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Photography Question 
George E. Cole
 

How Many Megapixels for the Best Prints?


I am new to digital photography. I understand that a 3 megapixel camera is more than enough to get a good 4x6 photo. I know that more megapixels are needed to get a larger photo with the same quality. However, if the same 4x6 photo is taken with a 6 megapixel camera, for instance, do I still get a better 4x6 photo with 6 instead of 3 megapixels?


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3/5/2006 6:56:46 PM

 
Michael H. Cothran   George,
Theoretically yes, but not necessarily so. A 3 mp image will yield a 4x6 at approximately 360 ppi. A 6 mp image will yield a 4x6 at approx 500 ppi. One's eyes cannot really discern any more detail past about 300 ppi, so saving a file at 500 ppi is overkill. If you downsized the 6 mp file to equal 360 ppi, then your file would be the same size as your 3 mp file is to begin with, thus no difference.
The advantage of the larger 6 mp image is being able to print larger sizes while maintaining more quality and detail. However, if 4x6 is your goal (or even 5x7), then 3 mp is plenty, and anything larger would really be wasted.
Note: You also need to take into consideration whether your 3mp camera is equal to your 6mp camera in terms of lens quality, pixel quality, etc. The optics used on a 6mp DSLR just might give you better color, resolution, and contrast to begin with than that on a 3mp P&S camera. Many factors to be considered here, but, assuming all else is equal, then my opening statement would be credible.


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3/5/2006 8:01:52 PM

 
John G. Clifford Jr
BetterPhoto Member Since: 8/18/2005
  Megapixels are, at best, an indirect indication of the possible quality one can get from a particular image. The rapid rise in popularity of digital cameras has led to the megapixel "arms race" because consumers have wanted one simple number to quantify camera performance.
However, you can't always judge a camera by its megapixel rating. For instance, most 6 mp point-and-shoot 'digicams' give better image quality than their 8 mp siblings in the same product line. Why? Because more megapixels in the same sized sensor means that photosensors (what many people call 'pixels') are physically smaller and thus suffer from reduced sensitivity (and therefore increased noise).
Another example: the Foveon sensor-equipped Sigma SD9/SD10 dSLRs, which are nominally 3.4 MP (according to the way the industry calculates MP, as # of photosites instead of # of photosensors), actually provide image quality as good or better than conventional Bayer sensor-equipped 6- and 8 MP dSLRs.
In short, if you're looking to pick up a good 'point-and-shoot' digital camera ('digicam'), then you'll most likely find the best performance in the various manufacturers' 5- to 6 MP cameras. You will get outstanding ISO 100 4x6 and 5x7 prints from such cameras, and they will be decent at 8x10. More megapixels in this category will NOT give you better enlargements.
If you're looking for under $1k dSLRs, then the various manufacturers' 6 to 8 MP dSLRs (and the Sigma SD10) are certainly worth a look. Due to the increased sensitivity from their larger sensors, these dSLRs will give you outstanding ISO 100 prints at up to 8x10 and decent up to 11x14 or larger, depending on the camera.


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3/5/2006 8:39:28 PM

 
Donna R. Moratelli
BetterPhoto Member Since: 11/23/2000
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  Thank you; This is an excellent discussion. I'm going to further investigate this.


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3/6/2006 5:31:50 AM

 
Bob Chance
BetterPhoto Member Since: 2/19/2006
  I fully agree with both answers that I read in relation to your question about megapixels. To tell you the truth, I only just starte in digital photography a little over a year ago and my first opt (factoring finances at the time) was Kodaks DX6490 which is only a 4 megapeixel camera. The main selling point for this camera wasn't its' size or the megapixels and certainly not it's features, but the lens. The lens is a 10X Schneider.
Having been an avid film photographer over twenty years ago, I am very much familiar with the name Schneider and the high qaulity optics they have produced for a variety of uses, including photographic, for over a hundred years.
The camera itself lacks a lot of features you would normally find in the more sophisticated P&S cameras, but at the same time, what you would gain in features, you loose both in lens quality and megapixels.
The most important thing to consider when buying any camera is the lens. After all, it's the lens that projects the image on the median. No matter how many megapixels you have, or how feature whiched your camera is, if you have a poor quality lens you are going to get poor quality pictures.
Now I'm not out to sell you a Kodak camera, and 'No' I don't word for them either. I'm simply sharing with you what I have discovered and experienced with the little camera I bought two years ago. I've even shot a wedding with this camera and have done portraits and the pictures came out great. Everyone was extrememly happy. Not to mention numerous nature shots and macro shots. One has even been published in a book.
I understand that Kodak now has another similar camera with the same lens but 5 megapixels. Here again, I don't know for certain what type of pictures you intend to shoot, maybe even just family snapshots, but even so, look for whatever camera has the best quality lens and you won't be dissatisfied with the quality of your prints.
BTY - I've made 11x14 prints from that Kodak, and even though they weren't tack sharp, they were still looking pretty good.


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3/7/2006 2:26:52 PM

 
John G. Clifford Jr
BetterPhoto Member Since: 8/18/2005
  Lenses are certainly important, but the physical size of the sensor is also important, as is the sensor technology itself.

No point-and-shoot 'digicam' with the typical small sensor will produce images comparable with those from cameras equipped with larger sensors at the same MP ratings. Small lenses suffer from diffraction at their smaller apertures, much more so than the lenses used on dSLRs. Because of this, images from 3 MP dSLRs (that were leading-edge a few years ago) will be sharper and show more detail and dynamic range than a 4 MP digicam image, and they will look better at 11x14 too.

Yes, Schneider makes good lenses, but it will be rare to get a digital camera today that doesn't have a good lens. In fact, most lenses today outperform the digital camera they're mounted on.

Again, if you want the best image quality, period, get a dSLR. If you want a digicam for handy picture-taking, then get one of the good 5- to 6 MP models. (My favorite is the Fuji Finepix F10/F11.)


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3/9/2006 7:25:13 PM

 
Craig m. Zacarelli
BetterPhoto Member Since: 2/3/2005
  way back when I had bought my first digi cam, it was a 1.3MP olympus... the manual told me it was the equivilent of a 35MM film cam, I was happy. Then a few years later out came the 4 MP camera, I was watching this one on the home shopping channel and the guy said, wow, 4MP's, this is just about as good as a 35MM film camera... this I thought was funny. My digicam took great shots, so naturally, knowing nothing of film cams and digi cams, I could not believe anything could look better.. then fast forward to buying the 8 MP pro1... I started reading about what mp's really were and was a bit surprised to say the least.
Moral of the story, Do not believe a word the guy on TV or at the store or even on the shopping website tells you.. Do your homework and ask, ask and ask again!
Craig-


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3/9/2006 7:31:20 PM

 
Aaron  Reyes
BetterPhoto Member Since: 2/8/2005
  don't forget if you are going to crop the photo, you are going to need those extra pixels.


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3/18/2006 10:37:56 AM

 
Richard Lynch
BetterPhoto Member Since: 6/12/2005
  "if the same 4x6 photo is taken with a 6 megapixel camera, for instance, do I still get a better 4x6 photo with 6 instead of 3 megapixels?"

That may be a little more complicated to answer than just yes or no. It depends partly on what you are doing to print...but also there is a likelihood that the 6MP camera is actually better than the 3MP camera, just because it is probably newer and has some technological advancement.

Differences in cameras aside, 6.3MP for a bayer-type sensor has seemed to me to be the relative equivalent of 35mm film. Where a 3MP camera may render an image that is almost identical to the 6MP on a given inkjet printer at 4x6, you will be able to get larger prints from the 6MP successfully, and it may be possible to get better prints on printers with higher resolution. if you were going to make negatives from your digital captures, the 3MP images may not have enough pixels to render the best 35mm (neg, or slide), where the 6MP likely will.

Having more pixels won't make your images look better simply by having more. the results depend on the camera and the output.

Everyone has their favorite cameras and output...learning to use them as a process will help get the best results consistently.

PS -- my new course on the Photoshop/Elements Workflow can help you hone your process for printing the best images by showing how to use color management, color and image correction, and output as a total process to get the best results every time.


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3/19/2006 7:04:08 AM

 
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