Negative density/contrast question.

rpavich · Dec 6, 2017

Hi,
Just to be upfront, I'm not trying to solve a problem, I'm just curious and I like having things to think about and do, that's just my nature so I was wondering something.

I like how my negatives come out. I like how they print. I did a personal EI test and settled on a developing scheme for my particular film with a particular developer and how it prints on my paper, so there is no issue there but I am curious about something.

I read that negative density of a grey card shot should be .71 and that's what I should be shooting for, but the other day I shot an expodisc shot while out in the sun to get an exposure of middle grey and depending on my settings (1 stop over or 2 stops over or box speed) I was getting .85, .89 and .95
As I said, my negatives print great on grade two filter and getting Dmax out of my paper, so I'm left wondering if using an expodisc is the way to get this mid-grey value. I've seen LOTS of grey cards, they all differ in their shade...some very light, some darker...and I'm wondering if there is one type, brand that's clearly the correct value that you folks know of.

PS: When I try and obtain an expodisc value of .71, I get a VERY VERY low contrast negative that's very hard to print and looks horrible.

bascom49 · Dec 6, 2017

Are your density numbers minus film base plus fog or do they include film base + fog (fb+f) ?
Depending on film type fb+f could easily be 0.12.
0.89 - 0.12 = 0.77, good for a cold light enlarger, at the end of the range for a condensor type enlarger.

rpavich · Dec 6, 2017

bascom49 said:
Are your density numbers minus film base plus fog or do they include film base + fog (fb+f) ?
Depending on film type fb+f could easily be 0.12.
0.89 - 0.12 = 0.77, good for a cold light enlarger, at the end of the range for a condensor type enlarger.

I use an analyzer pro which takes the first reading from the film base and any subsequent readings are matched to that starting point as a "zero" so yes, they are minus the film base+fog.

PS I'm using a Beseler Dual Dichro S head. A color head.

bascom49 · Dec 6, 2017

Than I would guess that the variable to take into consideration would be your development time. In your work flow when obtaining an expodisk value of 0.71 you would need to increase your development time to gain more contrast.
If your shadow areas look good than your film EI of film speed is working for you.
Development time does not affect the shadow areas.
It is possible that your are losing highlight detail in your current workflow with out realizing it depending on subject matter.

rpavich · Dec 6, 2017

bascom49 said:
Than I would guess that the variable to take into consideration would be your development time. In your work flow when obtaining an expodisk value of 0.71 you would need to increase your development time to gain more contrast.
If your shadow areas look good than your film EI of film speed is working for you.
Development time does not affect the shadow areas.
It is possible that your are losing highlight detail in your current workflow with out realizing it depending on subject matter.

Whoa!
Increasing the dev time lowers the value of the middle grey?
I've been thinking about this backwards

My shadow detail is good so I'll experiment with lengthening the dev time.
This has been very informative. I have been under developing my film for a while now.

I guess the culprit wasn't that my grey standard was off, it was pointing to my developing time/shooting speed issue.

bascom49 · Dec 6, 2017

No, increasing development time does not lower middle grey, it increases the density. If I understood correctly, you like your negatives with the higher density numbers, and are getting a lack of contrast when you use the lower value, 0.71.
I'm thinking when exposing for the 0.71 value as middle grey you then need to increase your development time above what you are typically using when exposing for the higher values, .85, .89 and .95.

It is possible that your current development time may be too high and that you may be losing detail in the upper ranges.

Not being familiar or having used an expodisc I'm guessing here and assuming that the expodisc is working for middle grey.

MattKing · Dec 6, 2017

I wonder where someone got the idea that the negative density of any particular grey card "should" be any particular number.
As you have observed, grey cards do vary in their reflectance.
There is an argument that a grey card that happens to have a reflectance of exactly 18% may very well provide a useful 0.71 reference if one is trying to determine exposure for scenes with an average range of reflectances, but do your photographic subjects exhibit that range?
Grey cards are great as a reference. You do though have to interpret the results from your grey card.
Work backwards. Achieve a negative that you like to work with that includes a grey card, take a reading of the grey card from that negative and then take that reading as a useful reference point for scenes with some similarity to the one that resulted in the negative you like.

Bill Burk · Dec 6, 2017

If I look at the characteristic curve for a normally developed black and white negative film and find where it intersects 10 times the speed point I can see where the density could be found to be in the vicinity of 0.71

So you rate the film at its rated speed and spotmeter anything using that recommended shutter speed and f/stop. Then whatever it is that you metered may measure 0.71 density. Sure.

Did you have a personal exposure index that’s half the rated speed? Then you would expect higher density and you would get nice negatives for printing.

The 0.71 must assume rated film speed and recommended development time.

rpavich · Dec 6, 2017

bascom49 said:
No, increasing development time does not lower middle grey, it increases the density. If I understood correctly, you like your negatives with the higher density numbers, and are getting a lack of contrast when you use the lower value, 0.71.

True.

I'm thinking when exposing for the 0.71 value as middle grey you then need to increase your development time above what you are typically using when exposing for the higher values, .85, .89 and .95.

Ok...I guess I worded my response wrong, I would have assumed that if I was getting a higher number and wanted a lower one, I'd require LESS exposure time and a flatter neg.

It is possible that your current development time may be too high and that you may be losing detail in the upper ranges.

It doesn't appear to be the case.

Not being familiar or having used an expodisc I'm guessing here and assuming that the expodisc is working for middle grey.

Click to expand...

True. It's a white opaque disk like a filter that you hold over your lens and when you point it at the light source, it is supposed to provide correct exposure and white balance reference.

Click to expand...

rpavich · Dec 6, 2017

Bill Burk said:
If I look at the characteristic curve for a normally developed black and white negative film and find where it intersects 10 times the speed point I can see where the density could be found to be in the vicinity of 0.71

So you rate the film at its rated speed and spotmeter anything using that recommended shutter speed and f/stop. Then whatever it is that you metered may measure 0.71 density. Sure.

Did you have a personal exposure index that’s half the rated speed? Then you would expect higher density and you would get nice negatives for printing.

The 0.71 must assume rated film speed and recommended development time.

Yes, my personal E.I. varies from film to film and conditions to conditions.
For example: for normal regular contrast shooting, sunny day (not drizzly and rainy over cast) I shoot HP5 at 100 speed and develop at 20% less than the recommended box time. That results in a negative that prints perfectly and effortlessly at Dmax in the darkroom on the paper that I use. The blacks are deep black, the highlights are bright but still have some detail and the tones are nicely distributed. The prints look good. For overcast, drizzyly, rainy, low contrast conditions I shoot at box speed and develop at box speed or just barely slightly over. That also results in a very nice negative that has contrast but the highlights are not blocked and the shadows still have detail.

l

rpavich · Dec 6, 2017

MattKing said:
I wonder where someone got the idea that the negative density of any particular grey card "should" be any particular number.
As you have observed, grey cards do vary in their reflectance.
There is an argument that a grey card that happens to have a reflectance of exactly 18% may very well provide a useful 0.71 reference if one is trying to determine exposure for scenes with an average range of reflectances, but do your photographic subjects exhibit that range?
Grey cards are great as a reference. You do though have to interpret the results from your grey card.
Work backwards. Achieve a negative that you like to work with that includes a grey card, take a reading of the grey card from that negative and then take that reading as a useful reference point for scenes with some similarity to the one that resulted in the negative you like.

That may be what ends up happening, I don't know. I'm just a little perplexed at why. I think part of it is that I've got my facts backwards on how the density numbers run. In other words to get a .75 when I now have been getting an 89, I'd have to develop longer and to me (being a noob) that's counter intuitive. That's all.

Bill Burk · Dec 7, 2017

rpavich said:
I think part of it is that I've got my facts backwards on how the density numbers run. In other words to get a .75 when I now have been getting an 89, I'd have to develop longer...

It’s not counter-intuitive. It’s wrong.

If you get .89 and want .75 then you develop less. I think you read something into what bascom49 wrote that isn’t there.

Meanwhile, it’s OK to think of 0.71 at rated film speed as a benchmark for where normal is designed to be. It’s really “the least” exposure for an “excellent” print. That is about where ASA speed and recommended development brings the metered point up to in density.

Then knowing where you are from there you make your departures. Don’t try for 0.71 when you rated HP5 plus at EI 100 and developed it less. That’s 0.6 to the right... and about 0.3 up... so it would be likely to hit 1.01

p.s. Are you metering with spotmeter or incident metering? It may throw out much of what I said if you incident meter then shoot a gray target

rpavich · Dec 7, 2017

Bill Burk said:
It’s not counter-intuitive. It’s wrong.

If you get .89 and want .75 then you develop less. I think you read something into what bascom49 wrote that isn’t there.

ahh! Ok, thanks for clarifying.

Meanwhile, it’s OK to think of 0.71 at rated film speed as a benchmark for where normal is designed to be. It’s really “the least” exposure for an “excellent” print. That is about where ASA speed and recommended development brings the metered point up to in density.

Then knowing where you are from there you make your departures. Don’t try for 0.71 when you rated HP5 plus at EI 100 and developed it less. That’s 0.6 to the right... and about 0.3 up... so it would be likely to hit 1.01

I just double checked and got .95 so you are right.

Are you saying that what I'm getting by shooting at 100 and developing less is equivalent to shooting at 400 and developing at box and that my .95 to 1.0 is actually OK?

p.s. Are you metering with spotmeter or incident metering? It may throw out much of what I said if you incident meter then shoot a gray target

I'm using the cameras meter and the expodisc. It covers the lens.

The thing that's got me perplexed about the whole thing is this: when I shoot HP5 at 400 and develop normally, I get negatives that are underexposed, that is to say, when I print for just Dmax my images are dark.

If I shoot at 200, they improve but are not where they should be, if I shoot at 100 then I get nice exposures when printed at Dmax on grade 2. The highlights are very bright but without lost detail and the shadows are good.

So if doing that results in nice negs that print very well and look great without effort, then the fact that I'm getting .95 to 1.0 density from the expodisc is perplexing and the only thing that I can think is that the expodisc is reporting the density incorrectly...something isn't making sense.

Just for a check, I ordered a Delta Grey Card from B&H as a secondary check...it's not arrived yet.

As I said at the start, I LIKE my negs when shooting 2 stops under box and developing like I am so I'm not trying to solve that issue, it's just that I'm trying to learn and keep myself occupied.

Bill Burk · Dec 7, 2017

Ah that’s the thing. I like my TMY-2 negs when I shoot at 250. And I have gotten nice prints from them when shot at 64. So I can understand wanting to shoot HP5 Plus at 100. I would do the same.

The film is really 400, that relates to how much density you get for the light that hits.
When you use the expo disc at 100 you are going to get a density around 1.0 - you are hitting the film with more light and that’s increasing the density.

You can shoot at 400 and print lighter, you will know it’s crummy but it’ll please most other people who don’t know the difference.

rpavich · Dec 7, 2017

Bill Burk said:
Ah that’s the thing. I like my TMY-2 negs when I shoot at 250. And I have gotten nice prints from them when shot at 64. So I can understand wanting to shoot HP5 Plus at 100. I would do the same.

The film is really 400, that relates to how much density you get for the light that hits.
When you use the expo disc at 100 you are going to get a density around 1.0 - you are hitting the film with more light and that’s increasing the density.

You can shoot at 400 and print lighter, you will know it’s crummy but it’ll please most other people who don’t know the difference.

That's actually what I was doing, shooting at 400 and I'd have to make contact sheets that were not Dmax and my prints were (much of the time) just blah. Not vibrant and strong. I had read an article about how to find your EI; first shoot at 100, 125, 160, 200 etc, then check the shadows and print what has good shadow detail. Then think about the printing, look at the highlights, if they are lacking then increase the dev time until they are where the should be and I was surprised to see that I was shooting at 100 with HP5 and developing at 20% less than box and 10% less than box looks even better for highlights.
Now, my prints print excellent at grade 2 with strong white (but not blown) highlights and nice deep vibrant shadows and blacks where they should be and the middle tones are really nice. I'm very happy with them.

So just to clarify because I'm not the sharpest tool in the shed; I cannot get and shouldn't expect .75 from this set up. If I wanted that value, I'd shoot at 400 and adjust the development to something more than what I'm doing now.

Would the net result be the same? In other words, if I got adequate shadow detail from rating at ISO 400, and then adjusted the developing time to be MORE than box...I'd get negs that printed as well as I am now?

MattKing · Dec 7, 2017

As I read it, the ExpoDisk is designed to mimic the performance of an incident meter,
Is that how you are using it?

rpavich · Dec 7, 2017

MattKing said:
As I read it, the ExpoDisk is designed to mimic the performance of an incident meter,
Is that how you are using it?

True.

Doremus Scudder · Dec 7, 2017

Don't touch a working system.

Many of us, me included, like negatives with a little more density than "standard" just so we have adequate shadow detail for dodging and a longer scale when developing a bit less than "recommended." If you are not having problems with grain or printing the highlights (i.e., no shouldering out), then be happy and keep doing what you're doing.

As for the theory: all those recommended density numbers are predicated on a particular contrast index and film speed, which may or may not be ideal for what you want. Throw an exposure/development system, like the Zone System, into the mix along with metering technique, lens/shutter inconsistencies, etc., etc. and things are all over the place.

It's great to understand the theory, but keep in mind that the negative is only an information carrier for making the final print. It really doesn't matter what densities on the negative produce what densities on the print as long as it is what you are after.

Best,

Doremus

rpavich · Dec 7, 2017

t/

Doremus Scudder said:
Don't touch a working system.

Many of us, me included, like negatives with a little more density than "standard" just so we have adequate shadow detail for dodging and a longer scale when developing a bit less than "recommended." If you are not having problems with grain or printing the highlights (i.e., no shouldering out), then be happy and keep doing what you're doing.

As for the theory: all those recommended density numbers are predicated on a particular contrast index and film speed, which may or may not be ideal for what you want. Throw an exposure/development system, like the Zone System, into the mix along with metering technique, lens/shutter inconsistencies, etc., etc. and things are all over the place.

It's great to understand the theory, but keep in mind that the negative is only an information carrier for making the final print. It really doesn't matter what densities on the negative produce what densities on the print as long as it is what you are after.

Best,

Doremus

Thanks Doremus, I wasn't planning on revamping anything unless it needed to be revamped. As I mentioned a couple of times, I'm doing this out of fun and for information. Unlike a lot of folks here on the APUG I only have a couple of years of photography experience and so this is all new and interesting to me. I like to learn and this is a good group to learn from.

btaylor · Dec 7, 2017

A couple of thoughts: I am not familiar with the expodisc, I don't have one, but I do have a variety of supposedly 18% gray cards. You do have to be careful with their placement-- they can all vary depending on their angle to a light source, this is especially true of angling toward the sky. If the brightness varies on this "constant" you can be in for trouble down the line. Second, while I don't use a densitometer all the time, I found my ideal density for a correctly exposed gray card was .85- .89, consistent with what you are finding for making good prints at grade 2.

rpavich · Dec 7, 2017

btaylor said:
A couple of thoughts: I am not familiar with the expodisc, I don't have one, but I do have a variety of supposedly 18% gray cards. You do have to be careful with their placement-- they can all vary depending on their angle to a light source, this is especially true of angling toward the sky. If the brightness varies on this "constant" you can be in for trouble down the line. Second, while I don't use a densitometer all the time, I found my ideal density for a correctly exposed gray card was .85- .89, consistent with what you are finding for making good prints at grade 2.

Well isn't that interesting!

Doremus Scudder · Dec 8, 2017

Keep in mind that the negative density has absolutely no fixed relationship to print density. One can print a single negative density all the way from max black to max white on a print by varying print exposure. What does make a difference is the spacing of the densities on the negative relative to the contrast of the paper. As long as the density range on the negative is not compromised by shoulder and toe (this latter to a lesser extent), then the actual density makes a difference only in regard to graininess. This becomes less of an issue as film size increases and enlargement factor decreases, which is why many large-format users give a generous safety factor when exposing (and why lots of smaller film users spend a lot of time getting their exposure to just the minimum needed to make a good print).

There's another thing to consider: Not all negatives print well without manipulations. More and more I find myself making a contrastier negative than fits the paper contrast range and then using dodging and burning, etc. to tame the extremes; all this in order to get more separation in important shadow or mid-tone areas. In cases like this, and with a print exposure based on a highlight area, the shadows print too dark without dodging. If I had simply exposed for the mid-tone, there would be no detail in the shadows to dodge for. Extra exposure is often needed so that detail is there, with adequate separation, for dodging. Many would simply call this negative overexposed and overdeveloped...

The point is, the exact densities on the negative are only interesting in relation to each other and the distribution of negative densities has more to do with the print plan than any given standard or some mistaken notion that when negative density range is matched with print contrast a good print will result.

Best,

Doremus

rpavich · Dec 8, 2017

Doremus Scudder said:
Keep in mind that the negative density has absolutely no fixed relationship to print density. One can print a single negative density all the way from max black to max white on a print by varying print exposure. What does make a difference is the spacing of the densities on the negative relative to the contrast of the paper. As long as the density range on the negative is not compromised by shoulder and toe (this latter to a lesser extent), then the actual density makes a difference only in regard to graininess. This becomes less of an issue as film size increases and enlargement factor decreases, which is why many large-format users give a generous safety factor when exposing (and why lots of smaller film users spend a lot of time getting their exposure to just the minimum needed to make a good print).

There's another thing to consider: Not all negatives print well without manipulations. More and more I find myself making a contrastier negative than fits the paper contrast range and then using dodging and burning, etc. to tame the extremes; all this in order to get more separation in important shadow or mid-tone areas. In cases like this, and with a print exposure based on a highlight area, the shadows print too dark without dodging. If I had simply exposed for the mid-tone, there would be no detail in the shadows to dodge for. Extra exposure is often needed so that detail is there, with adequate separation, for dodging. Many would simply call this negative overexposed and overdeveloped...

The point is, the exact densities on the negative are only interesting in relation to each other and the distribution of negative densities has more to do with the print plan than any given standard or some mistaken notion that when negative density range is matched with print contrast a good print will result.

Best,

Doremus

Thanks Doremus, I have stumbled on the fact that I like negatives that are more developed than I used to have too.

Negative density/contrast question.

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