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DPI,Megapixels and print size

 
 
OL'Hippie
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      02-21-2006
Although I am not new to digital cameras I am new to printing LARGE
prints. So my question is this, with a 6 Megapixil camera shooting at
2816 x 2112 (HQ) what can I expect to be the maximum print size, before
loosing clarity? I know TIFF and RAW are better but unfortunately my
best pics are at 2816 x 2112 so any help would be appreciated.
Bruce

 
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James Silverton
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      02-21-2006
OL'Hippie wrote on 21 Feb 2006 08:13:25 -0800:

OH> Although I am not new to digital cameras I am new to
OH> printing LARGE prints. So my question is this, with a 6
OH> Megapixil camera shooting at 2816 x 2112 (HQ) what can I
OH> expect to be the maximum print size, before loosing
OH> clarity? I know TIFF and RAW are better but unfortunately
OH> my best pics are at 2816 x 2112 so any help would be
OH> appreciated. Bruce

If you are not cropping, you only need divide the pixel count by
the dpi desired. With 2816x2112, that would be about 15x11
inches at 180dpi. Given that the viewing distance might be
somewhat greater, you might use 150dpi or even less for a larger
picture.

James Silverton.

 
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tomm42
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      02-21-2006

OL'Hippie wrote:
> Although I am not new to digital cameras I am new to printing LARGE
> prints. So my question is this, with a 6 Megapixil camera shooting at
> 2816 x 2112 (HQ) what can I expect to be the maximum print size, before
> loosing clarity? I know TIFF and RAW are better but unfortunately my
> best pics are at 2816 x 2112 so any help would be appreciated.
> Bruce


Depends on a lot of things:
1. Are you a get your nose in a picture to check sharpness kind of
photographer, in that case 8x10 or 11x14 with a good lens is your
answer.
2. Do you have the kit lens for your camera? See above.
3. Do you like size better than extreme sharpness and have good lenses,
then you can approach 20x30 and still have a good looking print, keep
your nose a couple of feet away.

When I was printing for a photographer we would routinely do 20x30
portraits from a 6mp Kodak DCS760, 50 f2 or 80-200 f2.8 lenses were
generally used, looked very good, a lot of folks couldn't believe the
quality we were getting. The trick with digital is that while digital
prints struggle to compete with photochemical prints in small sizes,
say up to 8x10 or 11x14, they go big much better, as long as the person
handling the file knows what to do. Film from a 35mm camera just starts
to break down after 11x14, while digital may not be nose on the print
sharp at big sizes a well done photo does look very good.

Tom

 
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All Things Mopar
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      02-21-2006
Today OL'Hippie commented courteously on the subject at hand

> Although I am not new to digital cameras I am new to
> printing LARGE prints. So my question is this, with a 6
> Megapixil camera shooting at 2816 x 2112 (HQ) what can I
> expect to be the maximum print size, before loosing
> clarity? I know TIFF and RAW are better but unfortunately
> my best pics are at 2816 x 2112 so any help would be
> appreciated. Bruce
>

Prevailing wisdom says you need a minimum of 200 PPI (Pixels
Per Inch, it isn't DPI) for a good print, preferably 300 PPI.
But, the definition of "good" depends on a number of other
factors such as subject type, lighting, exposure, extent of
noise or banding in the original image, etc.

But, the most important discrimator is what /you/ think
"good" means.

Others considerations include the paper type, glossy looks
much different than matte, print techology type, and viewing
distance. People view a 4x6 from just a short distance, an
8x10 no closer than arm's length, but usually on a wall or in
a tabletop frame. 11x14 and 16x20 are most often viewed on
walls from 4-6 feet away.

I have found that if you use high quality paper, have a good
print (or use a good service), and keep viewing distances
reasonable, you can do well at 150 PPI or less. I have gotten
good results with as little as 70 PPI onto Super B 13x19
paper, but I don't view them closer than 5 feet.

So, as another person commented on, pic a PPI you want to
maintain and simply divide one dimension of your image to get
the max size. But, and this is very important, run a test
print and just take a look. If you're doing this at home, that
chews up some ink and one sheet of paper.

As to format of the image, that's all hooey. It doesn't matter
if it is saved as lossless TIFF or lossy JPEG /IF/ the
underlying pixel map is correct and, in the case of JPEG,
you've kept compression to a minimum consistant with the file
size you can stand. I know of know one who saves their final
image back to RAW but many use a proprietary format from their
fav graphics editor to maintain layers, vectors, and other
things in full-size, then create a print-only file in
something that will maintain the image integrity.

If you tell us something about the kinds of pictures you
shoot, I may be able to elaborate more on what you perceive
the challenges to be and what your expectations of quality
are.

Good luck.

--
ATM, aka Jerry
 
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OL'Hippie
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      02-21-2006
Wow, Now my head is really spinning LOL Thank you all, I think that I
will invite you all to go see some of my pics I have them posted on
Fotki, the reason I am asking is that I have the opprotunity to sell
several of my photos matted and framed to a designer that is doing a
job locally and they like what they have seen of my work and it is all
local photos soooooooo. Come take a look I believe all of them can be
viewed at the original upload size but I will recheck that to be sure.
Here is the page http://public.fotki.com/goldbeach/

The photos I am most interested in printing large are in the albums
"Gold Beach & Vicinity" , "Final Sunset 2005" and "Charleston Harbor"
and "Otter Point" other than that all were taken with the same
resolution although some are from a 4 megapixil camera.

Thank you all so much and I believe I will be a regular here from now
on !!
Bruce-n-Gold Beach

 
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OL'Hippie
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      02-22-2006
Hi Tom,
The lens I have on the camera came with it, I guess I should have told
you folks what I was using it is an Olympus sp-500UZ and the 4
megapixil camera is the Olympus UZ-750. I only bought the extension and
a UV haze filter for the UZ-750, but I also bought a polarizing filter
for the sp-500. I am still trying to get my technique down with these
digital cameras, but all in all I like digital better because it allows
me to bracket my photos,,,, you know take some one way take some
another, I am finding this a whole lot more fun than paying for
processing and tossing unacceptable pics. Slides were my favorite in
35mm and still have not given up on my Nikon but this is sooooo much
easier and the lag time between taking the pictures and evaluating them
is just great. Hope you folks don't think I am too wierd but this hobby
has had me by the perviabial lens cap sence 1975.
Bruce-n-Gold Beach

 
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OL'Hippie
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      02-22-2006


to answer your last question I take mostly outdoor pictures of the
ocean and the coastal enviroment here on the SW Oregon coast. At least
those are the ones most people like to see.
Bruce-n-Gold Beach

 
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Tesco News
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      02-22-2006
"OL'Hippie" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> Although I am not new to digital cameras I am new to printing LARGE
> prints. So my question is this, with a 6 Megapixil camera shooting at
> 2816 x 2112 (HQ) what can I expect to be the maximum print size, before
> loosing clarity? I know TIFF and RAW are better but unfortunately my
> best pics are at 2816 x 2112 so any help would be appreciated.
> Bruce



Hi.

A 6M Pixel camera will produce a file size of around 18Mb.

I have heard a Photoshop Expert and Lecturer promoting a printing routine,
which advocates that for every inch on the longest side of the print, the
File should be about 1 Mb in size.

10 x 8 inch print size, file size should be10 Mb.
15 x 12 inch print size, file size should be 15 Mb.
20 x 16 inch print size, file size should be 20 Mb

For the Best Quality Prints the file size can be related to the next
standard paper size above.

10 x 8 print - file size 12 Mb
15 x 12 print - file size 20 Mb
20 x 16 print - file size 24Mb

This might not seem very logical because the file size should seem to be
related to the AREA of the print in order to keep the PPI constant. With his
system, as the prints get bigger the PPI gets lower, but the viewing
distance should also be increasing.

He claimed the system is being used by some of the Professional Printing
Labs, who are down sampling in line with his recommendations, simply because
it does work and it also increases their throughput.

Roy G


 
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All Things Mopar
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      02-22-2006
Today OL'Hippie commented courteously on the subject at hand

> to answer your last question I take mostly outdoor pictures
> of the ocean and the coastal enviroment here on the SW
> Oregon coast. At least those are the ones most people like
> to see. Bruce-n-Gold Beach


Thanks for the added info. In all likelihood, you'll be able to
get by with much less PPI, and thus larger "good" prints, for
scenics, so long as there's no fine detail. Arcitecture, some
kinds of still life, and my fav subject, cars, cars, and more
cars, have a lot of detail and demand more PPI.

And, if you're going to make different uses of the same basic
image, it is a good idea to start large and same to some
lossless format. Then resize down and crop as suits your fancy
when getting ready to print. A lossy format such as JPEG /can/
work, if you are careful with the compression and test the
various Chroma subsampling setting you have.

Then, /always/ imediately re-open /any/ JPEG. You really can see
image damage such as atifacts or posterization with the in-
memory bit-map you used to do the final edit.

--
ATM, aka Jerry
 
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Don Stauffer
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      02-22-2006
OL'Hippie wrote:
> Although I am not new to digital cameras I am new to printing LARGE
> prints. So my question is this, with a 6 Megapixil camera shooting at
> 2816 x 2112 (HQ) what can I expect to be the maximum print size, before
> loosing clarity? I know TIFF and RAW are better but unfortunately my
> best pics are at 2816 x 2112 so any help would be appreciated.
> Bruce
>


200 ppi is about the lowest for good results. So, divide 2816 x 2112 by
200, and you get 14 x 10.
 
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