Maximum Image size

[KirstyBurgoine]

Hi,
I need to buy a digital SLR camera that can produce images that can be professionally printed upto 2 metres tall.

I know that different printers have different ways of enlarging and printing etc. and thought that I would probably be ok using the 300D. But, after doing some tests with a friends I could only produce 90cm images at 300dpi without any degradation in quality but when I sent these images to our printers to be enlarged the 2metre version is very blurry.

I also know that the more megapixels you have the bigger the image. the EOS 300D was 6mp and now I'm looking at the EOS 20D which is 8mp.

Exactly how big are the images produced by the 20D? I need to know the actual cm dimensions and the dpi of the images when the camera is on the highest quality setting (including RAW if this makes a difference).

If the 20D is not able to capture images large enough does anyone have any other recommendations?

Thanks

Kirsty

[Jim_T]

Wow.. 2 meters is pretty big.. That's almost 80 inches (over 6 feet)..

Digital images have no size. They're only an array of pixels. The DPI you see in the resulting files is meaningless. It's nothing but the number of pixels in the file divided by the proposed print size. All cameras really produce is an array of X by Y pixels. This is the ony true measure of a cameras resolution. (To determine megapixels, just multiply X times Y).

DPI is a printing term. It's the number of pixels you spread over each inch of paper. At 80 inches, the 3072 pixel wide image gets spread out so you only have 38 pixels filling up each inch.. In other words 38 DPI

The 20D gives you 3505 pixels across.. Spread them evenly over 80 inches and you wind up with 44 DPI.. Not much better.

Even the full frame 16mp 1Ds MKII will only give you 4992 / 80 = 62 DPI on a 2 meter wide photo.

There are some options.. You can upsample the image using software such as genuine fractals.. You can't get more detail, but it will help a bit with the blur.

FWIW, if you want a high quality print that's two meters wide at 300 DPI , you need 24,000 pixels across.. If the print has a 3:2 aspect ratio, that makes a 24,000 x 16000 = 384 Megapixel camera.

[Scottes]

20D printed at 2 meters tall, assuming portrait mode, is less than 50 DPI. So this will look OK when viewed at about 1/2 the distance a billboard is viewed from. I'd guess that viewing from anything less than 5 meters wouldn't look so great.

1Ds MKII is 16.7 megapixels, or about 70 DPI. Not much better.

2 meters at 300 DPI requires over 300 megapixels. However, it would probably look just fine at 150 DPI, so about 75 megapixels - still way out of range of today's digital equipment.

Time to look at medium format and get it scanned.

[Scottes]

My calculations are a little different than Jim's - I still have to do the "meters to feet" conversion (incorrectly it seems). But you get the idea... :-)

[billsh]

As Scottes indicated, the distance you want to view this from is very critical. Will this be a billboard or something viewed from a distance. A sports shooter friend of mine made an image about this size with his 20D. It was posted up high on the wall in the gym of the local high school. Up close, not so good, but at the right distance, it looked fine.

[Roach711]

None of the current crop of (affordable) digital cameras will output that large at their native resolution. however, we've seen many 6 megapixel images that have been "uprezzed" in Photoshop to much larger sizes while still retaining good quality. It just depends how close your viewers will be. If the viewers are at a distance you can print at a low resolution and the pic will look just fine.

Da Roach

[KirstyBurgoine]

Hi,

Thanks for all the info. Is there a better way of achieving this if the digital camera is a no go?

[PhotosGuy]

What kind of image? A landscape can be stiched from several images to get higher resolution. Someone made one that was 1 GB!
And as was pointed out, viewing distance is very important. I've done 4X6 foot images that looked great at 15'. If you're going to print them locally, ask the printer to show you some examples & be guided by them. Or, just print a 8X10" section from the image & see how it looks at the viewing distance you plan to use. Also keep in mind that you will be far more critical than other viewers.

[Bodog]

You might take a look at these photoshop actions. I've never tried anything this big, but he claims 60 X 80 inches.
http://www.nyphotographics.com/ftppage.htm

[Jim_T]

If you want a high quality (looks good at less than an arms length) image that's 2 meters high, you'll have to use large format film or use a large format digital back.

A large format 8" x 10" (25cm x 17cm) film negative scanned at 2400 DPI would do the trick :)