Help me understand one thing re. b&w and exposure error

[kennylovrin]

Hey

So I try to read as much as I can now that I've just started out with B&W photography. And one thing I keep coming across is people mentioning how much latitude and room for exposure error there is in b&w films.

So now I need help with clarifying one thing;

I understand what it means to have much room for exposure error, but let's say I overexpose one frame a few stops, then I underexpose another frame a few stops and so on. This "room for error" is that referring to that "it will sort it self out a bit during development" or is it rather referring to "if you overexposed you can adjust development time to save it"?

Because in the case of the latter, in practice it really means that there is no room for error, because you have to know that you exposed wrong so you can adjust development. And if you know you did it, it's not really an "error" is it because it would have to be done to every frame consistently for you to be able to save it with adjusted dev time?

I don't know if this is a stupid question, but saying "there is a lot of room for error" is like saying "just go out and wing it", and I'm not sure sure that is actually what is being said? 🙂

Thanks,
Kenny

 

[FrankS]

Exposure latitude for black and white film is about minus one to plus five stops. Within that range, you will be able to obtain a useable image when printing in the darkroom. With scanning, plus five stops may be a bit too much as the negative will be quite dense.

 

[Nomad Z]

My understanding is that latitude is how much the exposure can be out for a given development process and still yield a usable neg. It also seems to me that the supposed latitude of a particular film depends on the brightness range of the subject. If B&W has -1 +5 stops of latitude, how much latitude does it have if the brightness range of the subject increases by 6 stops? (None, surely.)

 

[kennylovrin]

Exposure latitude for black and white film is about minus one to plus five stops. Within that range, you will be able to obtain a useable image when printing in the darkroom. With scanning, plus five stops may be a bit too much as the negative will be quite dense.

Ok, so I do in fact have room for exposure errors of different severity within one roll if I understand you correctly. The roll might come out a bit funny I imagine with some frames very dark and others very light, but still usable then?

Your point about darkroom printing vs scanners is interesting though. My understanding is that the strength of the scanner light is constant, so if I have a very light flat negative and change the levels during scan I'm actually doing the same thing as scanning it flat and white and post processing it for contrast? What I'm thinking is that the dynamic range is directly related to what the scanner can produce, no matter how I adjust the scan in the scanner software. That would differ as opposed to darkroom printing where you actually can apply more or less light. Even if I have a scanner that can shine through really dense negatives, it might not be able to resolve the details in the light parts with the amount of light needed for the denser parts. I'm thinking of it as a digital camera here, but I'm not sure if that is right or wrong.

I might be going off trail a bit here, not sure it is making any sense.. Kind of thinking out loud. (The reason I'm thinking about this is because I'm unhappy with my scanner, as seen in another thread. Have another one coming though to try hopefully tomorrow 😉)

 

[Rangefinderfreak]

The B&W negative image has many variables when you are aiming to a certain "look" Slow films behave different from fast (400 asa or more) development is dependent of temperature, strenght of the developer , time of development and agitation. They all affect the negative, how dense or flat/ contrasty it is. There is no such a thing as "perfect negative" It is all dependent on your style and taste for the final image.
Now it is considerably easier to get a satisfactory image, because of scanners, photoshop and good quality digital printers. The "wet process" is considered by many to be still superior, but takes a lot of experimenting and practice to come up with a satisfactory print. I personally prefer Film and scanned quite flat, like "RAW" in digital and then work towards a satisfying print with curves, layers etc in photoshop.

 

[Fawley]

Exposure latitude, which I think of as the extent to which you can over or under expose, depends very much on the brightness range of the subject. If you have a very small brightness range, as in a street scape on a cloudy day, you have a lot of latitude to produce a negative that will still have all the information. The neg might be thin or thick but the information will be there. But if you have a large brightness range, something with deep shadows and bright highlights, your exposure has to be fairly accurate, otherwise you will either underexpose the shadows (and no amount of overdevelopment will produce negative density where there is no exposure) or else you will overexpose and get blown highlights. In this case whether it is better to over or underexpose depends on what you want to show in the picture.

 

[ColSebastianMoran]

Exposure latitude for black and white film is about minus one to plus five stops. Within that range, you will be able to obtain a useable image when printing in the darkroom. With scanning, plus five stops may be a bit too much as the negative will be quite dense.

Frank, of course, is correct, but notice that he said "usable" image, not "optimal" image.

You need correct exposure and development to get an optimal image.

When people talk about latitude, they are talking about how rapidly image quality suffers with wrong exposure. B&W film is less sensitive to exposure errors. Color negative film would be next. With color slide film, your image quality is the most affected by exposure errors.

Again, it's still better to have the correct exposure.

 

[kennylovrin]

How do you guys normally meter with b&w by the way, if you use a center weighted meter let's say. Another pretty strange question maybe, but it's another of those things that aren't obvious to me as somewhat of a beginner.

With the M6 I just bought I've had to work with center weighed metering as opposed to the digital cameras that I've used that have matrix metering etc. That being said, I'm not always too fond of matrix metering as it sometimes have tendencies to adjust for things that doesn't really always makes sense.

So, I'm totally up for this center weighted metering, nothing against it. But is the M6 metering generally a bit more narrow than "normal" center weighted if there is such a thing? It seems to me it is fairly sensitive for even small motions of the metering area.

Anyway, so given you use something like the M6, do you then find the darkest shadow you want to retain detail in and underexpose for that, or you aim for something closer to medium gray and expose as the meter wants? With digital I sometimes used to resort to metering the highlights and going over to get it as close as I wanted to white, but I know that doesn't apply to negative film.

Most of the time so far I've ended up just metering on the subject and kind of trying to figure out how far off medium gray it might be on either side. I haven't found it too easy so far as colors can sometimes throw you off and actually render a lot brighter or darker in gray scale than they look in color.

What I'm asking here is more of what is the most common way for you guys. Theoretically I understand it, but I'm not sure how most people apply it in practice with a camera with a built in meter. I don't usually find myself in situations where I have time to meter all over the place and do a calculated exposure, if that makes sense.

 

[Vics]

Latitude has to do with how many stops of tone one can encompass in one image. Ansel Adams called them "zones". It means that if you measure the darkest spot in your frame in which you want "some" detail (black with visible threads, e.g.) and set that exposure on your camerra, then stop down by three stops, you are "placing" that tone in zone 2. Then you measure the brightes highlight in which you want detail (white-painted wall with visible wood grain) and open up three stops to place it in zone 8. Those two operations SHOULD get you the same setting on the camera. If they don't you must adjustg development time in order to expand or contract contrast so that you can print in number two paper.All of this lastitude business has been, over the years, misconstrued by many to mean that one can cover his ass with the film's tonal range. It's not really so. An under exposed neg prints muddy and looks under-exposed. Tri-X has lots of tonal range, but very little tolerance for under-exposure. Over-exposure gives you blown highlights and magnifies grain in skin tones and skies.
In 35mm film, I expose for the highlights (as above) and let the chips fall where they may with normal development. I hope this made sense to you.

 

[Vics]

When things are moving fast, I just check with my incident meter if the light seems to have changed. In more stable circumstances, I meter the shadow and stop down three stops from that reading. If the shadow reads 1/250 at 2.8, I shoot at 1/250 at 8.0.

 

[charjohncarter]

The old rule: if you are going to error then overexpose film and if you are going to error on development; under develop.

 

[Fawley]

Re your question on metering. I am useing older rangefinders and hand held reflective meters more and more. If I have time, I meter the shadows and then check the highlights. But often for street scenes there is no time and for this type of photography I use a faster film with a lot of latitude. On scenes with average lighting and I want both shadows and highlights, I find that the sunny 16 rule almost always works. But when I use Ilford Pan F on a bright day (very little exposure latitude and no room for under exposure), I meter with a spot meter and work out the exposure in each "zone" very carefully.

 

[TXForester]

Ok, so I do in fact have room for exposure errors of different severity within one roll if I understand you correctly.

You do up to a point. However you have to make a choice. 1) Develop normally and hope your underexposed and overexposed frames fall within a usable range. 2) Or, push or pull, to save some of the frames, hope that the "normally" exposed frames where not hurt by the development, and be content that frames on the other end of the scale will most likely be lost. With either choice you are compromising. You can't have it all, when exposures all over the map.

 

[Richard G]

How do you guys normally meter with b&w by the way, if you use a center weighted meter let's say. Another pretty strange question maybe, but it's another of those things that aren't obvious to me as somewhat of a beginner.

With the M6 I just bought I've had to work with center weighed metering as opposed to the digital cameras that I've used that have matrix metering etc. That being said, I'm not always too fond of matrix metering as it sometimes have tendencies to adjust for things that doesn't really always makes sense.

So, I'm totally up for this center weighted metering, nothing against it. But is the M6 metering generally a bit more narrow than "normal" center weighted if there is such a thing? It seems to me it is fairly sensitive for even small motions of the metering area.

Anyway, so given you use something like the M6, do you then find the darkest shadow you want to retain detail in and underexpose for that, or you aim for something closer to medium gray and expose as the meter wants? With digital I sometimes used to resort to metering the highlights and going over to get it as close as I wanted to white, but I know that doesn't apply to negative film.

Most of the time so far I've ended up just metering on the subject and kind of trying to figure out how far off medium gray it might be on either side. I haven't found it too easy so far as colors can sometimes throw you off and actually render a lot brighter or darker in gray scale than they look in color.

What I'm asking here is more of what is the most common way for you guys. Theoretically I understand it, but I'm not sure how most people apply it in practice with a camera with a built in meter. I don't usually find myself in situations where I have time to meter all over the place and do a calculated exposure, if that makes sense.

I think you've asked two good questions in one post. On the second question I would start by saying just trust the M6 meter. After all, the M7 supposedly allows you to snap away in AE mode, and I think it has the same meter. I use a hand held meter with my M2 and often check the M6 metering and often do a quasi incident reading with the M6, metering off my hand etc etc. Very often, as in nearly always, if I just ignore the specifics and balance the two red LEDs I get a good exposure. The times when I really need to over-ride the M6 meter are when it is obvious that the scene is uniformly dark or bright, and I will manually compensate, or ignore the meter altogether and shoot with sunny 16. That meter in the M6 is the single greatest justification for having that particular camera, and it is a very good meter.

 

[Sanders McNew]

No, don't wing it. The "latitude" is all in the direction of overexposure. Underexpose even a stop, and you lose a lot of detail. When in doubt, slow your shutter and open your aperture.

 

[FrankS]

Don't just wing it, but don't get obsessive over metering either.

 

[ColSebastianMoran]

You could apply zone system thinking... Look at the shadow areas; add fill light or make sure you have enough exposure so that you don't lose detail in the shadows.

Easy to say. Doing this in practice might border on obsessive, but it's part of the secret of really good B&W negatives.

For digital shooters who might be reading this: with digital and slide film, it's the other way around, make sure you don't overexpose the highlights.

 

[kennylovrin]

Yeah, I'm trying to think about the shadows instead. It's tricky though, I have a tendency to look at the subject instead and try to evaluate it's brightness relative to medium gray. I just need to try to stop doing that. 🙂

 

[ColSebastianMoran]

I have a tendency to look at the subject instead and try to evaluate it's brightness relative to medium gray.

And then place it in the zone that gives the emotional impact you want it to have.

That's an idea!

 

[ferider]

If you shoot and develop for scanning (as I do), I suggest a different approach than the several classic ones (zone system, meter/develop for shadow/highlights, etc.) which were all devised for wet printing.

1) Shoot a film under more or less controlled conditions with a given exposure guideline (like expose for zone xxx or similar).
2) Develop with a first recipe (what you used to do, from digitaltruth, or similar).
3) Scan and look at the histogram.

The best print will come from a histogram that uses the full dynamic range of your scanner (in my case 14bit, for instance); you don't want the histogram to be "empty" on the left or right. It should look similar to this right out of the scanner:

If it doesn't, change exposure guideline or development recipe or both. Forget latitude. Latitude covers for emergency or mistakes.

My 2 cents,

Roland.