[pure-silver] Re: Digital Negatives from Imagesetters
- From: "Tim Rudman" <tim@xxxxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 19 Apr 2006 22:38:54 +0100
Sorry Chris
I just checked your email and see I misread it.
I thought you were talking about copying silver prints.
Must have sped through all the last 2 days posts too quickly tonight.
Tim
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Rudman
Sent: 19 April 2006 22:32
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Digital Negatives from Imagesetters
Hi Chris
Catching up on emails tonight.
Yes I used to use this system years ago when I made a lot of multiple
negative prints but the tonal values were never quite as good I thought.
The advantage of digital negs of course is that the image can also be edited
digitally before making the new master neg.
Tim
http://www.worldbookoflithprinting.com
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Christopher Woodhouse
Sent: 18 April 2006 20:01
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Digital Negatives from Imagesetters
Tim, I think there is a simpler way. It produces better results than any
inkjet negative. Ralph agrees.
You simply photograph a 12x16 inkjet print and print the negative :)
1) If the image has a resolution 600dpi any competent inkjet printer will
give you about 9 lp/mm on paper.
2) A 4x5 negative copy, taken with a standard lens and printed at 12x16
still has a resolution of 7lp/mm on paper (Nikon 150, f11, TriX)
Now here is the clever bit. Use a smooth matt paper. It avoids all the
issues of lighting reflections and so on. In fact, diffuse lighting works
better with matt originals.
You also need to adjust the print tonality for the negative / photo paper
process. I did this very simply:
Make a simple stepwedge in 5%K increments and print it on an inkjet printer,
using whatever method you use to produce accurate prints.
Stick the print to the wall and take an incident light reading. Use the
film's ISO value and add a stop of exposure for good measure. Copy the
picture, using medium or large format (I think 35mm is chancing it) and
develop it at N+1. This gives a negative which will print full range at
grade 2. Make a print of the stepwedge, adjusting contrast and exposure to
get a full range of tones. Compare this print with the inkjet print and make
a conversion table for equal print densities. (You can do this more
accurately with a densitometer). This table becomes a saved photoshop curve.
When you want to make a negative, you first make a proof print on the inkjet
printer and satisfy yourself it is OK, then print it again at 12x16 or
similar, after applying the Photoshop curve. The print will look a little
weird, but when you photograph it and reprint it, will resemble the proof
print, providing you stick to the same exposure, development and printing
conditions.
If the print head is aligned properly (and there are no striations in the
inkjet print), you will only see film grain in the final print, with smooth
gradation in highlight and shadow tones. I had success first time with this
approach and want to sell my shares in Pictorico.
Chris Woodhouse
On 14/4/06 08:40, "Tim Rudman" <tim@xxxxxxxxxxxxxxx> wrote:
> How much does it cost you for an A3 neg Ralph?
> Tim
>
>
> http://www.worldbookoflithprinting.com
>
> -----Original Message-----
> From: pure-silver-bounce@xxxxxxxxxxxxx
> [mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Ralph W.
> Lambrecht
> Sent: 14 April 2006 00:06
> To: PureSilverNew
> Subject: [pure-silver] Re: Digital Negatives from Imagesetters
>
> Sorry to hear about your troubles. I had no such problems. Your
> description sounds a bit odd to me, I'm not even familiar with the
> terms you used (not in combination with halftones and imagesetters
anyway).
>
> Here is how I do it:
>
> 1. Get the image on the screen to your liking.
> 2. Boost or reduce it to 450 dpi at full print size.
> 3. Run the transfer function I supply on my website.
> 4. Invert the image and save it to a CD.
> 5. Take it to the service bureau and ask for a film at 3,600 dpi with
> a 225 line screen, emulsion side up.
>
> Result: a superb halftone, invisible to the naked eye, no banding, no
> mottling, and when contact printed on MG-IV-FB paper, matching the
> screen as much as technically possible.
>
>
>
>
>
> Regards
>
>
>
> Ralph W. Lambrecht
>
> http://www.darkroomagic.com
>
>
>
>
>
>
>
> On 2006-04-14 01:17, "Claudio Bonavolta" <claudio@xxxxxxxxxxxx> wrote:
>
>> Ralph W. Lambrecht a écrit :
>>
>>> To whom it may concern.
>>>
>>> I have reorganized the 'Library' section of my web page. While doing
>>> so, I've added a digital step tablet, a process checker and a
>>> Photoshop transfer function for digital negatives from imagesetters
>>> with
> brief instructions.
>>>
>>> The system work very well and produces high-quality FB prints from
>>> digital files. As always, downloads only for your own private use.
>>>
>>>
>>>
>>>
>>>
>>> Regards
>>>
>>>
>>>
>>> Ralph W. Lambrecht
>>>
>>> http://www.darkroomagic.com
>>>
>>>
>>>
>> Thanks for your contribution Ralph.
>>
>> A couple of weeks ago, I finally found an imagesetter in my area
>> (Geneva
>> - Switzerland), which wasn't that easy because they're all going CTP
>> (Computer-To-Plate) now.
>> So I designed a step tablet in Illustrator (using only the black
>> channel) with a 2% increment between each step and a 1% for the
>> darkest and lightest steps, added a 4000dpi scan of a 35mm TMX film
>> converted to a 8-bits gray scale and a pair of the common USAF1951
>> test target. I then converted it to a negative without applying any
>> curve (the objective was to trace the curve ...).
>> You can find it on http://www.bonavolta.ch/hobby/en/photo/digineg.htm
>>
>> I went to the service bureau, had to re-explain 3 times what I wanted
>> to do (I much better understand why extra-terrestrians avoid any
>> contact with humans) and we finally agreed for an A3 digital neg made
>> with a 20-microns diffusion pattern obtained directly from the AI file.
>> I suppose the 20-microns is the dot size. The finest size they can do
>> is 13-microns and that's probably what I should have asked.
>>
>> I received the neg the next day and printed it around 2:00AM (I
>> couldn't sleep anyway ...).
>> Result is disappointing: contrast is very high but this was expected
>> and can be adjusted, print is really grainy and this isn't the TMX
>> grain, but the worst, because I don't know how to cope with them, are
>> banding and some mottling in uniform areas, already visible on the
> digineg.
>> A pair of articles on how imagesetters work and their features which
>> may explain part of the problems I've had:
>> http://www.exxtra.com/imagesetters/whybetter.html
>> http://www.initpress.ru/eng/stat004.htm
>>
>> I'll try to apply your transfer curve and ask for the maximum
>> resolution but I'm afraid banding and mottling will remain.
>> Finding a good service bureau seems harder than the Graal's quest ...
>>
>> I'll be out for Easter and only be back next Tuesday.
>
>
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--
Regards Chris Woodhouse
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