Re: digital question #3

Etienne has already answered some of this (and with less words, who me
long winded??). There are really five things to investigate before
buying a dig, and they are roughly equal in importance: MegaPixels,
Noise, Dynamic Range, Lens, and Form/Features.

MEGA PIXELS:

Often the only thing folks worry about. Cause or effect?: often the
main thing advertised!

For web use (as Etienne already said) you are fine with either of your
choices. Trying to work in any form of "inches" for current web work is
just frustration. Some of use have native 72dpi monitors and we've
deliberately set them to something else, others don't even start at
72dpi before they change the setting! The more common monitor settings
are 640x480, 800x600, 1024x768, and 1280x1024, some of the newer giant
LCDs reach 1920x1200. I wouldn't suggest web designs for larger than
1280x1024 (actually I would advise smaller). So, for web work anything
larger than 1200 wide can't be completely seen (you have to save a few
pixels for the web page frame). Your "3 mpx" is typically a 2100x1400
pixel camera, so that is bigger than my biggest suggestion (1200). I
more typically get asked for 500 pixel images from web designers.

Print is a whole different discussion, and it depends on personal
choice and type of output.

For inkjet you will hear as low as 200dpi being optimal (as Etienne
said), I like a minimum of 240dpi and prefer 360dpi for glossy papers.
There are a few photographers that swear they see an improvement at
400dpi. Much of this variation is the printer/ink/paper combo used.
Some of it may be the age of the photographers eyes! Your 3 mpx camera
would typically give a 10.5X7 inch at 200dpi, an 8.75X5.8 inch at
240dpi (my minimum), a 5.8X3.9 inch at 360dpi (my prefered), or a
5.25X3.5 at 400dpi. A typical 5 mpx is 2700X1800 pixels and would give
a 13.5X9 inch at 200dpi, an 11.25X7.25 inch at 240dpi (my minimum), a
7.5X5 inch at 360dpi (my prefered), or a 6.75X4.5 at 400dpi.

For inkjet negs intended for alt work I find 240dpi perfect (alt papers
have more texture, and thus less resolution, than glossy inkjet paper),
Burkholder suggest 360dpi.

If you are getting it commercially CMYK press printed they will
typically want 300dpi for a 150 line screen (good magazine quality) or
350dpi for a 175 line screen (excellent magazine quality / coffee table
book quality).

I keep saying "typically" above because different cameras have
different aspect ratios, but the above numbers will be close.

NOISE:

Just as important as megapixels in today's 3 meg and larger systems!
Much harder to measure in a meaningful way (and thus much less
advertised). The small consumer sensors are noisier than the larger
DSLR sensors. Laws of physics, a larger photo sensor is quieter. But,
within a given size the manufacturer can determine what the noise looks
like. It can be sharp out of color dots or a generally correct color
smudging. Both will "measure" about the same :-(

Best answer is the much suggested DPreview ( http://www.dpreview.com/ )
where you can see enlarged samples of each camera's noise and decide
what will bother YOU the least. Much as with film grain, the lower ISO
you use the less noise.

DYNAMIC RANGE:

One of digital's big problems. A typical 8 bit JPG is like shooting
slide film (fine in soft light if you bracket). Some cameras have
LIMITED abilities to adjust the contrast, much better is the ability to
shoot 12bit RAW files. These have a range more like negative film, but
do require more computer time. Photoshop CS is a great answer for RAW,
as it will open "most" RAW camera file types. Otherwise you have to use
the manufacturer's program to convert the RAW to a tiff, and then open
that in Photoshop.

LENS:

Isn't it amazing that we've forgotten about these? Too much new
technology blinding us to the obvious? A lens is just as important on a
dig as it is on a film camera. Watch the F/stop range, many of the
compacts get dangerously slow. Remember that almost all of the digital
zooms are variable aperture, so see what the "bad news" is at the tele
end. Much can be discovered by looking at DPreviews resolution tests,
although that leaves flare out of the equation.

FORM / FEATURES:

Do you want/need small? Do you want simple quick operation or lots of
options? What type of memory do you want to use (already own)? Is the
manufacturer's (typically poor consumer grade) software important to
you, or do you already own Photoshop and a catalog program and a card
reader?

I know I may have caused more question than I answered, but hopefully
I've helped show you where to find YOUR answers :-)

On Saturday, July 31, 2004, at 06:39 PM, steves wrote:

> One more time: What are the merits of 5mpx versus 3 mpx.
>
> All we want is to photograph art work for web submissions and to make
> prints
> for a folder.
>
> The cost is significant, or insignificent if the difference is . . .
> significant or insignificant. :)
>
> Thanks group,
> Steve Shapiro
>
>
--------------
Tom Ferguson
http://www.ferguson-photo-design.com
Received on Sun Aug 1 10:13:27 2004