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Re: [OM] Feeding the rumor mill

Subject: Re: [OM] Feeding the rumor mill
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 08 Sep 2010 22:18:59 -0400
I have no idea how to create a custom fill or brush in PhotoShop to do 
what you describe but the image size you define for a 5D is 
approximately the same as I'd see 1:1 on my screen.  Tomorrow maybe I'll 
try to do a proportionally sized print of a small cropped section.

Chuck Norcutt


On 9/8/2010 5:49 PM, Ken Norton wrote:
> Well, I've devised a little test. Create an image file--doesn't have
> to be big at all because we're just experimenting around and the
> output can be rather tiny. Create this image file of, say, 300x300
> pixels. Now create a custom fill or brush with alternating black and
> white lines. These lines are one pixel in width.  Follow so far? While
> you are at it, you might as well create a few other squares like this
> with other colors.
>
> What you now have is one or more squares made up of white/black
> one-pixel lines. At 100% on screen they should be perfecty
> sharp-edged.
>
> Now print this at 300 ppi. Examine the print and tell me if you can
> make out the lines. Change resolution to 240 ppi. See the lines?  Keep
> going down until you can make out the lines. Now tell me again that
> you NEED 300 ppi resolution from camera to printer. Most
> printers/inks/papers won't even SUPPORT 300 PPI resolution as there is
> too much bleed.
>
> In the film days you could figure a reasonable enlargement of 8x
> before the image resolution started dropping to the point where
> golden-eyes could see the difference. So, if you figure that a 300ppi
> print is equivalent to a "contact negative", you should be able to use
> a quality scaling tool to upres the photo to the equivalent to 8x
> before the image is hashed up enough to be problematic. But other than
> Genuine Fractiles, most scaling tools aren't anywhere near as good as
> optical enlargement, so chop that 8x in half. 4X is a nice round
> number. And amazingly enough, in my own tests, I've found that 4X
> enlargement from digital files (considering that 300ppi is equivalent
> to a contact negative) seems to be the point where my own eyes detect
> the resolution loss.
>
> Saying the above paragraph another way... Take your image file and
> uprez it 4x. Now when you print this at 300ppi, you're at the
> threshold where print quality, according to those with perfect vision
> will suffer. 8x uprezing is still fine for most general-purpose
> applications.
>
> To bring this full circle, the 5D, when using the 4X factor, allows
> for a print 38.8 inches in height. Inotherwords, you can make a 40x60"
> print that is essentially perfect to everybody except those with
> magnifying glasses.
>
> The 5D's native image height is 2912 which at 300ppi is the equivalent
> to a contact negative print 10x15" in size.  This is why digital has
> passed film in the EFFECTIVE resolution department years ago. Because
> it isn't the capture side that is the limiting factor of output
> resolution, but it's the output side that is the limiting factor of
> output resolution.
>
> Back in the film days there were two reasons to shoot larger formats:
> enlargement and tonal smoothness. With the 5D, the native non-enlarged
> size is already almost 10x15" and tonalities is a non-issue as it
> doesn't change regardless of how big or small you make the print.
>
> AG (do the test, I dare you) Schnozz
-- 
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