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-   -   how many megapixels will i need??? (

APowers Dec 22, 2004 1:47 AM

what would be the megepixels i would need to do mainly 5x7 and sometimes 8.5x11 photo prints that will look good?

EOS RT Dec 22, 2004 2:37 AM

3.2 MP would in most cases be acceptable. 4 MP is better. You don't need more than 4 MP.

APowers Dec 22, 2004 3:37 AM

Thanks, that narrows down which cameras im looking at and lowers the price a little.

Grinder Dec 22, 2004 7:20 AM

The more the merryier LOL

This was taken with a 1.3 megapix Olympus and blwon up to 8x10 to see how bad it would get. Only small pixelation is seen.

It really depends on the shot. The larger the shot the less sharp - BUT - the larger the shot the more color is important and not sharpness. Below is a post on another forum that speaks of large shots.

Digital is certainly not as good as 35mm. You would need a 25 megepixal camera to be even with 35mm slide film.

Here is a simple formula to figure it out

Long print dimension in inches = 4 x (square root of megapixels)

The D70 is about 6 mege Pix = 2.45

so 2.45 X 4 = 9.8 thus the biggest print you can make without losing sharpness compared to film at normal viewing distances is ABOUT 8x10.

WITH THAT SAID - we're only talking about sharpness! Color is more important to most people.

20 x 30" if you want, since normal people view big images from further away. This is all art and in the eye of the beholder.

JimC Dec 22, 2004 7:35 AM

Don't look at megapixels alone. Many other factors determine how good a print will look (image processing algorithms that effect contrast, sharpness, saturation, etc.; noise levels which can destroy detail -- as you sometimes get with higher resolution modelswith smaller sensors; lens quality, and more).

Here is an article comparing a 3 Megapixel Canon EOS-D30 (a very good 3 Megapixel DSLR model) with 35mm Film:

scifiiman Dec 22, 2004 3:18 PM

wow, trying gto find the right camera without paying for what i dont need is going to be harder than i thought.

Wildman Dec 22, 2004 3:49 PM

Breaking all the rules, I have several very nice 13 X 19 prints shot with an old Canon Pro 90IS (2.6 megapixels). This camera has a superb 37-370mm equivalent lens and the pictures were printed on an Epson 1270 on matte paper.

Bottom line is lens quality, lighting and printer are all factors at least as important as the number of megapixels. Having said this, I really appreciate the 8.2 megapixels available with my EOS 20D.

DennisA Jan 11, 2005 12:08 AM

Grinder, did you read the D30 vs film article? They are talking about large prints which seem to break your rule.

*David* Jan 11, 2005 1:16 PM

Hello, just when I thought I understood resolution re. scanning/photoshop/printing I am now confused again :?. I am interested in the EOS 20D; Steve mentioned 24"X16" prints in his review, but, after doing the maths of 4 X square root of 8.2 megapixels I only get 11".

I am very new to digital cameras by the way, and if you are wandering why I might need big prints, well I have to justify my Epson 7600 somehow :G.


slipe Jan 11, 2005 3:05 PM

Resolution requirements for prints vary considerably with subject, viewing distance and matte versus gloss

The best 16 X 24 crop you can get from an 8Mp DSLR image is 146 PPI. That makes a good print. Download one of Steve's 20D images and crop it to 8 X 10 keeping all the pixels. It will end up around 292 PPI. Resample it to 300 PPI and print it. Then go back to the original crop and resample it to 146 PPI and print it (it wouldn't be a fair comparison to resample the resample). You can see the difference on close inspection, but not at normal viewing distance with most subjects. I don't doubt Steve's contention that you can get a good 16 X 24 from a 20D shot. Maybe not the very best the printer or specialty house could do with more pixels, but very good.

I've run several resolution tests and don't see any improvement at all over about 230 PPI. And 150 PPI makes very nice prints – I have several 5Mp shots printed at 13 X 19 on my wall and they are just a tad under 150 PPI. As printer resolution has increased the dot size has decreased. Smaller dots require more dots to represent a pixel. DPI has increased dramatically with smaller dot sizes, but the PPI required to get best quality has remained about the same.

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