/forums...g-tri-x-400-too-much-grain.html#ixzz8KydMhJsj

 

[Vaughn]

I used Microdol-X back in the early days, too, for 120 film (70s). But at 1:3, which I thought at the time would give me nice grain that was not mellowed out too much due to diluting the silver solvent and would maintain some of the sharpness. Using a lot of Panatomic-X. It was a nice combo, but I can't say I did any testing of different combos beyond D-76.

 

[Doremus Scudder]

When will people realize that the ISO standard is predicated on a specific contrast gradient achieved using a particular exposure and development regime, which may not be to everyone's liking. It often also doesn't match the exposure (think metering here too) and development possibilities available to most photographers.

If you don't like "box speed" or the contrast achieved with recommended development times (I don't either), then don't use them. Still, ISO gives a standard basis of comparison.

Grousing that using box speed and recommended development doesn't give you the desired results is pointless; the standard isn't about to change any time soon. Just make your own modifications/adjustments.

Once you've figured out one film, you can apply those adjustments to every other film as a starting point. If you like rating one film at half of box speed and then developing it 20% less than recommended, then do that with other films as well. Just because that works for you, doesn't mean that the standard should be amended to match your preferences.

Best,

Doremus

 

[Augustus Caesar]

When will people realize that the ISO standard is predicated on a specific contrast gradient achieved using a particular exposure and development regime, which may not be to everyone's liking. It often also doesn't match the exposure (think metering here too) and development possibilities available to most photographers.

If you don't like "box speed" or the contrast achieved with recommended development times (I don't either), then don't use them. Still, ISO gives a standard basis of comparison.

Grousing that using box speed and recommended development doesn't give you the desired results is pointless; the standard isn't about to change any time soon. Just make your own modifications/adjustments.

Once you've figured out one film, you can apply those adjustments to every other film as a starting point. If you like rating one film at half of box speed and then developing it 20% less than recommended, then do that with other films as well. Just because that works for you, doesn't mean that the standard should be amended to match your preferences.

Best,

Doremus

I have explained why the ASA speed measurement was changed, and why the change was unnecessary (or ill-advised) for people using 35mm focal-plane shutter cameras. The popularity of leaf-shutter lens cameras was waning just at the very time the standard was changed. For those using Contaflexes, and other 35mm leaf-shutter cameras (remember the Argus C3?), the new standard was beneficial. The situation was that by the mid-fifties faster films had appeared, and this forced users of the older cameras to use smaller apertures than they had before. As I have explained, this allows more exposure with leaf shutters than focal plane shutters give. Also, these leaf-shutter cameras rarely had shutters that went above 1/300s.

As I have repeatedly said, this happened right when cheaper Japanese SLRs were being introduced. Pentax, Miranda, Topcon, Nikon, Minolta, and others led the charge.

So, the revised ASA speeds did what they were intended to do, for users of cameras that were gradually being replaced by SLR cameras that did not give as much exposure at small apertures. 1/300 sec @ F/16 on a Nikon with an FP shutter will give less exposure than 1/300 sec @ F/16 on a Contaflex with a leaf shutter. Thus, the revised (increased) ASA speeds were not needed by FP shutter users, and are not needed today either, unless the photographer is using a leaf-shutter camera (Hasselblad, view camera) AND small apertures.

This one tops out at 1/200 sec:

 

[koraks]

1/300 sec @ F/16 on a Nikon with an FP shutter will give less exposure than 1/300 sec @ F/16 on a Contaflex with a leaf shutter.

Interesting.

A focal plane shutter will expose the film at short exposure times by moving an open slit across the film plane (vertically or horizontally). Since the shutter is close to the focal plane (what's in a name), there's virtually no intermediate zone between open and closed shutter. Each spot on the film/sensor virtually instantaneously 'sees' light as the slit arrives and then goes dark again once the slit leaves that spot. The light flux intensity vs. time plot would look something like this:

For a slow speed, the above plot will also be true for a leaf shutter. Take e.g. a 1 second exposure: the opening of the shutter leaves is virtually instantaneous in relation to the long overall duration of the exposure, and the process of opening and closing of the leaves won't affect the exposure much. It's different for high speeds, where a leaf shutter will start to show this kind of behavior:

Keep in mind that what matters is how much actual exposure each bit of the film/sensor receives: the green area underneath the plot.

Now, in your post, you seem to make an assumption of the shutter speed being the time the shutter starts to open and finishes closing. I don't think that's accurate, because shutter manufacturers have been aware of the above issue for over a century, and they figured out long ago that in order to maintain reciprocity between exposures (i.e. a 1/500 exposure is really half as much as a 1/250, which in turn is half as much as 1/125, etc.), they would have to take into account the opening and closing of the aperture blades. Consider this:

The actual shutter speed for a fast time on a leaf shutter will not be T2a-T1a, but rather T2b-T1b. Of course, there's the practical challenge of actually making getting this exactly right in a small mechanical device that should function reliably for decades under adverse conditions, but decades and decades of innovation in mechanical engineering have resulted in rather reliable mechanical leaf shutters that do reasonably well up to reasonably fast speeds.

Now, the problem with the aperture is that if the aperture is extremely close to the leaf shutter (it's evidently never close to a focal plane shutter), a very small aperture opening (large f/number) would block a large part of the light falling through the open shutter. This would result in small apertures (large f/numbers) giving relatively more exposure (not less, as you suggested) at such apertures compared to shooting wide open. However, in a practical design, the aperture is always a little bit offset from the shutter (which optically is a compromise of course) - and even a little bit of distance between a small aperture and an open shutter will still allow a whole lot of light to pass through and reach the film/sensor.

So, to the extent your argument has theoretical merit, it's in the opposite way of what you suggested.

In reality, I think the most important development around the time of the ISO revision standard is exactly what you mentioned: the introduction of new camera and shutter systems with far more accurate and consistent shutter speeds (or rather: effective exposure), across the shutter speed range and over the equipment's service life. This meant that a little less leeway was needed in allowing for natural variations in equipment (which effectively reduced, and quite dramatically at that), allowing for the same film to be rated a little higher because it was easier/safer to balance a little closer to the exact exposure instead of having to build in a massive fudge-factor to allow for Ansel's well-maintained leaf shutters used at half a second all the time vs. aunt Edna's Medalist shutter whizzing away at a sluggish (?) or rapid (??) 1/50 during family picknicks.

This, and there were changes to basic assumptions underlying sensitometry such as a change from 2700K to 4700K as a sensitometric starting point, but these were also aimed at improving consistency between different types of equipment and workflows rather than accounting for some inherent problem with leaf shutters. Btw, if they were so problematic, I'd have expected Hasselblad etc. to have left them behind long ago. Apparently they didn't see a necessity for it.

 

[Keith Tapscott.]

In the Kodak Films For Black And White Photography book (1958 7th Edition) it gives speed ratings of 80 ASA for both Verichrome Pan and Plus-X pan films respectively. These later became 125 ASA.
Oddly, the development times in D76 are much longer for the 80 ASA speed ratings than those for the later 125 ASA ratings.

 

[Stephen Benskin]

I have explained why the ASA speed measurement was changed, and why the change was unnecessary (or ill-advised) for people using 35mm focal-plane shutter cameras.

That's not the reason for the change in the standard. You picked a paragraph out of the paper and used it to represent the entire paper. It doesn't. It was about one variable which adds to the possible range of exposure variability. Remove it as a variable and you still have the 2.4x safety factor. Include it and you have exposure deviation from no additional exposure to some additional exposure above the safety factor. It’s not the cause of the safety factor nor the reason for the adjustment. If it were, there should have been corresponding changes to the color negative or color reversal standards and not just to the black and white standard. The reason for the change is right in the title Safety Factors in Camera Exposure.

 

[MattKing]

Standards that support the usage of the vast majority of users - both individual and industry - should not be changed because a tiny minority of people prefer to use different approaches in order to obtain specialized results.
Understand the standards, and then use any specialized approach you wish to obtain any different results you wish.
This thread reminds me a bit of Bruce Barnbaum - whose prints are wonderful, but whose explanations about why and how things happen are more mystical then methodical.

 

[Augustus Caesar]

Standards that support the usage of the vast majority of users - both individual and industry - should not be changed because a tiny minority of people prefer to use different approaches in order to obtain specialized results.
Understand the standards, and then use any specialized approach you wish to obtain any different results you wish.
This thread reminds me a bit of Bruce Barnbaum - whose prints are wonderful, but whose explanations about why and how things happen are more mystical then methodical.

The vast majority of users of B&W negative materials, if they follow ISO speeds and meter carefully, are slightly underexposing their film, if they are using FP shutter equipment. Go ahead and test, and see what you come up with. Use an incident meter.

 

[Augustus Caesar]

That's not the reason for the change in the standard. You picked a paragraph out of the paper and used it to represent the entire paper. It doesn't. It was about one variable which adds to the possible range of exposure variability. Remove it as a variable and you still have the 2.4x safety factor. Include it and you have exposure deviation from no additional exposure to some additional exposure above the safety factor. It’s not the cause of the safety factor nor the reason for the adjustment. If it were, there should have been corresponding changes to the color negative or color reversal standards and not just to the black and white standard. The reason for the change is right in the title Safety Factors in Camera Exposure.

The safety factor for what? How is exposure to be calculated to begin with? Do you remember those leaflets that used to come with Kodak film, which gave suggested exposures for different lighting conditions? You'll note that they do not mention shutter types.

 

[Bill Burk]

Many moons ago, before graduating from Hallmark

Kansas City? Greeting cards? My sister's best friend "Wendy" worked there.

 

[Bill Burk]

@koraks The bell curve of exposure with a leaf shutter is well known and can explain why digital measurements of shutter speed are less reliable with a leaf shutter at its higher speeds.

But the real quandary is that at smaller apertures, the shutter which is trying to open and close fully in 1/300 second... is going to seem "fully open" instantaneously at f/16 (and then waits til the end to shut immediately). While at f/3.8 there is a bell curve exposure.

Nothing I know can really measure this except to say wide open a high speed leaf will be nominal and at small apertures the leaf shutter will nominally provide a greater exposure due to lack of bell curve.

I would do an exposure test in camera of a gray card and measure with densitometer. But the test series involves changing the light intensity over several stops. This isn't always practical with continuous light sources. Now you have to be careful not to change the color temperature of the light as you test. (So incandescent lights on a dimmer are right out).

 

[koraks]

But the real quandary is that at smaller apertures, the shutter which is trying to open and close fully in 1/300 second... is going to seem "fully open" instantaneously at f/16 (and then waits til the end to shut immediately). While at f/3.8 there is a bell curve exposure.

Yes, that's why I said:

Now, the problem with the aperture is that if the aperture is extremely close to the leaf shutter (it's evidently never close to a focal plane shutter), a very small aperture opening (large f/number) would block a large part of the light falling through the open shutter. This would result in small apertures (large f/numbers) giving relatively more exposure (not less, as you suggested) at such apertures compared to shooting wide open.

And the rest of it. It's directly below the bell curve plot you commented on.

 

[Bill Burk]

I know we’re both saying the same thing small aperture gets greater integrated exposure. But the words of our explanations are not clear.

You can’t accurately measure the high shutter speeds of a leaf shutter without characterizing the chosen f/stop(s) for the test(s). So I’ll try again to say the same thing you’re saying.

The smallest aperture would have this curve. It seems to open immediately and seems to close immediately. It gets full exposure the full time of the travel.

The widest aperture would have this curve. It opens relatively slowly and closes relatively slowly but in the same travel time. It doesn’t get as much exposure.

 

[BrianShaw]

We should have a sticky thread: Need some help with the shutter efficiency.

 

[Stephen Benskin]

The safety factor for what? How is exposure to be calculated to begin with? Do you remember those leaflets that used to come with Kodak film, which gave suggested exposures for different lighting conditions? You'll note that they do not mention shutter types.

View attachment 355882

The shutter argument, while an important topic, isn't determinative when it comes to film speed determination. I forgot to mention, mechanical variables wouldn't be addressed by changing the film speed standard but by adjusting how exposure is determined like changing the exposure meter standard. Please read the paper carefully, and don't dismiss a seminal paper out of hand.

 

[Bill Burk]

The paper can be accessed here.

Index of /benskin/content

It’s fine to have a soapbox discussion all to the effect “how can I trust my film speed when there are so many variables involved in the tone reproduction process. Everything is chock full of variables: light/film/shutter/aperture/development/printing

Amazing thing is it works at all. Nice thing is you can mess up a lot (think 30%) and still get outstanding results. But you have to nail it all to get it perfect. After a while you come up with your own idea of what perfect means to you. Then other people see what you do, like it, and want to hear stories how you did it.

 

[Vaughn]

Shutter speed...most of my exposures are greater than one second. On top of Sentinel Dome with the 5x7 during a family reunion a couple years ago, I counted out the seconds out loud so folks would know how long to hold still...one anseladams, two anseladams, three anseladams...
When it came time for me to be in a photo, a relative worked the shutter for a multi-second exposure. Unfortunately the neg got a bit too much exposure as the whole crowd on top of the dome joined in with the counting of: one anseladams, two anseladams...but at lot slower rate...by 50% or more... Loved it!

 

[GregY]

Shutter speed...most of my exposures are greater than one second. On top of Sentinel Dome with the 5x7 during a family reunion a couple years ago, I counted out the seconds out loud so folks would know how long to hold still...one anseladams, two anseladams, three anseladams...
When it came time for me to be in a photo, a relative worked the shutter for a multi-second exposure. Unfortunately the neg got a bit too much exposure as the whole crowd on top of the dome joined in with the counting of: one anseladams, two anseladams...but at lot slower rate...by 50% or more... Loved it!

Vaughn that is one beautiful & memorable photo!

 

[What About Bob]

Kansas City? Greeting cards? My sister's best friend "Wendy" worked there.

Hallmark Institute of Photography. It was located in Turners Falls, Massachusetts. Sadly the school is no more. No relation with greeting cards.

 

[Alan Edward Klein]

Shutter speed...most of my exposures are greater than one second. On top of Sentinel Dome with the 5x7 during a family reunion a couple years ago, I counted out the seconds out loud so folks would know how long to hold still...one anseladams, two anseladams, three anseladams...
When it came time for me to be in a photo, a relative worked the shutter for a multi-second exposure. Unfortunately the neg got a bit too much exposure as the whole crowd on top of the dome joined in with the counting of: one anseladams, two anseladams...but at lot slower rate...by 50% or more... Loved it!

I like that shot.

 

[Augustus Caesar]

The shutter argument, while an important topic, isn't determinative when it comes to film speed determination. I forgot to mention, mechanical variables wouldn't be addressed by changing the film speed standard but by adjusting how exposure is determined like changing the exposure meter standard. Please read the paper carefully, and don't dismiss a seminal paper out of hand.

I am hardly dismissing the paper. In fact, I find it most gratifying, since it mentions the small-aperture leaf-shutter issue. Films were getting much faster by the mid-1950s (Tri-X came out in 1954), and the kinds of cameras owned by most amateurs were simply incapable of handling these fast films in a way that allowed larger apertures to be used in bright condirions. The users were forced to use the smallest apertures and highest shutter speeds, which in many cases did not exceed 1/200s. Given that photo-finishing practices at that time were generally suited for contact prints from larger negatives, 35mm films developed by these standards were likely over-developed. I have seen the negatives from films that my father took on his honeymoon in 1948 (with an Argus C3), and they seem pretty dense.