6MP Nikon D100 - good enough for critical 24" x 36" advertising posters?

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I am one of those old mares who has stuck clear of digital, apart from
a convenience 8MP small-sensor non-SLR P&S which is fine for what I use
it for.

A friend of mine uses a Nikon D100 and a couple of AF-D Nikkor zooms.
He has asked my opinion as to whether that is suitable equipment for an
assignment to photograph some objects for ADVERTISING POSTERS. The
poster sizes will be 24 inches x 42 inches (2 ft x 3.5 ft). The
subject matter will fill almost all of the area of the poster.

The posters will typically be viewed from a distance of a foot, in shop
windows and on display stands.

While I can't tell you what the subject is, pin sharpness of the end
result is critical for the assignment. Sharpness is an attribute of
the very thing being advertised.

The D100 is a 6 megapixel camera, making 3008 x 2000 pixel images in
its highest resolution mode. It is certainly better than my 8MP P&S
due to the larger sensor size / better noise, superior lens(es) e.t.c.

But I just can't see how the D100 can cut it to reach 24" x 42". Even
assuming that he fills the frame pretty well with the subject so there
is only a 20% loss through cropping (given the nature and proportions
of the subject, that would be excellent), that would mean he would need
to fill 42" with 80% x 3008 = 2406 pixels. That means the "ppi
resolution" would be no more than 2406/42 ppi = 57 ppi, or just over 2
pixels per mm.

Sharpening or interpolating (creating pseudo-detail) software won't
help much, given the subject.

I think that 57 ppi is far too little, given the likely viewing
distances. The general wisdom is that 300 ppi is best for a hand-held
8" x 10" and 150 ppi may be acceptable for critical work with a viewing
distance of over a foot. But 57 ppi is nowhere close to 150 ppi, and I
think the image will look quite pixellated or dotty and, when
interpolated for printing and the end result viewed as a poster,
unsharp.

Given that the advertising posters are aimed at an audience who will
come up to them and look at them closely (some from closer than a
foot), can 57 ppi be enough?

Oh I know ppi and dpi are not the same.

Please tell me your views. Will the D100 cut it for the assignment? I
think a modern 11+ MP SLR just might, and certainly if I could stretch
to a digital back for my Hassy it could. My instincts (more reliable
than my maths, which isn't too good) would be to shoot it on Kodachrome
25 (I have a brick holed away in the fridge) or Velvia 50 (grain being
less important than sharpness for this subject - a little grain may
even be flattering) or similar, and have it drum scanned for good
measure. I'd use a 6x6 on a 'pod. Just maybe a 35mm with a good prime
lens too.

If I am right, how do I diplomatically tell him this? I value his
friendship and he does not take criticism well. The assignment means a
lot to him, and I don't mind loaning him my analogue gear (a modern
Hassy and/or an almost brand new F6).

Or is my friend right, and my maths wrong as usual, and the D100 will
do the job fine?

 

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Sorry, ignore this post, I put the poster size down wrongly as 24" x
36" while it is 24" x 42". Too much working in 35mm, and I told you
I'm not good with numbers.,.

 

I can see the lack of detail in 200 ppi prints at 12" from them. So that
means that a 200 x 24 x 42 x 200 digital original image would be inadequate
to your purpose. That's 40MP.

I'd say a D100 would miss being woefully inadequate by a factor of 7. Not
even in the same ballpark.

If you are using film and inspecting from 12", then you should probably plan
on a 7x enlargement. So that means that you need a 3.4 x 6 inch slide or
negative.

Of course, if you don't wan't photographic quality, then you can use a 3MP
dcam.

You need 5x7.

David J. Littleboy
Tokyo, Japan

 

Hi,
from what I can read, you better forget that camera. At best, you can use -
because you stated that sharpness is the critical topic - a professional
digital back with 22Mpx on a medium format camera. If you would prefer to
stick to film, then I would suggest you to use at least a medium format
(6x7) camera with a slow film (to reduce grain visibility) or better
4x5inch or 5x7 -
rgds George Nyman
http://www.gnyman.com

 

I would assume commercial press printing, though if it is a very short run
then wide inkjet might do the trick. If it was wide inkjet, then the dot
gain is higher, meaning you could get away with a little less. Commercial
press prints are brutal at this size for any aberrations or image
problems; anything wrong will be obvious to nearly everyone. Even if the
client has really low standards or expectations, most customers would
notice any lack of quality, and it would reflect upon the client and that
product.

Having made that statement, I recall a major electronics company using an
image of one product on a large banner. Printing on a banner is screen
printing, which is even more forgiving, but it is still possible to see
any deficiencies. So the supplied image was a 72 ppi JPEG of the product
at about 1" by 1.5", then enlarged in software to about 24" high from the
1.5" high original. The results looked about as poor as you might expect,
though the company was not that concerned since that was the only way to
meet their deadline. Lesson learned is that nearly anything is better than
nothing, though if you have the time it is better to do a proper job of
it.

If it has square edges and shapes, it might be simpler. If it is lots of
perfectly round blobs, the edges might look fuzzy. If it is lots of
diagonals, then you are in trouble.

Much worse than that. Actual optical resolution tests of a D100 indicate
it is only good for around 32 to 33 lp/mm. The chip size is 15.6 mm by
23.7 mm. So 24" is 609.6 mm and 42" is 1006.8 mm, which means that the
target printed size is 45 times the size of the chip. In other words, the
final printed resolution would be less than an actual 1 lp/mm.

Sharpening can create more edge contrast, giving an appearance of apparent
sharpness. Interpolation can help smooth transitions of colour, but will
never add information that was not there to start.

Well, it will either look like coloured oatmeal, one of those funny 3D
pictures you need to stare at to figure out, or it will look like lots of
little square cubes turned into an image. You could try turning the
original into an EPS or DCS file to enlarge it, which might help smooth
the edges and avoid some aliasing.

If you want it to look like illustration, or if they mostly have really
bad eyesight, then it might work.

Pixels per inch and dots per inch. The difference is actually the size of
each individual dot, which varies with printing methods. Your source file
originates from a 7.8 µm cell size on the D100. Commercial printing dot
sizes can be 10 µm on up, or variable dot sizes from some newer equipment.
These are also overlapping for each colour plate, and it should be noted
that they are more round than square due to dot gain.

Fuji Astia 100F (low saturation) to Kodak E100VS (high saturation) or
somewhere between those. Maybe 6x7 due to the more rectangular crop of the
final print. Might be cheaper to rent some gear an sustain less
enlargement multiple, than risk a quick fix with small format gear.

Send him over to DPReview, and have him look at the resolution tests for
the D100. Then sit him down and do the math.

I should mention that with the job for that major electronics company that
I related above, I was the person contracted to upsize the image. I warned
them about a lack of quality, yet they went ahead due to tight deadlines.
The upsizing method was complicated to get a reasonable representation of
their product, and avoid obvious problems. Sure, the final printed banners
looked soft, though they avoided blocks, pixelation and aberration.

In theory, he could do the job with the D100. My feeling is that he could
do a better job with something else. Commercial printing is much less
forgiving than wide inkjet, though even the worst of wide inkjet systems
can reveal image problems. He can do the job quick and cheap, or he can
take a little more time to do it right at the start. It is very difficult
to just hope software can solve deficiencies in the images. I wish both of
you luck.

Ciao!

Gordon Moat
A G Studio
<http://www.allgstudio.com/technology.html>