MGIV designed for T-gain films, rumor?

brian steinberger · Mar 19, 2011

Very interesting Mark. I never thought about it that way. I just assumed that if you gave less exposure the highlights wouldn't reach the shoulder of the film. So they would be falling in the middle of the curve, on the straight line part. This does make sense though right?

markbarendt · Mar 19, 2011

It's a lot easier to understand when you remember that the film speed (the shadow point) doesn't really change much. See The Negative, Adams; contraction and expansion.

hrst · Mar 19, 2011

markbarendt said:
It's a lot easier to understand when you remember that the film speed (the shadow point) doesn't really change much. See The Negative, Adams; contraction and expansion.

It's a very good "rule of thumb" to start the explanation of the basics of basics. This is a typical kind of simplification that locks down one parameter completely to lower the number of parameters to think about.

But, there are also too much people who take that rule to the letter. At some point we have to admit that it's just a simplification. The lack of this action has given born to some common internet legends, such as:

"Push processing does not increase film speed at all" - not true
"Push processing does not improve 'shadow detail' compared to normal processing" - not true.

First, even though development time doesn't change shadow point much, it still changes it, and sometimes this can be significant.

Second, what's "shadow point"? Depending on where you put the shadow point, the fact how much it moves changes drastically. "Push processing" underexposed negs is based on the fact that you compromise the shadow point a little bit and move it right - after that, the push processing magically raises this shadow point considerably, and even if your deepest shadows are blocked, your not-so-deep shadows, or lower midtones can gain from push processing, compared to normal processing.

RalphLambrecht · Mar 19, 2011

markbarendt said:
... It is ... desirable ... to make printing choices that only print from the film's straight line ...

Exactly!

RalphLambrecht · Mar 19, 2011

hrst said:
... Some people prefer low contrast with lots of shadow detail, some people prefer punchy, grainy pictures with blocked shadows. ...

... and some people like what they get, because they don't know how to get anything else.

hrst said:
... In the middle of these extremes, there also exists the choice selected most often: trust the manufacturer and get the "average" look.

Most people think that what they do is what most people do.

Photo Engineer · Mar 19, 2011

Both Haist and Mees have shown this clearly since back in the 50s. Film and paper have not changed except for the better, coming closer to this ideal.

Figure 1 Idealized negative curve
Figure 2 and 3, density range vs exposure
Figure 4 area of the negative of first excellent print

Mees points out that the greatest number of excellent prints falls between points A and Z.

PE

hrst · Mar 19, 2011

Ralph:

And 50% of people are more stupid than average person.

And many of us seem to like meaningless, idle chatter .

RalphLambrecht · Mar 19, 2011

hrst

We really need to be careful to assume that what we do is what most people do. Most people are not even on APUG. Heck, most photographers are not even on APUG. The rest is pure assumption.

RalphLambrecht · Mar 19, 2011

Photo Engineer said:
Both Haist and Mees have shown this clearly since back in the 50s. Film and paper have not changed except for the better, coming closer to this ideal.

Figure 1 Idealized negative curve
Figure 2 and 3, density range vs exposure
Figure 4 area of the negative of first excellent print

Mees points out that the greatest number of excellent prints falls between points A and Z.

PE

I interpret this to: Stay as much as you can on the straight line of the film. A method that has always served me well. I 'overexpose' to create detailed shadows, and I make sure to have sufficient active developer to avoid 'rolling-off' highlights. This leaved me enough flexibility to emphasize or subdue image features as necessary during printing.

markbarendt · Mar 19, 2011

hrst said:
It's a very good "rule of thumb" to start the explanation of the basics of basics. This is a typical kind of simplification that locks down one parameter completely to lower the number of parameters to think about.But, there are also too much people who take that rule to the letter. At some point we have to admit that it's just a simplification. The lack of this action has given born to some common internet legends, such as:

"Push processing does not increase film speed at all" - not true
"Push processing does not improve 'shadow detail' compared to normal processing" - not true.

These aren't my thoughts. That is why I referenced The Negative and avoided absolutes. Adams lays out the change in shadow point with +/- development.

As to shadow detail improvements, that's a whole different can of worms.

Pushing makes contrasty negatives, so you may be able to get better defined shadow contrast but, and it's a big but, that "better" shadow detail is absolutely linked to exposure placement.

If you want more shadow detail you have to be willing to give up something at the far end of the curve.

hrst said:
First, even though development time doesn't change shadow point much, it still changes it, and sometimes this can be significant.

1/3 of a stop speed per each stop of push is what I remember.

hrst said:
Second, what's "shadow point"? Depending on where you put the shadow point, the fact how much it moves changes drastically. "Push processing" underexposed negs is based on the fact that you compromise the shadow point a little bit and move it right - after that, the push processing magically raises this shadow point considerably, and even if your deepest shadows are blocked, your not-so-deep shadows, or lower midtones can gain from push processing, compared to normal processing.

Magic you say?

I think not.

You have actually laid out what really happens. Some shadow details are sacrificed in a compromise with the film, in order to get what's actually more important.

That's an exposure placement choice.

Photo Engineer · Mar 19, 2011

RalphLambrecht said:
I interpret this to: Stay as much as you can on the straight line of the film. A method that has always served me well. I 'overexpose' to create detailed shadows, and I make sure to have sufficient active developer to avoid 'rolling-off' highlights. This leaved me enough flexibility to emphasize or subdue image features as necessary during printing.

Exactly!

vpwphoto · Mar 19, 2011

I just wing it... Happy accidents in the darkroom don't happen when you are all dialed in.

markbarendt · Mar 19, 2011

vpwphoto said:
I just wing it... Happy accidents in the darkroom don't happen when you are all dialed in.

Happy accidents are fun but, there is a question you might want to ask yourself after that happy accident;

"Can I do that again?"

If you are dialed in, the answer is probably yes.

Sal Santamaura · Mar 19, 2011

RalphLambrecht said:
...I make sure to have sufficient active developer to avoid 'rolling-off' highlights...

Aw, come on Ralph, you're undermining the many people who post "I only use 0.01ml* of [insert name of liquid developer concentrate or powder-based developer stock solution here] per roll of film and it works great."

*Exaggeration for effect

nworth · Mar 19, 2011

I just looked up some film data sheets from the 70s and early 80s. The main difference between then and now seems to be an increase in the dynamic range of the films. The useful portion of the curve is up to 3 stops wider. Some films haven't changed that much. Super-XX always had a wide range, as did Royal Pan. Old Tri-X curves look a lot like 320 Tri-X Professional. There is a bit more range on the new films, but in these cases, not a whole lot. Other common films of the period were much more limited, not to mention being grainier and less sharp. Interestingly, development recommendations have not changed. Since the late 50s the manufacturers have recommended development to a gamma of about 0.65. Lately it has been the fashion to develop to significantly lower gammas, however. This seems counterintuitive. It would seem better to develop to a slightly higher gamma and print on a lower contrast grade to get the full range of the modern films.

Photo Engineer · Mar 19, 2011

That is pretty much what I said!

brian steinberger · Mar 19, 2011

It seems to me from PE's graphs that it takes quite a bit of exposure to even reach the shoulder of a film. I guess I'm just confused as to how much of an average stop range there is between the toe and the shoulder. With a normal SBR of 5 stops and properly exposed how close do the highlights come to the shoulder of the film?

RalphLambrecht · Mar 19, 2011

brian steinberger said:
It seems to me from PE's graphs that it takes quite a bit of exposure to even reach the shoulder of a film. I guess I'm just confused as to how much of an average stop range there is between the toe and the shoulder. With a normal SBR of 5 stops and properly exposed how close do the highlights come to the shoulder of the film?

With TMax and a normal SBR of 7 stops, not to worry about.

brian steinberger · Mar 19, 2011

Ralph, so why do shoulders in certain films seem to be an issue if they only come into play above zones VIII or so? Would it only matter for scenes with large subject brightness ranges where highlights can fall up around X and XI?

Also, if you have a highlight that falls on the shoulder of a film and you use N- development will it bring that highlight back down off the curve?

Photo Engineer · Mar 19, 2011

Brian;

I have exposed a 160 speed color negative film from ISO 25 to 400 and gotten good results. The same can be had from any B&W film as well.

PE

markbarendt · Mar 20, 2011

brian steinberger said:
Ralph, so why do shoulders in certain films seem to be an issue if they only come into play above zones VIII or so? Would it only matter for scenes with large subject brightness ranges where highlights can fall up around X and XI?

Also, if you have a highlight that falls on the shoulder of a film and you use N- development will it bring that highlight back down off the curve?

With negative films, where exposure has been "shot to the shadows", even in high SBR scenes, I think the shoulder rarely comes into play with regard to a print.

Paper curves are short in comparison to film curves. Papers are designed to print a "normal" scene's SBR. Probably about what fits in Ralph's "normal" box.

The height of the box in Ralph's diagram is essentially the same as the paper's printable range, from paper white and max black. Simply put the height of the box is all the paper can print.

The right edge of that box is variable, by using n+ development we can move it left to where the contraction curve meets the top of the box or move it right with n- development to where the top of the box would meet the expansion curve.

N- development does keep more highlights off the film shoulder but more importantly it also flattens the whole curve and more SBR naturally prints on the paper.

What PE is getting at is that there is normally lots of extra room on the film's curve. When a 160 film is shot at say 80 or 40 or 25, Ralph's whole normal box can be moved right and up the film's curve to match. Just adjust the base enlarger exposure. Similarly you can move some to the left, shoot that 160 film at 400, but after about a stop the film toe will really start to effect the print quality and shadow detail.

This is all assuming a straight print for clarity. Burning and dodging are the tools we use to get stuff that's on the film curve but, outside the box, onto the paper.

RalphLambrecht · Mar 20, 2011

brian steinberger said:
Ralph, so why do shoulders in certain films seem to be an issue if they only come into play above zones VIII or so? Would it only matter for scenes with large subject brightness ranges where highlights can fall up around X and XI? ...

Mark explained it well already, but in short, yes. Let me also add that some development techniques (stand development as an extreme example) starve the highlights, which causes rolling-off highlights. Not something that works well with long-toed papers in my opinion.

brian steinberger said:
... Also, if you have a highlight that falls on the shoulder of a film and you use N- development will it bring that highlight back down off the curve?

Yes. An N- development basically stretched the characteristic curve horizontally, pushing the shoulder to the right and out of harms way.

brian steinberger · Mar 20, 2011

Wow, I learned something in this thread. Thanks so much guys! It's interesting that some people get so stuck on film curves, with straight line curves and shoulders, etc. It seems that with any film properly exposed and developed you would put the SBR on the straight line of the curve, that film type wouldn't matter, except for maybe some mirco-contrast along the curve. And the toe comes into play with a film much faster without proper exposure then the shoulder does with extreme over-exposure or over development. Am I correct?

RalphLambrecht · Mar 20, 2011

Brian

There is no magic here. It all comes back to:

If in doubt, overexpose and underdevelop.

vpwphoto · Mar 20, 2011

Sure... I use a meter and do write down my times/temp etc for most rolls.
I like Jazz and I do photography that way too....
I used to wrtie down how I made prints but never found that stuff useful years later... Fred Picker ruined photography for me so I went back to my free form ways....

MGIV designed for T-gain films, rumor?

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