What happens when...

[Dev]

What happens when you expose your film normally (box speed), but over-develop it as if you were push processing by +1 stop?

Also, what happens when you underexpose your film by -1 stop and over-develop by +1 stop?
Would the resulting image appear as if you had shot it at box speed and developed normally, effectively 'cancelling-out' each other?

 

[chriscrawfordphoto]

What happens when you expose your film normally (box speed), but over-develop it as if you were push processing by +1 stop?

Also, what happens when you underexpose your film by -1 stop and over-develop by +1 stop?
Would the resulting image appear as if you had shot it at box speed and developed normally, effectively 'cancelling-out' each other?

Both situations will give increased contrast. The one underexposed one stop will have slightly less shadow detail.

 

[tedr1]

I like charts, sometimes they show what is going on better than words can.

The meaning of "overdevelop" is usually taken to mean an increase in development time.
This chart shows what happens to the contrast of a film when time is increased. Note that at the left hand (lower end) of the curve not much changes (this is also known as the "toe" of a film curve) however at the right hand side there are big changes. The left hand end are where shadows are recorded, the right hand end is where highlights are recorded. An increase in development time causes a significant increase in highlight density (which makes the highlights in the print brighter) this is what is meant by a change of contrast, the difference between shadow density and highlight density, more development causes increased contrast.

 

[Rudeofus]

Here is series of charts from a recent test I made. Test was done with Promicrol 1+14 on Tri-X contact printed through T2115 Stouffer wedge. The two test rows were done with different exposures, therefore please make no attempts to overlay these graphs.

Graph 1 is an H&D plot, i.e. transmission density over exposure for different developer times, all times somewhere around the Massive Dev Chart time of 13 minutes. There is this odd thing, that the 14.5 minutes plot strangely overlaps the 16 minute plot, which should tell how accurate or reproducible these test are (i.e. they aren't). They still show a standard tendency: as development time goes up,

1. contrast goes up
2. fog goes up
3. threshold speed doesn't change much

The second chart shows H&D graphs for developer times which deviate more from the Massive Dev Chart time of 13 minutes. What becomes obvious now is the extended toe region we get when we underdevelop film. Contrast is visibly reduced, and useful image contrast requires one more more extra stops of light.

Once you get close to the recommended dev time of 13 minutes, threshold speed doesn't change much any more. Extra development gives additional contrast in the toe region, which could in some cases create useful shadow detail where normal development wouldn't.

 

[MattKing]

Changing the exposure has a lot of effect on how much of the shadow detail is recorded, but has very little effect on how much of the highlight detail is recorded.
Changing the development has very little effect on the speed or sensitivity of the film, but has a significant effect on how the contrast builds in the film.
So in your first case, you build contrast, but don't really add any recorded detail. You might even lose highlight detail.
In your second case, you lose shadow detail, but build contrast.

 

[Dev]

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I'm still not quite understanding. This graph shows that if I overexpose, I'll have LESS contrast. Also, if I underexpose, I'll have LESS contrast.

 

[MattKing]

I'm still not quite understanding. This graph shows that if I overexpose, I'll have LESS contrast. Also, if I underexpose, I'll have LESS contrast.

That only applies if your posited changes move your results either all the way up on to the shoulder of the graph or all the way down to the toe.
The changes you first proposed won't move the results nearly that much.

 

[mshchem]

If you look at development times for TMY at 400 (box speed) and at 800, pushed 1 stop, the development times in XTOL are identical, the 800 speed has less shadow detail recorded.
Experts chime in please, but, the zone system/under/over development, wasn't this much easier to do with the older films. Ektapan, Super XX etc.???
Mike

 

[MattKing]

If you look at development times for TMY at 400 (box speed) and at 800, pushed 1 stop, the development times in XTOL are identical, the 800 speed has less shadow detail recorded.
Experts chime in please, but, the zone system/under/over development, wasn't this much easier to do with the older films. Ektapan, Super XX etc.???
Mike

TMY metered at 800 isn't pushed, it just has less exposure than if it is metered at 400.
You don't "push" film at the exposure stage, you "push" it at the development stage.
The reason that Kodak doesn't recommend an increase in development because the increase in development always involves a compromise. While the increase in development improves the contrast in an otherwise "exposed less than optimum" negative, it usually decreases the quality of how the highlight details are rendered.
In Kodak's judgment, the shadow detail on the 800 metered film is of acceptable quality whether or not the development is changed, and the contrast improvement one gains from increasing the development of the 800 metered film is more than offset by the reduction in quality of the highlight detail. So Kodak doesn't recommend more development.
For clarity, and even if it is redundant, increasing the development makes essentially no difference to the ability of the film to give good shadow detail in under-exposed films.
And yes, with respect to new vs. older films, the newer films like the T-Max films tend to offer longer straight sections in their characteristic curves, so they encourage the photographer to use printing controls instead of development controls to achieve similar results.

 

[Gerald C Koch]

Reading about something and actually seeing the results are two very different things. I would therefor suggest trying things yourself. One the things you need in photography is to be completely familiar with your materials. Such experiments would be a good learning exercise. Take good notes and save sample prints for future reference.

 

[LifesShort]

Here is a great explanation with examples of how exposure and development affect your results:
http://www.theonlinedarkroom.com/p/how-to-read-negative.html

 

[Juan Valdenebro]

What happens when you expose your film normally (box speed), but over-develop it as if you were push processing by +1 stop?

Also, what happens when you underexpose your film by -1 stop and over-develop by +1 stop?
Would the resulting image appear as if you had shot it at box speed and developed normally, effectively 'cancelling-out' each other?

It depends on scene contrast...
For overcast scenes, the answer to your two questions is "it doesn't really matter too much."
For direct sunlight scenes, the answer to the first question is "you'll start burning your highlights", and the answer to the second question is "apart from blocked highlights, you'll lose some shadow detail."

 

[Juan Valdenebro]

I'm sure Kodak's recommendation about keeping the same development time for EI800 use, makes total sense for high contrast scenes only, because -as Matt and others said- highlights can suffer from overdevelopment.
In the case of soft light, it would be interesting to see if forum members prefer to develop a little longer at EI800 as I do, for a more natural middle grays rendition. I include the gray card in my tests, and I prefer it when it looks like it is, instead of the darker tone it easily gets when development is a bit weak after that stop of underexposure...