Confused about "Pushing"

cliveh said:

I sometimes see signs on doors that say push and I pull. I figure this is due to spending too much time looking at negatives and trying to think neg/pos.

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Funny you should mention this as just over the holiday I approached a door with the unlikely moniker "Pull", I did just that and successfully egressed.

Smugly thinking to myself, "I bet everybody else pushes".

markbarendt said:

What all that density means is that Tmax can record a really long range of tones from the scene. That range makes it a great film for toy cameras or for landscapers with really super long scale subjects who are willing to do a fair amount of burn and dodge when they print.

Just for giggles let's use some real numbers and say Tmax can catch a 14-stop brightness range. (Some say more.)

A normal scene measures about 6 stops, zone III to zone VIII. (That's also about what prints on paper normally.)

Bottom line is that for a normal scene/print you might only use half of Tmax's capacity/density range to make that print. (The percentage of used vs unused will vary but this concept is true of most all negative films.)

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According to Ansel Adams, zone V should have density of about .6 to .7 above base+fog for condenser enlarger.

Now, looking at tmax400 tech sheet and assuming zone V spans log -1.66 to -1.33, given normal development that would be density 1. Zone VII (between -1 and .66) would have density of about 1.4, and zone IX density 1.9

Exposing at EI 1600 is essentially putting zone V at -2.33 to -2, and with push processing that would again give density of about 1. But now zone VII is between -1.66 and 1.33 with density of about 1.5, and zone IX would have density over 2!

So it's not just that tmax has huge latitude, it's also very dense given "normal" recommended development times and even denser when pushed. Why are "normal" development times not much shorter?

jernejk said:

According to Ansel Adams, zone V should have density of about .6 to .7 above base+fog for condenser enlarger.

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I think that is specific to the materials available to Ansel Adams.

jernejk said:

Why are "normal" development times not much shorter?

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Normal development times give you about 1.10 over base+fog at the upper end of about 7 stops of subject brightness range. A 2-dimensional subject only has about 5 stops of range (from black to white in full light), the other 2 stops are for shadow detail (so you can make out something dark that happens to be in the shade).

MattKing said:

I think that is specific to the materials available to Ansel Adams.

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I frankly don't know.

But wouldn't a very different material with very different densities imply also very different printing? I'm not sure how negative density correlates to printing, but my guess is each .3 difference in density would give a difference of 1 stop on a grade 2 paper? Wouldn't that imply there should be kind of constant relation between zones and density?

jernejk said:

I frankly don't know.

But wouldn't a very different material with very different densities imply also very different printing? I'm not sure how negative density correlates to printing, but my guess is each .3 difference in density would give a difference of 1 stop on a grade 2 paper? Wouldn't that imply there should be kind of constant relation between zones and density?

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I just saw you were looking at graphs and interpreting some specific numbers.

Paper grades differ by requiring negatives density ranges that differ by about 0.20 per grade.

When it comes to developing film to hit the paper, you can specify what you want to get... Look at the data from the spec sheet or your own tests... and aim for a developing time that gives you the result you want.

It is very easy to get what you want by altering development time.

Here are two extremes you can visualize in your head... Say you want 1.0 density on your negatives in the highlight zones. 1 is an easy number for the math...

If you have a very contrasty subject that spans 3.0 log exposure, and you want about 1.0 density on your in the highlights, then you will want 1 divided by 3... about 0.33 average contrast. Very extreme case, but for me, that is 6 developing minutes in D-76 1:1 for 4x5 film in a tray.

Now imagine another simple math, with closer to a normal subject 2.0 log exposure (1 density divided by 2 log exposure) about 0.50 average contrast. For me, 10 developing minutes.

It is that simple to figure how long to develop your film.

jernejk said:

I frankly don't know.

But wouldn't a very different material with very different densities imply also very different printing? I'm not sure how negative density correlates to printing, but my guess is each .3 difference in density would give a difference of 1 stop on a grade 2 paper? Wouldn't that imply there should be kind of constant relation between zones and density?

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Adams over simplified to make the concepts easier to get for the general public.

The relationship between zones (in scene or on paper) and stops is neither always linear, nor always 1:1, nor are they necessarily tied to any specific density point on the negative.

Adams' density numbers do typically represent the low end of the usable exposure range. The practical advantage of using Adams' numbers is shutter speed.

The paper, say grade 2, is the big limit here, it will only print from a density "range of one" from the negative for a straight print.

Using Adams' numbers as an example, the print/the zones, start from a negative density of .1 and run to the negative density of 1.1, everything outside that range of, one density unit, prints black or white.

It doesn't matter if you expose and develop your TMax 400 to get a total density of 3, you can still only straight print a one density unit range, 1/3 of that negative's range, you have to burn and dodge to get at the rest of the info on the negative.

markbarendt said:

I actually thought that HC-110 did the same thing, I got corrected by PE and others.

Seems that that info is more of an urban legend than a reality. As I remember the suggestion was that the curve was a near duplicate of D-76.

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I haven't personally tested this combination, but I do have curves from the BZTS Plotter app that show there is an upswept curve for TMY in HC110. It's more linear (especially at longer development times) in XTOL 1+1 and in ID-11 1+1 based on the charts that come with the Plotter app. I've only tested this TMY in XTOL, but my results matched the sample curves if I remember correctly (can't access the file right now to be sure).

jernejk said:

Exposing at EI 1600 is essentially putting zone V at -2.33 to -2, and with push processing that would again give density of about 1. But now zone VII is between -1.66 and 1.33 with density of about 1.5, and zone IX would have density over 2!

So it's not just that tmax has huge latitude, it's also very dense given "normal" recommended development times and even denser when pushed. Why are "normal" development times not much shorter?

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jernejk,

You've got a solid grasp on interpreting the data and working with logarithms. Everything you said is accurate. But almost every film will hit Zone IX over 2.0 with a one stop push, that's not a special attribute of TMAX 400.

When you push, you aren't using the Zone System. It isn't common to continue to use Zone System terms when talking about pushing... You are doing weird stuff like... placing shadows on Zone I instead of Zone II. You are placing Zone VII on Zone VI and then developing it back up to Zone VII again. Zone VIII is placed on Zone VII and by development falls too high, probably around Zone IX as you are starting to see, and Zone IX has gone over 2.0

Your print would have reasonable detail for Zone VI but will start to look stark at any higher Zones. You either don't care about those higher Zones, or accept them as part of the graphic effects of pushing.

N developing time IS less than "normal" development times for exactly the reason you are starting to see. And as markbarendt hints, you really want the negative to have a density range around 1.0 from the darkest shadows you want texture to the highlights you want texture. Flare will usually bring your lowest density on the negative up a bit, so you can have your Zone IX above 1.2 or 1.3 and still fit Grade 2 paper.

Thank you all on your valuable input.

I'm trying to understand my error and apply as much science as possible without a proper densitometer - so I just took macro shoots of some negatives to compare them.

This is tmax 400 @ 400 in rodinal 1:100, stand developed: https://www.dropbox.com/s/rhytofyo3vaanib/tmy_400_rodinal_stand.png
Note that the photo was taken on a cloudy day, so no high contrast in scene there.

Now, compared to my push, tmax 400 @ 1600 in HC 110 B 8'30'' : https://www.dropbox.com/s/n7uynhshtn2mtba/tmy400@1600_hc110.png
This looks very, very thin. The histogram is very compressed, and indeed the separation of tones is poor. The only way to compensate is using high grade paper, which makes skin tones harsh, not appropriate for the subject. If anything, this film was probably underdeveloped - even though Kodak's tech sheet suggests even shorter time of 7'30''.

jernejk,

Both of your example shots are workable/printable, the visible density difference is to a great extent an effect of how the shots were taken with your camera.

IMO the depth of field difference (short vs long) between these two shots is probably responsible for almost all of the visible difference. In essence you are comparing apples to oranges here.

The short DOF in the shot of the babe puts the blacks in the 'fuzzy' background, the blacks in the shot of the steps are sharp. Fuzzy = gray, sharp = black; same idea applies at the bright end of the scale.

Using a handheld spot meter, both scenes may have even had the same measured range of contrast. Problem is a spot meter doesn't see your bokeh; it sees sharp not fuzzy, black not gray.

If you had the opportunity to have Adams print these negatives I believe he would simply adjust the paper grade. The step shot might end up on grade 3 paper, the babe maybe on grade 4, the exact grade is irrelevant.

The actual density of the negative would also have been irrelevant to the print as Adams would have simply adjusted the enlarger's brightness or the print time.

markbarendt said:

If you had the opportunity to have Adams print these negatives I believe he would simply adjust the paper grade. The step shot might end up on grade 3 paper, the babe maybe on grade 4, the exact grade is irrelevant.

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If you have a nice daylight scene

- And shoot it with un-coated lens using Trix or HP5 metering for the zone 1 shadows soup in D23 with post borax bath (like Ansel) you will have a negative like one of Ancel's...

- If you then stick a few x4 neutral density filters on the lens and soup it in Miicrophen,for x2 normal then you will move (compress) lots of the zones to between zone 0 and zone 1.
The two prints you do wont be the same, one will look like one of Answel's, nice gossamer clouds, the other 'toilet'.

The old rule I seem to recall was 'don't underexpose and over develop'.

If you like available darkness shots, they are going to be pigs to print.

Noel

Xmas said:

If you have a nice daylight scene

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That's not what the OP has shown us.

markbarendt said:

That's not what the OP has shown us.

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Good point, beautifully presented, but not germane to the (OP's) query.
I suggested a thought experiment, to illustrate that pushing, does really happen, what you do is push data from mid tones into the toes of the shadow. this would be much less meaningful with digital, which does not really have toes, more Procustean, unless you turn up the ISO.
With film it is desirable to use a single coated lens to obtain some (greater) preflashing into what would other wise be zone 0, this tends to compresses the data even more.
And a compensating developer, again compression.
If you are stuck a post borax bath may help instead, or as well, most people can get access to borax, as wash aid or insect killer, two teaspoonfuls into liter easy to do, but again compression.
Each of these makes printing more 'fun' unless you like 'Citizen Kane' stills and your subject has a main light.
I normally retire to coffee shop and OD on muffin and latte when the Weston meter says 'dark'.

Xmas said:

I normally retire to coffee shop and OD on muffin and latte when the Weston meter says 'dark'.

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I on the other hand might just continue shooting using the flash and a 'pod of some sort just like I was at noon.

Different strokes for different folks.