Do you have a link or reference?
DR5 getting published?
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See the chapter on intensification in Haist's Modern Photographic Processes, volume 2. Among several techniques for intensification of silver images, there's a good discussion on dye based intensification. Leitz formula is discussed and a graph showing density increase is presented.
I don't get all that need and urge for intensification and those sparkling DMax figures.
The same Grant & Haist book cited, on volume 2, section reversal, says that densities beyond 2.2 to 2.4 are useless because the human eye can't discern the difference.
The same Grant & Haist book cited, on volume 2, section reversal, says that densities beyond 2.2 to 2.4 are useless because the human eye can't discern the difference.
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When I used to do it, Id get 2.3 in my standard developer with Delta 100, and around 3.0 with one passed of catechol redeveloper. The difference was very significant to look at, especially side by side.
what about DMin?
You can make an internegative & print that - it's not difficult to get good negs from most BW transparencies. Or print on Harman's Direct Positive Paper.
It's certainly interesting to look at the specified Dmax/ Exposure Scale for most colour transparency films & Agfa Scala in that context - an awful lot of the obsession with Dmax numbers in transparencies seems to be from people with an excessive worry about underexposure latitude/ ability to dig information out of the deep shadows via scanning. And that's before we get on to dealing with the Dmax obsession in photographic paper (and the marketing thereof)...
The scientific consensus on this subject seems to say the same:
https://www.photrio.com/forum/threa...g-but-also-not-die.174178/page-5#post-2268653
https://www.photrio.com/forum/threa...g-but-also-not-die.174178/page-5#post-2268643
But also note that DR5 not only gets astronomically high DMax but also very good dynamic range. This probably means those deep shadows have substantial detail:
https://www.photrio.com/forum/threa...g-but-also-not-die.174178/page-7#post-2269441
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DMax does seem to have psychological effect on the visual experience of slides. However, in this particular case, warm color of slides redeveloped with Catechol also plays a role IMO. Ideally, you would want to compare slides with different DMax but same tint.
And I am saying that if that is what the book says, it isnt correct. dMax beyond 2.4 in transparencies is easily noticeable, its not just a minor difference, it is substantial, and a vast improvement to visual viewing quality of the transparency. 2.4 looks faded when viewed side by side with a high dMax slide, while still being able to simultaneously see the detail in the darkest parts of the slide. If I recall correctly 2.4 if you had a dMin of 0 (which you wont) is only an 8-stop range. The human eye can perceive well beyond 8 stops of brightness range at once. If you couldnt discern beyond a dMax of 2.4 then you would see no contrast and no detail at a dMax beyond 2.4 when looking at a slide (it would simply look black beyond 2.4), and that isnt the case, logically this already should have red flags all over the place - humans can see quite dark areas, and there is the issue of the backlight brightness, increase the brightness of the light behind the transparency and more light will make it through all areas. The statement is patently false.
I am guessing that being a book from the 70s, any tests were made with slide projection, with a very dim low brightness light bulb, which is further compounded by reflections off the projection surface scattered around the room and back onto the surface from the bright areas of the image (assuming the room is even light tight). Home projectors, screens, light bulbs, white walled rooms (and ceiling), reflections and stray light severely limit the blacks you can see. You cant project black, only take away light, and more light would be scattered on the projection surface than would be projected from densest areas of the slides, hence wouldnt be visible.
The tint wouldnt matter, as if you couldnt pick up detail beyond 2.4 you wouldnt be able to see it in the slide warm tone or not. Human eyes are also more sensitive to green than warm tones. Additionally the low light receptors in yours (rods) are monochromatic.
dMax of 2.2 - 2.4 applys to prints not transparencies, where increased density does not translate to increased black or increase optical density due to diffusion and scattering of light as it enters the material, and matte prints are lighter in blacks than glossy etc, you cant really go beyond that in most reflective materials without using something like black 3.0, vantablack, etc.
The difference is also very substantial in colour sldies too, having worked in a lab and processed thousands of rolls of E-6, its quite noticeable when you have an expired roll of slide film thats not suffering too badly but has started to have some base fogging, if its been reduced down to around 2.5 from above 3.0 it looks faded. I saw that with my own rolls when I got a bunch of 10-15 year expired 220 Provia 100f for cheap, still quite good, but faded somewhat, perfectly fine to correct in a scan without issue.
TVs are the same, they project a range of brightness, like a slide would project a range brightness. 0 - 2.4dMax range would be 8 stops, and a contrast of 256:1. A TV would be completely washed out at that contrast ratio, around 500:1 is already considered washed out, and a bad cheap panel. As its a low optical density. A good TV is considered to have a bare minimum of a 3000:1 native contrast ratio, thats brightness range of 11.5 stops, and on a slide it would be a density range of 0 to 3.45. Have you ever looked a HDR TV in person? The minimum standard is 20,000:1, 14.3 stops, or an equivalent of 0 to 4.3d.
I am guessing that being a book from the 70s, any tests were made with slide projection, with a very dim low brightness light bulb, which is further compounded by reflections off the projection surface scattered around the room and back onto the surface from the bright areas of the image (assuming the room is even light tight). Home projectors, screens, light bulbs, white walled rooms (and ceiling), reflections and stray light severely limit the blacks you can see. You cant project black, only take away light, and more light would be scattered on the projection surface than would be projected from densest areas of the slides, hence wouldnt be visible.
The tint wouldnt matter, as if you couldnt pick up detail beyond 2.4 you wouldnt be able to see it in the slide warm tone or not. Human eyes are also more sensitive to green than warm tones. Additionally the low light receptors in yours (rods) are monochromatic.
dMax of 2.2 - 2.4 applys to prints not transparencies, where increased density does not translate to increased black or increase optical density due to diffusion and scattering of light as it enters the material, and matte prints are lighter in blacks than glossy etc, you cant really go beyond that in most reflective materials without using something like black 3.0, vantablack, etc.
The difference is also very substantial in colour sldies too, having worked in a lab and processed thousands of rolls of E-6, its quite noticeable when you have an expired roll of slide film thats not suffering too badly but has started to have some base fogging, if its been reduced down to around 2.5 from above 3.0 it looks faded. I saw that with my own rolls when I got a bunch of 10-15 year expired 220 Provia 100f for cheap, still quite good, but faded somewhat, perfectly fine to correct in a scan without issue.
TVs are the same, they project a range of brightness, like a slide would project a range brightness. 0 - 2.4dMax range would be 8 stops, and a contrast of 256:1. A TV would be completely washed out at that contrast ratio, around 500:1 is already considered washed out, and a bad cheap panel. As its a low optical density. A good TV is considered to have a bare minimum of a 3000:1 native contrast ratio, thats brightness range of 11.5 stops, and on a slide it would be a density range of 0 to 3.45. Have you ever looked a HDR TV in person? The minimum standard is 20,000:1, 14.3 stops, or an equivalent of 0 to 4.3d.
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I cant remember off the top of my head. I made some post on it a long time ago here -
https://www.photrio.com/forum/threads/reversal-processing-of-t-grain-films.124039/#post-1639338
Looks like it barely changed if I wrote that, which makes sense as I remember the contrast greatly increasing, but still being able to view the entire slide. The stain is proportional to the image.
Also looks like I wrote
"edit: I've also done chromium intensifying, and that extra step is not worth it and can give marks and uneven development on the next step regardless of how careful you are for a net of only 0.3 density gain at max, not worth it, you can always rehal bleach and do another staining dev for much greater density gain if you want even higher dmax."
You can check the latest edition of Basic Photographic Processes and Materials:
"Although these films are capable of achieving densities over 3.0, the shadows are best reproduced at densities of 2.7 and less."
For projecting on a white matte surface, in an average sized room that doesnt have black ceiling/walls etc with a regular light source that may be the case. It will have similar limitations to prints (can be improved a lot with a better light source and eliminating reflections). But it doesnt hold a candle to high dMax slides viewed directly. More dMax means more separation between tones, and you can see much more contrast in shadows, and local areas of the images, as the shadows and any other image portion will occupy a broader contrast range on the slide.
Tint does matter while viewing slides. Consider two slides - one tinted and the other untinted but with the same DMax. As the brown stain would cut off most of the green and blue light, the shadows in the tinted slide appear to have more contrast than the shadows in the untinted slide precisely due to the fact that rods are less sensitive to red. Consequently, the warm tinted slide appears less dull than the untinted slide for the same DMax.
True.
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There exists a wikipedia page for Methylene Blue, and the stated prices for this compound suggest, that DR5 used something else.
I don't know what DR5 uses but if he used Methylene Blue he might have imported from China or India. FYI price of Methylene Blue in India is around $12.5/kg:
https://www.indiamart.com/proddetail/methylene-blue-22642660788.html?pos=10&kwd=methylene+blue
His german competitor Wehner (schwarzweissdia.de) to own statement employs a 10bath, 20 steps, 2h process.
I think this about direct vision of the transparency. In our case though it is about a seeing an image reflected off a screen.
No.
The maximum density of the positive
silver image should be at least 2.0, transmitting only 1/100 of the incident light,
or, preferably, around 2.2 to greater than 2.4. High maximum densities are
not needed because, as H. Verkinderen(8) has pointed out, "by normal pro
jection all density-discrimination for densities exceeding from 2.2 to 2.4 is
lost."
(8) H. Verkinderen, "Reversal Processing," Brit. Kinemat., 13 (2): 37 (1948).
https://archive.org/stream/britishki1213brit/britishki1213brit_djvu.txt
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Interesting! What actually causes this loss of information when light is passed through a slide? Has this got something to do with the film base?
Back in the 1970;saround 1973/4 while at University I went to a lecture by a PhD student from the Birmingham School of Photography (part of Birmingham Polytechnic).. His PhD research project was B&W reversal processing and then reversal prints, his print quality was superb.
His main issue was print process time as he was using Ilfobrom, RC/PE papers hadn't been released, washing times between steps needed much longer than films or RC papers. He also indicated that it wasn't easy needing lots of test strips etc. But it can be done.
Ian
Ian: While high DMax and high contrast are absolutely essential for a good viewing experience of slides, they are more a PITA for printing. I did a few reversal prints of slides using SLIMT but it requires good amount of testing. Would you be able to give more details of the process employed by the PhD student? Did he use contrast reduction masks?
It's 46 or 47 years since that lecture, apart from the superb print quality and range of tonality, about all I can remember was he was using Ilford film FP4 in a Leica M2 or M3 and printing on Ilfobrom, oh and his research was sponsored by Kodak Ltd. He wasn't using a contrast mask. I did make some notes at the time but they are long lost.
Ian
Verkinderen was a Gevaert guy...
I shall try to find out what he meant. Thank you for that article.
Found this on DR5 website:
"Archival qualities. dr5chromes are totally archival. More so than the best B&W fiber based prints or negatives."
This rules out the use of dye based intensification.
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