Has anyone done any LVT negatives?

[leicaglow]

<p>I'm trying to refine my print quality of image to 40" prints, and was going to experiment with DR5's conversion of digital images to a negative. What I want to do is take medium and large format drum scans, manipulate them in PhotoShop, then put them back onto film via their LVT process so I can do Silver Gelatin prints. Has anyone used LVT before? I'm most interested in the quality of the resulting negative, and if there are any artifacts put back onto the negative. And also, whether I should put the MF LVT onto a larger film material, like 4x5. I've used CRT processing and wasn't very happy with it, and frankly I'm not even sure how LVT differs from CRT. Thanks for any real world experiences.</p>

[jtk]

<p>Are you aware that Durst and DeVere make digital enlargers that print directly to gelatin silver? Conversion of digital to anything else is inherently lossy ... I can't envision an advantage to introducing a film internegative. In case you've not looked closely lately, inkjet printers papers are now exquisitely close to the best of gelatin silver in some respects, vastly superior to gelatin silver in the rest.</p>

 

[dave_redmann]

<p>That sounds like a lot of trouble when you could just get A&I, Elevator Digital, or any one of several other places to print your digital files directly onto fiber-based, silver-halide paper using a modified Lightjet or whatever. It's not cheap ($40 - $50 for an 8x10 and up from there), but I can't imagine that what you're talking about is cheap, either.</p>

 

[silverpixel]

<p>The LVT's used a tightly focused LED light source to generate images up to RES 120 (lines per milimeter) on film mounted in a spinning drum - think of a drum scanner flowing backwards. Most were limited to a max size of 8x10" but I believe one could do 16x20". Back in its day it was highly regarded among film recorders for image quality, since true photographic output options were few, and CRT based film recorders were limited in resolution by inherent phosphor blooming, where bright dots on the exposing screen become blurs instead. Then laser-based imagers were introduced that were at least as sharp, faster by virtue of their higher light output, and able to expose paper directly, so in spite of a precipitous drop in price, film recorders in general vanished from the market nearly overnight, having become obsolete for their original audience. They can now be had for under a penny on the original dollar and even seem like a reasonable output option for private use, but not for the faint at heart - long learning curve, fickle electronics, and prohibitively expensive parts. Heavy duty power conditioning is required to avoid banding or rasterization artifacts.</p>

<p>I had fun experimenting with LVT output as contact negatives for alternative processes. When the machine was running well, which wasn't as often as I wished, there were often no visible artifacts and the sharpness was quite good, although not what the specs led me to expect. There was a certain softness that didn't matter too much for contact printing. The top exposure was a bit weak, and a decent Dmax depended on tweaking chemical time and temperature.</p>

<p>Dave is right in pointing out that if your final product is a standard silver gelatin print, direct-to-paper is far superior. Not only is it faster and cheaper, the additional step introduces huge control (read calibration) problems with unneeded variables. And an LVT negative is likely to be twice as expensive before you even get to the darkroom.</p>

<p>The digital enlarging heads are OK for some work, but for ultimate sharpness they come up short. The imaging unit has far lower resolution than a laser imager, and the image travels through a lens after the DA conversion, introducing falloff in both intensity and sharpness. Why include optical aberrations unless you had to? The Lambda and LighJets used by the labs mentioned above print at RES 12 or RES 16 which is plenty for large format prints.</p>

<p>If you want the ultimate sharpness and quality in B&W, RES 160 exposure on 11x14" fiber silver gelatin is my new product. Resolution is 10 times higher than LightJet or Lambda. Dmax is over 2.30 and the exposure dot size is smaller than the paper grain. The overkill on exposing resolution ensures absolute freedom from artifacts, archival processing gives proven durability, and the images have the look and feel collectors, artists, and public prefer. Drum exposure ensures evenness across the entire print.</p>

<p>While I have nothing against new technology (obviously) and have seen beautiful inkjet prints, I have to disagree with John on two points - it is analog to digital conversion that is inherently lossy, and there is no inkjet (or other) print I'm aware of that comes close in any respect to mine. Of course, since I've not yet marketed the prints openly, no one could be blamed for not knowing this. Time to change all that.</p>

<p>In fact, I CHALLENGE ANYONE to beat my digital fiber prints in a real life test, with any technology you like.</p>

<p>Contact me if you'd like more information or a sample.</p>

[dave_redmann]

<p>Mike, are you the person who previously posted about having built your own machine to print digital files onto silver halide paper? I always meant to follow up on that post, but somehow lost it. I'm intrigued by your claims on several fronts, if you don't mind humoring my questions.</p>

<p>I assume that garden-variety Fuji Frontiers and the like are, to use your terminology, for the most part actually RES 12 or RES 10 (I'd be surprised if Fuji and Noritsu make things with even dimensions in British units, e.g. 300 or 250 ppi, instead of metric ones, e.g. RES 12/304.8 ppi or RES 10/254 ppi). But some of the existing places that print digital files to FB paper claim 400 ppi (probably really RES 16 / 406.4 ppi). Do you really mean your printer is RES 160, not RES 16 (given the comment "Resolution is 10 times higher than LightJet or Lambda. ")? And if so, presumably the source file for that 11x14 you mention would have to be about 2.5 <strong>giga</strong>pixels? That would be welll over 100 lp/mm even from 8x10 sheet film, and I wonder what sort of computer you'd need to edit it? Or is yours not a continuous-tone process, using 4000 dpi to achieve some lower number of ppi, similar to an inkjet?</p>

<p>I've had some prints professionally made on FB paper with a digital enlarger (the Durst I think), but was not exactly bowled over (although to be fair, these prints cost about half of what most places charge to print FB with a Lightjet). Mostly I stick to cheaper prints, but every now and then I get high-end ones. It's good to know what the best looks like, so you know what to shoot for / hope for, given your day-to-day constraints.</p>

<p>Thanks for any info.</p>

 

[silverpixel]

<p>Hi Dave, that's some memory for a post almost a year old! Personal issues have kept me from starting full work on the market side of this project but I'm confident that the website and lab will be operational in the US within a month.</p>

<p>I'd be glad to answer any questions, within the limits imposed by the need to protect a marketable "secret". The DPI and RES ratings for consumer-oriented equipment are unfortunately rather meaningless. The perception of sharpness is a complex psychological phenomenon and manufacturers have mostly resorted to claiming "apparent" resolution, since a flat spatial frequency figure ignores other even more important variables such as fixed vs. variable dot size, the geometry and sharpness of the dot itself, number of shades or inks or bit depth, patterned or randomized distribution of dots, sharpness loss and recovery in the RIP and printing head...the list goes on and on. In the case of Fuji Frontier and Noritsu minilabs, they rate optimistically in DPI and who am I to say the math is questionable if the consumer likes the product?</p>

<p>My machine has addressability at RES 160 (no typo) with an effective exposing dot size averaging 6 microns, depending on the intensity of the laser beam for each pixel. It is certainly overkill since Galerie stock can't come close to resolving it, but that ensures any artifacts are below the grain/emulsion scatter threshold. In practice I find that a good 600MB file upscaled in my RIP is quite hard to distinguish from a full resolution file even with a good loupe, and even my 6MP files from a D70s look decent. I don't have computer hardware capable of editing a full page image at RES 160 and 16 bit depth, so I've used small prints for testing at that level, realizing the impracticality but wanting to see the possibilities.</p>

<p>The laser dot on the paper surface has a diffuse edge falling off appreciably from about 60% of radius, so I think it's fair to say that even with 8 bits the process is continuous tone up to full resolution. Again, the limits imposed by scatter within the emulsion and the size of paper grain are the real limits. Theoretically this means to me that the full capacity of the material to render sharpness is utilized, so if the file is good, there really is no chance of making a sharper print with silver gelatin paper, regardless of exposure method.</p>

<p>Some inkjet printers use variable dot size coupled with multiple inks at very high resolution to simulate continuous tone very effectively and I've seen outstanding prints. My current size limit of 11x14" certainly is a point against me, but will be easily overcome if the project flies. Back at the math, though, since my printer also varies dot size and uses a 16 bit palette at close to 4000 dpi, when an inkjet can use 65,535 vials simultaneously at those same parameters, we ought to have a contest, which the inkjet may win if the manufacturers can make dot size the same as drop size by that time. And yet, some of us diehards may continue to prefer the look and feel of silver gelatin fiber even then. Time will tell.</p>

<p>The whole point I was after was to smear the divide between digital and wet photography so we can reach for the tool of choice without having to accept the accompanying limitations on print medium down the line. Now I can shoot film or digital, process in my image editor, and output to whatever I see fit with no regrets. My prints take over half an hour to expose and I process by hand with old fashioned archival wash, so they aren't cheap, but I've yet to find anyone dissatisfied with the results.</p>

<p>So, I stand by my boast and invite anyone to a shootout. For more information or to arrange to see a sample, or even to discuss theory and practice in this area, everyone is welcome to contact me. I look forward to it and wish the best to all.</p>

[dave_redmann]

<p>Your most recent post raises (I think) an even more fundamental issue, which I'll raise, then contact you privately.</p>

<p>Are silver halide photographic materials really continuous tone? Given the limits of human vision, it probably doesn't matter. Nevertheless, I tend to think that the answer is no, but then maybe nothing except dye-based film and paper is, and only then when exposed and printed in entirely with analog equipment, and only within a certain gamut.</p>

 

[silverpixel]

<p>You are absolutely right, David, in that continuous tone as understood in the realm of light as wave doesn't translate to print in any common medium, as all prints contain discrete image elements, whether grain or dye, which are either on or off - so ultimately all photographic images are in fact digital, clipping the intermediate analog values. It happens from capture regardless of technology, gets diffused in optical or electronic transform recovering some of the <strong><em>appearance</em> </strong> of continuous tone, which is what commonly refers to in a print.</p>

<p>So you are again right in that perception has the final say in defining continuous tone. Resolution beyond the limits of our senses lets us comfortably ignore the data lost in conversion to digital. If gradations seem smooth and artifact free at a given distance or magnification, we can call it a rose if we like, but there is not yet a standard for how closely we should look. Meaning evolves. Chomsky's E-language at work.</p>

<p>I must mention one curious exception I'm aware of, briefly described in the book "Color Photographic Printing" where IIRC a tank of ionized mercury is used to reproduce an optical interference pattern yielding true continuous tone, matching the projected image wavelength for wavelength at each atom. The image isn't permanent but it must be the ultimate print!</p>

[leicaglow]

<p>Well, Durst is now "under", but my goal was to do this process: MF and LF -> drum scan -> PhotoShop -> LVT -> Silver Gelatin print. My intention is to control the dodge and burn process in PS, so that a virtually straight print could be made on silver gelatin. It's for a fairly large edition where manipulation is rather difficult for that many prints, and where collectors are demanding silver prints.</p>