AA's Value I density targets

[markbau]

Just for fun I had a few frames left on a film so decided to do a Value I density test. Using TX 120 I shot a black target on zone 1 at EI 200 and 400. Zeroing my densitometer on the film base the EI 200 reads at .05 and the EI 400 read .01.

In AA's book "The Negative" He says to aim for a Value 1 of 0.09 - 0.11 above fb+f. If I followed this I would be rating Tri X at EI 100. I'm very happy with my negs at EI 200 so don't plan to change anything but was wondering if anyone could explain the difference. The film was hand developed in D76 1:1 for 9 minutes, 30 second agitations.

 

[markbau]

Probably a technical error.

You are 3 stops off.

EI 400 expected = 0.10
EI 400 observed = 0.01
0.01-0.10 = 0.9 = 3 stops.

What do you mean "technical error"? And what do you mean I am 3 stops off. AA wasn't expecting a density of 0.10 when rating it at its box speed. Later in the book he says he rates TX (Not TXP) at EI 200 so it's fair to say that his rating at EI 200 got him 0.10. The spot meter I used has recently been checked by a camera tech and found to be within factory specs. The camera was checked a year ago for shutter accuracy and I've never questioned it. The light source was constant.
AA says 0.09 - 0.11. I got 0.05 at EI 200 which is which is 1 1/3 stop from 0.09. Not 3 stops. (I don't know anyone who rates B&W film at its box speed.

 

[Raghu Kuvempunagar]

Just for fun I had a few frames left on a film so decided to do a Value I density test. Using TX 120 I shot a black target on zone 1 at EI 200 and 400. Zeroing my densitometer on the film base the EI 200 reads at .05 and the EI 400 read .01.

Just curious to know the Zone VII and Zone VIII densities you got.

 

[bernard_L]

to do a Value I density test. Using TX 120 I shot a black target on zone 1 at EI 200 and 400.

Why

 

[bernard_L]

to do a Value I density test. Using TX 120 I shot a black target on zone 1 at EI 200 and 400.

Why a black target? Gray will do. White also. As long as it's placed on Zone.I, i.e. underexposed by
{4 stops for ZI true believers | 3+1/3 stops for ISO true believers}
wit respect to the meter reading for that very target. See,e.g., this:
https://www.photrio.com/forum/threa...in-camera-exposure.164449/page-2#post-2143091

 

[markbau]

Why a black target? Gray will do. White also. As long as it's placed on Zone.I, i.e. underexposed by
{4 stops for ZI true believers | 3+1/3 stops for ISO true believers}
wit respect to the meter reading for that very target. See,e.g., this:
https://www.photrio.com/forum/threa...in-camera-exposure.164449/page-2#post-2143091

What difference would it make if it's mid grey, white or black? As long as its metered and placed on zone I.
Pointing a spotmeter at any target gives you a zone V exposure, closing down the aperture by 1 stop gives you zone IV, another stop gives you zone III etc until you close down 4 stops when you get to zone I. You have now placed the target on zone I.

 

[markbau]

Just curious to know the Zone VII and Zone VIII densities you got.

I only tested for zone I which is what you normally test to determine your personal EI rating for a given film.

 

[Raghu Kuvempunagar]

I only tested for zone I which is what you normally test to determine your personal EI rating for a given film.

No problem.

 

[Anon Ymous]

I only tested for zone I which is what you normally test to determine your personal EI rating for a given film.

So, what if you ridiculously overdevelop your film and you get a density 0,1 above film base plus fog at an unreasonably high exposure index?

 

[markbau]

So, what if you ridiculously overdevelop your film and you get a density 0,1 above film base plus fog at an unreasonably high exposure index?

I don't even know where you are going with this question/hypothesis. But this is why I'm often hesitant about posting in this group. Ask a pretty simple question and next thing people are trying to split the atom and wondering if the result will be influenced by the fact that you are wearing corduroy and listening to Pink Floyd.

 

[Raghu Kuvempunagar]

You are 3 stops off.

EI 400 expected = 0.10
EI 400 observed = 0.01
0.01-0.10 = 0.9 = 3 stops.

I didn't quite get you. Isn't 0.10 - 0.01 = 0.09 and not 0.9?

 

[Sal Santamaura]

Assuming you're pleased with the contrast of pictorial negatives on that roll (i.e. they print well using your typical paper/developer/etc.), you really do have an approximately EI100 film/development combination. That simply means Zones I and II are blacker and less detailed in the the print than they would be had you exposed at EI100. 400TX is very commonly considered a less-than-EI400 film in D-76. If you're happy with the way low values look in your prints, don't worry, be happy.

If instead you'd like to experiment to see how different low values would appear in your prints were the film given sufficient exposure to satisfy Adams' criterion, shoot another roll, of a single scene in unchanging lighting, starting with your usual exposure protocol, then increasing by one and then by two stops (i.e. EI200 and EI100). Develop the film and print as you typically do. Evaluate. Decide.

 

[Anon Ymous]

I don't even know where you are going with this question/hypothesis. But this is why I'm often hesitant about posting in this group. Ask a pretty simple question and next thing people are trying to split the atom and wondering if the result will be influenced by the fact that you are wearing corduroy and listening to Pink Floyd.

What I'm merely trying to point out is that using a single point (0,1 above fb+f) to determine a "correct" exposure index can be problematic. There's what is considered a "normal" contrast and in order to evaluate it you will need more zone densities. I suspect @Raghu Kuvempunagar asked because of this, perhaps he suspected lower than "normal" contrast in your test case, which could explain the discrepancy. Generally speaking, a 2 stop speed decrease isn't what we would expect from zone system testing, it's a tad too much and people suspect some sort of technical error.

 

[Paul Howell]

Seems like splitting atoms, but when I took the summer zone workshop with Minor White we had the use of very good densitometer. Minor White was of the opinion that shooting a single zone exposure target with one frame would not provide all the information needed to determine E.I you need to plot true contrast curve. Zone 1 may suggest E.I of 100, but Zone V may be different. As I have never owned a densitometer I shoot a ring around to find an E.I that works for me. Also useful to remember that any change in paper contrast, paper developer, film developer may change your E.I. If shooting Trix Pro at 200 works for you as it does for many people.

 

[Deleted member 88956]

Just for fun I had a few frames left on a film so decided to do a Value I density test. Using TX 120 I shot a black target on zone 1 at EI 200 and 400. Zeroing my densitometer on the film base the EI 200 reads at .05 and the EI 400 read .01.

In AA's book "The Negative" He says to aim for a Value 1 of 0.09 - 0.11 above fb+f. If I followed this I would be rating Tri X at EI 100. I'm very happy with my negs at EI 200 so don't plan to change anything but was wondering if anyone could explain the difference. The film was hand developed in D76 1:1 for 9 minutes, 30 second agitations.

You were happy with negatives, then shot some tests anyways, which suggest you should NOT be happy with your negatives? I'm just wondering the point of testing when apparently none was needed.

 

[takilmaboxer]

The zone 1 density is not sufficient information by itself. You also need to measure the contrast gradient: the curve itself. If your zone 1 is 0.1 and your gradient is 0.56 (old Kodak standard), then you really do have an ASA 100 film, with your camera and your meter.
But that's a technical definition. If using ASA 200 produces negatives you like and that are readily printable, then you have an ASA 200 film.

 

[Raghu Kuvempunagar]

I suspect @Raghu Kuvempunagar asked because of this, perhaps he suspected lower than "normal" contrast in your test case, which could explain the discrepancy.

Yes, you're right. But it is possible that the negatives are fine at EI:200 and there's some problem with the densitometer or the test procedure. I would suggest OP to measure, at minimum, Zones 1, 2, 5 and 8 the next time he feels like doing a test like this. The extended set of readings will give a more clear picture.

 

[ic-racer]

I didn't quite get you. Isn't 0.10 - 0.01 = 0.09 and not 0.9?

Oops. Never mind. Post deleted due to own stupidity.

 

[MattKing]

I'd be concerned about the role played by the black target - reflectivity, surface sheen, etc. - and the metering technique for a reading from a black subject.
In an "idealized" world, a truly black subject would give you no reading whatsoever, no matter what the light levels are.
But as we aren't discussing telescopes and photographing black holes, it seems to me that it is better to use something like a grey towel with lots of texture instead.

 

[Paul Howell]

That's a good point, a Kodak gray card has a known value, but picking what I might think is a zone target 1 might be 1.5 or 2, black is a very hard color, or lack of color to judge.

 

[MattKing]

That's a good point, a Kodak gray card has a known value, but picking what I might think is a zone target 1 might be 1.5 or 2, black is a very hard color, or lack of color to judge.

It isn't necessary to use a grey card - anything with a reasonable amount of reflectivity and some observable texture - a grey towel being an example - is a good subject.
You then place your reading from that subject on the Zone that you are seeking to target.

 

[ic-racer]

What do you mean "technical error"? And what do you mean I am 3 stops off. AA wasn't expecting a density of 0.10 when rating it at its box speed. Later in the book he says he rates TX (Not TXP) at EI 200 so it's fair to say that his rating at EI 200 got him 0.10. The spot meter I used has recently been checked by a camera tech and found to be within factory specs. The camera was checked a year ago for shutter accuracy and I've never questioned it. The light source was constant.
AA says 0.09 - 0.11. I got 0.05 at EI 200 which is which is 1 1/3 stop from 0.09. Not 3 stops. (I don't know anyone who rates B&W film at its box speed.

Sorry, for the confusion, I deleted the post.

 

[Paul Howell]

It isn't necessary to use a grey card - anything with a reasonable amount of reflectivity and some observable texture - a grey towel being an example - is a good subject.
You then place your reading from that subject on the Zone that you are seeking to target.

So a gray towel that could be zone IV to VI will provide a correct zone V reading?

 

[MattKing]

So a gray towel that could be zone IV to VI will provide a correct zone V reading?

Yes.
It can also provide a correct meter reading for the purposes of placing the exposure in order to render it in Zone I, Zone II, Zone II, Zone IV, Zone V, Zone VI Zone VII etc.

 

[markbau]

I'll try to answer a few posts with one reply.

VTLD. I'm very happy with TX at 200, I just had a few spare frames and as I purchased a densitometer (for alt process) thought I'd see how close my zone 1 is to AA's recommendations.

Raghu (and others) regarding only testing for zone 1 and not V and VII. AA's tests involve first finding your personal EI for your film by shooting a series of negs exposed at zone I. After establishing your personal EI you then shoot another series of zone VII and find out your development time.

MattKing. First of all, using a towel could be problematic unless the towel is stretched tightly over a flat surface, if you just drape a towel over a chair or something you will get folds that will have shadows in them, you need a very flat surface for a test such as this as you don't want subtle variations caused by a not perfectly flat surface. Regarding the choice of a black card. I fail to see what difference it would make. I'd be more concerned with using a lighter card as that may introduce flare. The main concern is to take a meter reading and then "place" the reading on zone I.

I am currently putting my last two rolls of Verichrome pan through my camera and will not be wasting any frames on tests but will re-test TX when I next have it in my camera.