LVT questions

[Pieter]

I tried posting this on Photo and got no response. Maybe I'll do better here.

I am considering trying to make some optical enlargements from black and white digital originals. Assuming I have 4x5 LVT (actually 4x4, images are square) negatives made, how big can I print them? I don't think I would go more than 20x20. The originals are 10x10 @ 300dpi, about 8.5 MB. I have had them printed digitally at 20x20 and they look fine (all dimensions are inches).

Also, can anyone recommend a supplier for the LVTs? I am in SoCal, but I assume any source in the continental U.S. would do.

[Pere Casals]

Hello Pieter,

In this case the LVT 4x5" negative outresolves your originals (has way more pixels), so what will limit the enlargements is your sourced file, the LVT 4x5 resolves way more, and the LVT can also make 8x10" resolving crazy more.

If your images doesn't have the resolving power then LVT won't solve it. Your originals won't allow top notch quality at 20", but if you are happy with your 20" proofs then the LVT won't limit the quality for this job.


http://www.prepressexpress.com/pages.../rhinofaq.html


LVTs print at RES40 and at RES80, this is in pix/mm


(Click to enlarge)

Note that you have 3000 pix wide in your originals and the LVT has 8,128 Pix in the 4" short side. You have to blow 3000 into 8,128, you may use dedicated image blow up software to improve your result, this requires a wise job.


The size you can print from a LVT 4x5" negative (if having the right digital file) depends on the print quality you want at reading distance. At "normal" viewing distance (we see the whole print) you need some "true" 60Mpix total to outresolve a human eye that's moving the eye sight over the print. A human eye sees some 8Mpix but most is concentred in the fovea, by not moving the head but moving the eye then the 60MPix can be explored.


Let's consider you want a print that is "Graphic Arts" perfect at reading distance, then you may want 300Pix per inch, PPI.

Note that DPI is different than PPI, PPI (pixels) are continous tone and dots are not, you may need many Dots in a Pix, 400PPI may need 4000DPI...

As you have squared images then you have 8,128 Pix in the 4" short side (RES80 LVT quality), so 8,128Pix/300 = 27" for the short side, or 34" print from a full 4x5" negative, 64" print from a 8x10" negative.

300PPI are (300/25) 12 pix/mm, so 6Lp/mm (line pairs per mm), so mostly outresolving the eye, so total quality.

In practice if digital file is big/sharp and if it was processed with wisdom with the right acutance, and with the right algorithms, then you may go beyond those 27", but these is a personal choice, 27" will be standard top graphic quality, if you enlarge more then you are under 300PPI, ...but a big print at 150PPI may look nice.


Let me point that the amazing Sebastião Salgado's Genesis exhibition had many optic enlargements from 4x5 (Ilford Delta 100) LVT printed negatives for the digital shots he took after 2007, they placed 4 images in each 8x10 Delta 100 sheet. Pre 2007 shots were Kodak TXP crafted with a Pentax 645. It was a challenge to make the digital material look like TXP, they did a top notch job. Prints were very big, not perfect at reading distance, of course this were monster prints from 645/dslr (several detractors around don't understand that job... ), but still the prints were impressive, the most impressive photo work in this century was (partially) crafted with a LVT Rihno.

If wanting even bigger prints it is possible to print 8x10" with LVT, for squared it would be 8x8", or between 6x6" - 7x7" to fit in a 5x7" enlarger like a Durst 138, not requiring a 8x10" monster enlarger.

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Also it has to be pointed that the optical enlargement of the LVT negative won't have a noticeable loss of quality, a good 4x5" enlarger lens (in the hands of a good printer) will well outresolve the negative, so all quality you have in the LVT negative will be crafted on the print.

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I'm in the EU, I don't know LVT services in the USA, but there are several still working, at least a good one in NY, IIRC.

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You have another choice, this is printing photopaper with a Lightjet/Lambda. A member here (Bob Carnie) prints even on FB photopaper with a Lambda, you may contact him.

[Pieter]

Hello Pieter,

In this case the LVT 4x5" negative outresolves your originals (has way more pixels), so what will limit the enlargements is your sourced file, the LVT 4x5 resolves way more, and the LVT can also make 8x10" resolving crazy more.

If your images doesn't have the resolving power then LVT won't solve it. Your originals won't allow top notch quality at 20", but if you are happy with your 20" proofs then the LVT won't limit the quality for this job.

Pere,

Looking at the site you included in your post, it seems like I might be best off making 2-1/4x2-1/4 files and ganging them up on an 8x10 LVT with no loss of resolution. I can then slice the negative into strips and treat it like 120 film, an easy solution for me. Thanks again.

Pieter

[Pfsor]

Thank you, Pere, for the time and effort you put into your answer. You're a real asset to this forum. Cheers!

[Tin Can]

Good work Pere.

Who has the LVT's?

Anywhere in the world. if you know.

[bob carnie]

Good work Pere.

Who has the LVT's?

Anywhere in the world. if you know.

There is one in New York that my friends have used with good results.. sorry no name but if it comes to me I will post... He was a member on this site btw , some old threads have his name and info I believe

[Pere Casals]

Who has the LVT's?

Anywhere in the world. if you know.

Randy, LVTs are a bit hidden

This is in Sacramento, California: http://www.coxblackandwhitelab.com/?page_id=211

The cost:

4×5 b/w Negative: $35.00,
8×10 b/w Negative: $70.00

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I would point a good printer using LVTs , a prominent "Tireur" in this case (French), this is Dominique Granier: https://dominique-granier.book.fr/

He offers converting digital negatives in 4x5 sheet film with the LVT and then making prints. He takes a TIFF with 2.2 Gamma and he makes the negative for customers. https://dominique-granier.book.fr/ne...hier-numerique

He is in Paris...

Granier made Salagado's reference prints and also the prints for collectors... not a bare "amateur" I'd say...



Another "connoisseur" is Philippe Bachelier, the man that was developing Salgado's TXP, with Calbe 47 (later Atomal 47), to make it work like TX:



Taschen made a nice book with all that...


I post their portraits because (IMHO) their eyes tell the way they work.

[Tin Can]

I have looked at this site many times over the years.

https://www.albumenworks.com/digital.../archival.html

[Pieter]

Thank you Pere. A most comprehensive overview of the process. Now I need a source--Chicago Albumen Works looks promising. Also Cox Black and white lab here in California. I'm going to add a grey step scale to unused area of the image--any good sources for a digital step wedge? Or just create it from scratch in PhotoShop or Illustrator?

[Pere Casals]

grey step scale

The LVT film recording can be customized, but result depends on film, on development and the curve they apply to translate pixel gray levels to exposure.

You will need to contact the Lab to get instructions about how you should adjust the pixel gray levels to get the densities you want. Perhaps you may say that you want a certain density level for a certain digital gray level, but probably it's straighter that they tell you how their standard process work and then you adapt yours files, probably this will be the cheapest way. Perhaps they have an easy recipe...

Once you get their "process calibration" for a film they use often, you may order a 4x5 negative with a mosaic of small a images in it, say 9 images of the same picture but with different gamma adjustments or contrast. You have to learn to design the negative to be workable with a mid contrast grade for the paper, but also you may need to adjust the gamma in your digital file to have a pleasing image.

In your paper printing process you may easily adjust the contrast, but you will be tied to the gamma interpretation, so perhaps it's more important that you nail the gamma than nailing the contrast.

Perhaps they have ICC profiles that will allow to see in the monitor a software proofing of possible prints... you have to ask them.

Just ask how they work, adapt to their particular way, ask if they use a particular ICC for proofing what the negative would do with a certain paper grade, and order a mosaic of around 35mm format images with diverse gamma/contrast to find the sweet point.
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Regarding the recorded image size on film you also should also experiment, you know how many pixels they place in an inch, so you have to decide how many LVT pixels you want in an inch of your print, 300 is an excellent number, I'd say, but you may experiement by enlargind a crop more or less.

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...so you have to experiment in two ways, the gamma/contrast in the digital file and the image size in the recorded film, this will tell you first hand what will suit your taste. IMHO there are no standard rules for that.