[alt-photo] Re: New Platinum Prints

[Tom Kershaw]

Loris,

Is it your view then that a printer such as the Epson 3880 provides
sufficient resolution for digital negatives, including higher definition
processes, e.g. cyanotype or carbon transfer?

My previous experiments have been with the Epson 2100/2200, a printer
that shows significant banding, especially in areas of more uniform
tonality. - I checked with Sandy King and he had experienced this issue
with the Epson 2200 as well.

Tom

Loris Medici wrote:
> Further clarification:
>
> Errr, 2000 ppi!? That's too much I think; 18 lines per mm (l/mm) is roughly
> equivalent to (only) 460 ppi. (Which is very very good in fact!)
>
> In case of halftone printing, you'll need 460 (screen) x 16 = 7360 dpi
> hardware resolution (for being able to print all 256 tones), and a file
> resolution of *920 ppi* (because you need a file with 2x resolution of the
> screen, for optimum results in conversion from grayscale to bitmap), to be
> able to hit the resolution limit of the process/paper combination mentioned
> above.
>
> For other output methods, you'll be all right with a hardware that is able
> to print at *460 ppi*... (IIRC, some Lambda printers can achieve 400 ppi.)
>
> OTOH, as I previously wrote in my reply to Christina, that much print
> resolution is pretty unnecessary, since even someone with perfect 20/20 eye
> sight / visual acuity won't be able to resolve something more than 13-14
> l/mm at 10" (minimum comfortable) viewing distance, w/o the aid of a loupe.
> Plus, practical viewing conditions are almost always farther away than 10",
> therefore something significantly lower than 13-14 l/mm still does the job.
> E.g. real life experience with inkjet prints / digital negatives; ~ 7-8 l/mm
> in my case. (I don't even mention lighting conditions BTW; I just assume
> perfect / ideal lighting instead - which is a whole other issue...)
>
> Regards,
> Loris.
>
>
> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org On Behalf Of
> etienne garbaux
> Sent: Tuesday, April 13, 2010 6:55 AM
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: New Platinum Prints
>
> ...
>
> Using silver-based test negatives, I can resolve about 18 
> lpmm with Pt on hot-pressed paper, and over 20 on baryta-coated 
> paper.  Both will show the dither pattern on any inkjet negatives 
> I've seen (as well as the raster pattern from imagesetter 
> negatives).  I estimate that we need file and printer hardware 
> resolutions of 2000 ppi or so to eliminate it (80 Mp for a 4x5" print).
>
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