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03/09/2011 11:46:05 PM · #26 |
Originally posted by Spork99:
With B&W film, it's possible to greatly manipulate the contrast curve way beyond what digital can record in one shot. Now, to do things like this requires an in-depth understanding of the scene, the film and special development techniques that use a waterbath. I've personally made images where on a straight print it was possible to read the printing on a lit 100W bulb and show detail inside of a dark closet across the room...a dynamic range well in excess of what the eye could see and certainly more than 3 stops of what film could normally record.
Very long exposures were required and the film's reciprocity failure only aggravated this. I recall leaving the shutter open for hours at a time for this kind of work.
The process would not work for color film because each color has a different emulsion layer, each layer has a different reciprocity curve and develops at a different rate. |
This is all true. Relatively low-ISO B/W materials (50, 100, some of the 200s) hold the possibility of extraordinary dynamic range and visual acuity both. This is the heart of Zone System. When B/W negatives are developed, the dark (thin) areas reach the full potential of their development early on in the process, but the bright (thick) areas continue to develop for a considerable length of time beyond what would be considered nominal for the given film/developer combination.
Accordingly, it is possible to both expand and contract the tonal range of these films by carefully monitoring exposure and processing times. The basic rule is to 'expose for the shadows' (i.e. make sure the shadow areas where you want to preserve detail are adequately exposed to contain that detail) and then 'process for the highlights' (i.e. determine if you need to expand the tonal range/contrast [push processing] or compress it [pull processing], and by how much.
As Spork pointed out, this was never possible with color film because of the several emulsion layers involved.
For all practical purposes, HDR imaging and/or tone mapping is the digital equivalent of Zone System. The purest example of this is actually not in the more-obvious compression-of-tonal-range that most people associate with HDR imaging, but rather the expansion of it: compare the before and after of this image.
 
This was a 3-image HDR composite that was created to expand the tonal range of the shot to something closer to what the eye was perceiving. Essentially the same thing could be accomplished with HDR Efex Pro's single-image tone mapping, but the Photomatix of that time didn't handle this as well without the merge. Topaz Detail also can do this well; it's a kick-ass tone mapping program in its own right. It's all about the manipulation of local area contrast.
R. |
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03/10/2011 08:36:32 AM · #27 |
Originally posted by Bear_Music:
Originally posted by Spork99:
With B&W film, it's possible to greatly manipulate the contrast curve way beyond what digital can record in one shot. Now, to do things like this requires an in-depth understanding of the scene, the film and special development techniques that use a waterbath. I've personally made images where on a straight print it was possible to read the printing on a lit 100W bulb and show detail inside of a dark closet across the room...a dynamic range well in excess of what the eye could see and certainly more than 3 stops of what film could normally record.
Very long exposures were required and the film's reciprocity failure only aggravated this. I recall leaving the shutter open for hours at a time for this kind of work.
The process would not work for color film because each color has a different emulsion layer, each layer has a different reciprocity curve and develops at a different rate. |
This is all true. Relatively low-ISO B/W materials (50, 100, some of the 200s) hold the possibility of extraordinary dynamic range and visual acuity both. This is the heart of Zone System. When B/W negatives are developed, the dark (thin) areas reach the full potential of their development early on in the process, but the bright (thick) areas continue to develop for a considerable length of time beyond what would be considered nominal for the given film/developer combination.
Accordingly, it is possible to both expand and contract the tonal range of these films by carefully monitoring exposure and processing times. The basic rule is to 'expose for the shadows' (i.e. make sure the shadow areas where you want to preserve detail are adequately exposed to contain that detail) and then 'process for the highlights' (i.e. determine if you need to expand the tonal range/contrast [push processing] or compress it [pull processing], and by how much.
As Spork pointed out, this was never possible with color film because of the several emulsion layers involved.
For all practical purposes, HDR imaging and/or tone mapping is the digital equivalent of Zone System. The purest example of this is actually not in the more-obvious compression-of-tonal-range that most people associate with HDR imaging, but rather the expansion of it: compare the before and after of this image.
This was a 3-image HDR composite that was created to expand the tonal range of the shot to something closer to what the eye was perceiving. Essentially the same thing could be accomplished with HDR Efex Pro's single-image tone mapping, but the Photomatix of that time didn't handle this as well without the merge. Topaz Detail also can do this well; it's a kick-ass tone mapping program in its own right. It's all about the manipulation of local area contrast.
R. |
I knew these guys could explain it better than me! ;-)
Robert's always been the go to guy for HDR chops around here. |
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03/10/2011 11:34:28 AM · #28 |
Originally posted by Bear_Music:
Originally posted by Spork99:
With B&W film, it's possible to greatly manipulate the contrast curve way beyond what digital can record in one shot. Now, to do things like this requires an in-depth understanding of the scene, the film and special development techniques that use a waterbath. I've personally made images where on a straight print it was possible to read the printing on a lit 100W bulb and show detail inside of a dark closet across the room...a dynamic range well in excess of what the eye could see and certainly more than 3 stops of what film could normally record.
Very long exposures were required and the film's reciprocity failure only aggravated this. I recall leaving the shutter open for hours at a time for this kind of work.
The process would not work for color film because each color has a different emulsion layer, each layer has a different reciprocity curve and develops at a different rate. |
This is all true. Relatively low-ISO B/W materials (50, 100, some of the 200s) hold the possibility of extraordinary dynamic range and visual acuity both. This is the heart of Zone System. When B/W negatives are developed, the dark (thin) areas reach the full potential of their development early on in the process, but the bright (thick) areas continue to develop for a considerable length of time beyond what would be considered nominal for the given film/developer combination.
Accordingly, it is possible to both expand and contract the tonal range of these films by carefully monitoring exposure and processing times. The basic rule is to 'expose for the shadows' (i.e. make sure the shadow areas where you want to preserve detail are adequately exposed to contain that detail) and then 'process for the highlights' (i.e. determine if you need to expand the tonal range/contrast [push processing] or compress it [pull processing], and by how much.
As Spork pointed out, this was never possible with color film because of the several emulsion layers involved.
For all practical purposes, HDR imaging and/or tone mapping is the digital equivalent of Zone System. The purest example of this is actually not in the more-obvious compression-of-tonal-range that most people associate with HDR imaging, but rather the expansion of it: compare the before and after of this image.
This was a 3-image HDR composite that was created to expand the tonal range of the shot to something closer to what the eye was perceiving. Essentially the same thing could be accomplished with HDR Efex Pro's single-image tone mapping, but the Photomatix of that time didn't handle this as well without the merge. Topaz Detail also can do this well; it's a kick-ass tone mapping program in its own right. It's all about the manipulation of local area contrast.
R. |
I recall using Super XX, PlusX and later, TMax100 sheet film, all of which I spent hours creating an understanding how to manipulate their contrast curves by shooting and processing calibrated grayscale targets and measuring the results using a densitometer...essential, but B O R I N G.
From looking at some of my notes, development times for the most extreme cases might be extended to 30-40 minutes, alternating between developer and a waterbath. The key was no agitation in the waterbath. While the developer in the highlighs was quickly exhausted, the developer in the shadow areas would continue to work while the film was in the waterbath. |
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03/10/2011 02:17:55 PM · #29 |
Originally posted by Spork99:
I recall using Super XX, PlusX and later, TMax100 sheet film, all of which I spent hours creating an understanding how to manipulate their contrast curves by shooting and processing calibrated grayscale targets and measuring the results using a densitometer...essential, but B O R I N G.
From looking at some of my notes, development times for the most extreme cases might be extended to 30-40 minutes, alternating between developer and a waterbath. The key was no agitation in the waterbath. While the developer in the highlighs was quickly exhausted, the developer in the shadow areas would continue to work while the film was in the waterbath. |
Good times, good times. ;-)
Message edited by author 2011-03-10 14:18:02. |
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