Dave:
1) Dynamic Range:
If you bracket several exposures on the DSLR and use the HDR function
of Photoshop, you will get a wider dynamic range than most
film/scanner combinations.
The dynamic range you will be able to get from a user type scanner (
not a high end drum scanner ) is likely to be less that 4.0. The HDR
files will encode a dynamic range much larger than that. When you
finally reduce to a printable file, the dynamic range will be
considerably less regardless of the source.
2) Image Resolution:
Image resolution on 4x5 camera lenses is significantly less than for
35mm lenses. Typical resolution ( I believe - and others who may
have more specific info please chime in. ) is on the order of 40 lpm
of about 1000 dpi equivalent.. The film will have a greater
resolution than that so enlarging up to 20x24 won't leave you with
about 200 lpm So the 4x5 negative can yield a digital image of
4x1000x5x1000 pixels or about 20 megapixels.
That said, if you are concerned with final image size and landscapes
are your thing, placing the Canon 12MP camera and taking 4
overlapping photos and merging them into a single image of the scene
will get you and image exceeding 30 megapixels. Obviously, having
the camera vertical and taking a 2 x 3 array will yield better than
60 megapixel images. You will have to be careful to make sure that
the rotation center at time of exposure is exactly at the optical
center of the lens else some distortion between frames will
occur. If you are using a 'normal'' focal length lens on the 4x5,
then a good choice on the Canon would be in the 100mm to 150mm range.
3) Output resolution:
The 4x5 at 200 dpi gives you about a .8 megapixel image. The Canon
delivers 12 megapixels, so you are already behind in resolution.
To match the native resolution of the Canon, you'd need to scan at an
optical resolution of 775 dpi, almost 4 times what you are planning.
Hope this gives a reasonable comparison between the two approaches.
Cheers,
James
At 11:51 AM 12/6/2008 -0500, you wrote:
Hello all,
Let me re introduce myself since I've been a way from Photoforum for
awhile. My name is Dave Moore, I live in Syracuse, NY, teach photography at
Le Moyne College, and am also a commercial photographer and even make art
sometimes when my schedule permits.
I am planning to start taking some black and white landscapes, and I am
deciding between two cameras: a 12MP Canon DSLR, or my 4x5 Graflex. I'm
planning on making quite large prints, 20x24", and image quality is my main
concern. I have 3 questions here:
1. dynamic range: I'm doubtful that the dynamic range of my DSLR files, even
when shooting in Raw, can compare to black and white film. Any thoughts
here?
2. image resolution: I'm also doubtful that the tiny little image sensor on
a DSLR, even if it was a full frame DSLR which mine isn't, can compare in
resolution to the 20 sq inches of image surface I get with 4x5, when
enlarged to 20x24", or larger.
3. If shooting with 4x5, I plan to scan the negatives and print digitally.
If I choose an output resolution of, say, 200PPI, does that neutralize any
resolution advantage that 4x5 film would have over a high resolution digital
file?
I'm leaning heavily towards shooting 4x5 but before I do, I want to make
sure that the loss of ease of use of a DSLR is really worth it, in terms of
final print quality.
Your thoughts and reactions here are very welcome. Thanks.
Dave
James Schenken
