Digital BW, The Print

Martin writes:

> The problem is that the artist generally has
> no control over the viewing distance.

That is often true, but if you follow that line of reasoning, nothing less
than infinite resolution is acceptable.  Unfortunately, infinite resolution
is not achievable.

> People are going to walk right up to that
> 6x6 foot print and view it at 18".

The larger the print, the closer the viewing distance tends to be, if it is
exhibited under identical conditions.  So you really need MF or LF for the
wall-sized prints, if you want to retain detail (although I see a lot of
wall-sized enlargements from 35mm, too).

> I have never heard anyone recommend input to
> an inkjet below about 240 ppi which corresponds
> to 1.5 x 160 ppi. A more common rule of thumb
> is 360 ppi.  Beyond that I cannot detect any
> significant difference but others report
> that they do see a difference by going to
> 720 dpi.

In theory there is always a difference for higher resolutions.  In practice,
the visible difference improves in a rapidly diminishing fashion with
increasing resolution, such that 1.5x is usually the cost-effective choice,
2x on rare occasions.  But it is largely pointless for photographers to try
to get 360 ppi to print on a 160 ppi printer.  They'd be far better off
going to 240 ppi and finding a printer that can output 200 ppi.

> For myself I would like the image quality of my
> inkjet prints to be equal to my silver fiber
> prints and this seems to require 360 ppi to the
> printer regardless of print size. Since the
> largest I can print with my 1280 is 13x19 this
> leads me to a minimum file size of about 30
> megapixels or if I want my file to be capable
> of being printed at 20x24 about 60 megapixels.

So you work exclusively in medium format and beyond, right?  You won't get
resolutions like that from 35mm, as a general rule.

I like to have the highest possible resolution, too, but the reality is that
it usually doesn't matter that much.  If it did, digital would not be as
popular as it is today.