how big can you blow up...

[Dylan Couper]

Just wonder what size these digital photos would print at naturaly, and what size they can be blown up to while still achieving acceptable quality?
640x480
1600x1200
3072x2048

Thanks

[Rob Lohman]

I've printed my 1600x1400 photos from my camera up to about
letter/A4 size without it looking bad (in my eye)... But then again
I'm not really into still stuff, so...

[Paul Tauger]

I print my 6M shots from my Canon 10D at 13 x 19 and get results that are indistinguishable from (and even surpass) the chemical film & paper 16 x 20 prints I used to produce in my color darkroom (until I sold it and bought a good digital photo printer ;) ). Examining the grain pattern with a loupe, I don't think it would be practical to go much larger than 13 x 19. However, there are programs that will extrapolate intermediate pixels that, at least as I've been told, allow producing poster-size or better.

[Paul Tauger]

As a follow up, and in response to the first part of your original question, there is no native size for a give resolution -- everything depends on the dots-per-inch you select for your printer. The usual rule of thumb for producing photo-quality digital prints is to use 200-300 dpi (I usually prefer 240 dpi, though I know of folks who use 225 dpi). At 240 dpi, you'd get the following print sizes:

640 x 480 = 307K = 2.6" x 2"
1600 x 1200 = 1.9M = 6.6" x 5"
3072 x 2048 = 6.3M (Canon 10D resolution) = 12.8" x 8.5" (roughly A4)

[Dylan Couper]

Perfect answer!

Thanks Paul!

[Jeff Donald]

Just to keep matters clear, image files use ppi (pixels per inch) and printers use dpi (dots per inch). Some argue that files that go to the printer should be at a multiple of the printers resolution. For example if a printer prints at 1440 dpi then the files sent to it should be 240 ppi, 360 ppi, 480 ppi, or 720 ppi.

Increasing the ppi through interpolation doesn't create new data and the image files can get huge. I use an Epson 2200 and send files to it at 360 ppi. The printer resolution is set to 1440 dpi unless I'm going to 13x19. If I'm printing 13x19 some images seem to benefit from printing at 2880 dpi. The disadvantage of printing everything at 2880 is increased ink consumption and slower print times.

[Chris Hurd]

For what it's worth, you can get an 8x10 from a two-megapixel image (1600 x 1200). It's definitely pushing the limits, but it's possible, although a bit of softness will be present in the print. I've got a Canon print sample book with a number of two-megapixel 8x10's which look great, as long as you don't put a four-megapixel print next to 'em.

[Imran Zaidi]

I work at an organization where we frequently create several glossy magazines, comparable in quality to what you see on the newsstand. Often there is need for product shots and such for ancillary stories, and I'm usually asked to take those shots. Over time, we've come to realize, that in the magazine world, you don't want to go below the 3MP range if you want a full page photo (letter size).

But what's also important is that it's more about the quality of the camera than MP size. I've used 4MP cameras that just don't look all that good. I've found Canons to be my favorite for this application. I have, however, never used a Nikon digicam. I've found several Sonys to be good too, but they need to be color corrected more than the Canons.

[Chris Hurd]

The difference is in the camera's image processor. While the megapixel rating primarily determines the maximum print output size, the actual quality of the image depends on the processor. Canon's CPU is proprietary technology, built from the ground up as a photography-specific chip. All others are off-the-shelf electronics components that can be found in PlayStations, Gameboys, X-Boxes, etc. Although Nikon does look very, very good.

[Dylan Couper]

Thanks guys!

Out of curiosity, how big can you blow up 35mm film?

[Imran Zaidi]

I'd say sky's the limit with that. I mean, unlike digital shots, when you blow up 35mm, the worst that happens is that it gets fuzzy edges, not nasty pixelated edges. Plus the larger you get, the less important resolution really gets. Like billboards - those things are printed at something like 100dpi, but it's not like you look at them up close.

Plus, they do, after all, project 35mm film at billboard sizes every time you go to your local theater.

Ultimately, the most important thing is that at blown up sizes, film just starts to look soft. But it's very tolerable. Digital shots that are blown up past their recommended size just look nasty.

I've blown up unexceptional 35mm prints up to movie poster size before, with no complaints. Imagine what you can do with well shot slide film...

[John Garcia]

ive seen a post size print of the Digital Rebel's image (basically the exact same image as the 10D) and the image looked AWESOME! hardly any grain at all! so much information...

you could try a program called "Genuine Fractals." It does an awesome job of blowing up images with awesome results...

[Jacques Mersereau]

We have a large format printer here at The Media Union. It's a Hewlitt
Packard and is about 4 years old. It can only print at 75 DPI.
I have printed out some 10D stills 3 feet by 4 feet. Although
their quality is not stupendous compared to what the newer
printers can accomplish, most people are awed by them.

The 10D is amazing and if Canon can get this kind of quality and resolution
in the XL2 I will be the first to open my wallet.

[Jeff Donald]

Out of curiosity, how big can you blow up 35mm film?

Film is limited by grain. In most cases a print larger than 16x20 will not appear acceptably sharp. Digital images lack noise (grain) and are not limited in size by grain. Digital images, however, will show a lack of resolution that limits the maximum size of the digital image.

There are techniques for both film and digital that allow larger size prints to be made with minimal grain or sufficient resolution. A 4x5 interneg can be used with film to help reduce grain. Specialty software can be used to enlarge digital files.

Several digital cameras produce files that equal or exceed 35mm film. Viewing distance is of great importance. Billboards look sharp because you're viewing them from extreme distances (hundreds of yards in most cases).

[Matt Betea]

Jeff,
I had a question that you could probably help me with. In developing a negative (35mm), would developing to scan and to print traditionally be the same? Or would a developer suited for printing on an enlarger not necessarily be good for a negative intended to be scanned and printed? Thank you for your help.

matt