# Camera size vs enlargement size.

Discussion in 'Darkroom Developing and Printing' started by Some Dude, Jun 24, 2004.

1. ### Some DudeGuest

How-dy.

I need to copy (photograph) an 8x8' (yes, foot) charcoal drawing and
then reduce the photo to something that will fit inside a door (e.g.
around 4x6'). I am wondering what sort of camera I am going to need
for this to print without having to enlarge the transparency. Is this
impossible? 4x5? Bigger? gulp, 8x10 format?

I am hoping to retain the exact original quality and then even have a
sharper output when the image is reduced.

Am I dreaming?

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

Some Dude, Jun 24, 2004

2. ### Hemi4268Guest

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

Hemi4268, Jun 24, 2004

3. ### Mark AGuest

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

Mark A, Jun 24, 2004
4. ### Michael A. CovingtonGuest

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.

Michael A. Covington, Jun 24, 2004
5. ### Richard KnoppowGuest

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.

Richard Knoppow, Jun 24, 2004
6. ### Hemi4268Guest

Hi

Actually you could do this in 35mm if you take enough pictures. Just figure
where you would get about an 8:1 ratio reduction and snap away. Scan all the
images and put them together with a good merge software.

Larry

Hemi4268, Jun 25, 2004
7. ### Some DudeGuest

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

Some Dude, Jun 25, 2004
8. ### Some DudeGuest

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

Some Dude, Jun 25, 2004
9. ### DigitalisGuest

You can do it with the digitals if you are careful. Create a mosaic of
shots, then stitch them together using Photoshop or stitching software.
Use care in how you create the mosaic, you need to know where each shot
goes.

As for megapixels you need keep in mind that most printers work in the 200
to 300 dpi range. As a rough guide, take your final image size, say
5 feet square, convert to inches (60 inches square) then multiply each
final dimension by the resolution requirement of your printer. In this
case, for a 300 dpi printer:

total pixels = 300 dpi * 60 inches high * 300 dpi * 60 inches wide
total pixels = 324,000,000 or about 324 megapixels.

It is an exercise for the reader to figure out how to get a mosaic of this
size and whether it is necessary for a satisfactory print. Note that
viewing distance is not taken into account using this calculation, and you
may be happier with a smaller mosaic.

Digitalis, Jun 27, 2004
10. ### Nicholas O. LindanGuest

Work backwards:

sqrt (6,000,000) =~ 2,500 pix/side

5ft = 1524 mm

The smallest pix you can do is .6 pix/mm

I will leave it to someone else to determine the minimum viewing
distance.

Nicholas O. Lindan, Jun 27, 2004
11. ### Nicholas O. LindanGuest

[5ft x 5ft print with 6Mpix camera - what happens]
Eye resolves ~1 arc-minute = 1/60 degree = 3e-4 radians

Using sin(a) ~= a in radians

pixel size / distance = 3e-4 rad

distance = 0.6 / 3e-4 = 2,000 mm = 2 m =~ 7 ft

If you keep the audience kinda far away the
print will look OK.

In the general case a 6Mp picture will look
OK if it subtends 40 degrees or less.

Nicholas O. Lindan, Jun 28, 2004
12. ### Peter ZissonGuest

Q: So why not just frame the original?
Actually, a flat sheet 8' sq. is not that far from the opening of a standard
36" door, which is about 85" corner to corner. If the backing is flexible
it could be curved without kinking.

Peter Zisson, Jun 28, 2004
13. ### Al DoyleGuest

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

Al Doyle, Jun 28, 2004
14. ### JohnGuest

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

John, Jun 29, 2004
15. ### JohnGuest

Not only can I fit them through my doors, also through my
windows. Try making that into a darkroom !

Regards,

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

John, Jun 29, 2004
16. ### JohnGuest

the early 60's.

Regards,

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

John, Jun 29, 2004
17. ### Some DudeGuest

Forgive me for picking on you but, rodinal diulted 1:100 is not
"harp". I am somewaht familiar with this stuff for its exact
*opposite* properties. So maybe you're talking 1:25 but 1:100 you're
on crack, man (not flaming you).

Tmax 100 is the perfect 4x5 film to use for this project, i'm
convinced. Anything slower is probably not worth it and not
necessary.

You have some great *inventitive* ideas there but I'm shooting big -
Sinar P2 with a Rodenstock 65/4.5 is what i'm planning to shoot with
right now.

The transparencies are going out to a lab to be printed on the same
paper the charcoal was done on (charcoal paper? its like a rough
yellowish constructon paper).

I will keep this in mind for future thoughts.

Thanks.

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

Some Dude, Jun 30, 2004
18. ### Some DudeGuest

hear hear John!

Sorry I don't have enough time in the day to get the miniscule
particulate that accumulates on my CCD after changing a lens in a
walk-in autoclav.

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

Some Dude, Jun 30, 2004
19. ### one_of_manyGuest

Charcoal images generally have a very compressed tonal range and are well
suited to very fine, high-contrast film - or very fine film underexposed
and over-developed. 4x5 will do just fine. Even 6cm will work.

one_of_many, Jun 30, 2004
20. ### JohnGuest

Tech Pan, 4X5, HC110 Dil. F, EI 16.

Regards,

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