Hi

The math is kinda simple.  The eye sees about 8 lines per millmeter at 10
inches.  So that is what you need to make a exact 8 ft by 8 ft original.  

Now all you have to figure is the reduction.  8 ft x 8 ft to a 1 ft by 1 ft
image is a 1:8 reduction.  The resolution will need to be 8 times as great or
64 l/mm  on the 1ft by 1 ft image This can be done with modern equipment and
film.  

Larry

I would consider doing something with digital printing. Should work fine for
a charcoal drawing.

Let's calculate how well it could be done with 35-mm equipment, just as a
point of comparison.

I presume this is color, so you'll be using something like Ektachrome 100 or
Fuji Velvia film with a resolution of about 100 lines per mm.

Your camera lens, assuming a very good one, will probably resolve at least
half this; say 50 lines per mm.

That's across 1 inch of film.  Your original is 8 x 12 = 96 inches wide.

So on the original, you will be resolving 0.5 lines per mm.  That will *not*
capture the details of the pencil strokes, or whatever, although it will
look fine when viewed from a distance.

I'd suggest 4x5-inch sheet film as a minimum; 35-mm is not up to the task,
but something 4 times bigger (4x5) probably would be acceptable.

Making the enlargement will be much harder.

Have you considered using digital technology?  Again, even the best digital
SLRs right now aren't going to do any better than 35-mm film.  But you could
cheat by running a sharpening filter to bring out some detail that is partly
lost.  The results might be quite pleasing, and you could make the
enlargement on a digital printer.

   I think 4x5 would do it, 35mm definitely would not. Use
something like 100T-Max. The big problem is going to be
printing it, the same problem as in photo-murals.  Vibration
is the enemy here. You will have a long throw and probably a
long exposure time. Depending on what's available in your
area having the negative scanned and printed electronically
might result in better quality. Electronic printing will
also give you the ability to modify the image if desired.
Increasing edge sharpness is not possible for large
negatives since "acutance" effects are of fixed scale.
   Using as long a lens as possible on the camera will help
with uniformity of illumination of the negative. You may
have to use polarizers on the lights and lens to eliminate
surface reflections.  It is certainly a practical project, I
rather think the best technique is to use a photographic
negative and electronic printing.

Folks thanks for the info.

I assumed 4x5 without really thinking about it and it seems the way to
go.  As cost is not a factor I am considering tmax 100 4x5 and then
having it output onto a digital printer (lightjet/vutek?)  ..Not sure
what the client wants as far as material...

Q: So why not just frame the original?

A: How many houses do you know can fit 8'x8' framed drawings into
their doors? :)

Cheers,
-sd
http://www.zoom.sh

I never considered doing this job with digitals but...

I do have two digitals.  A D1X and a D100.  They are both right around
6MP.  I don't know too much about them technically but based on some
preliminary tests on my inkjet (epson 2200) and a loupe seems to imply
that a 6MP camera can't even get close to a blowup of the size I am
requiring. (minimum 3-5' x and y).  Maybe i'm wrong- I don't know the
megapixel-to-print size ratio either..

Cheers,
-sd
http://www.zoom.sh

Dude:

Trust your 2-1/4 camera to do good job. Use the slowest
film you can obtain, with a really sharp developer like Rodinal
diluted 1:100.  When I had to do such work I used Agfa !FF,
Panotomic X, or  ADOX KB-14. Making the enlargement is
just a matter of turning your enlarger around on its baseboard,
so that it overhangs your desk, and projects the image to the
floor. Raising the baseboard with boxes will get you still larger
images.

If that isn't enough, obtain a first surface mirror and place it
under the enlarger lens at a 45 degree angle. This way you
can project the image across the darkroom as far as you need.
Use two-sided tape to hold the paper to the wall. Be mindful to
take some of the tackiness out of the tape, or the paper will
tear when you try to remove it the first time.

With this method I've made murals from subminiature negatives as
small as 10 x 14mm in area. So your 2-1/4 negative should be just fine.

Best regards,

Al Doyle

alldoyleZ@att.net  (please remove the Z)

    Shoot with the largest camera you have available. Preferably
8X10 which is easily scanable on a Howtek 8000.

Regards,

  John S. Douglas, Photographer -  http://www.darkroompro.com
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