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Old Aug 21, 2006, 4:11 PM   #1
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I am trying to understand the megapixel thing and this is my question. If I want to put a picture on the computer and I take a picture with my 7.0 megapixel camera on superfine(7.0) the pictures are huge. If I use it on normal the pictures are smaller but this is less megapixels correct?

So if I want a picture that is say 5 x 7 size to show on the computer would I want to take it on superfine(huge) and then resize it down with photoshop? Would this degrade the quality of the picture? Or would I want to take it on a pixel setting closer to the 5x7 I want for final product? Does that mean it will be less quality though if I use less than the 7 megapixels?

I was told that if I only want 5x7 pictures I don't even need the 7.0 because that is just for poster size pictures. If this is true, why would anyone want a bigger megapixel camera if they just want regular size photos?

What I am trying to get is the clearest 5x7 pictures so do more megapixels matter or am I missing something?
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Old Aug 21, 2006, 4:48 PM   #2
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Fine/superfine/normal etc all use the same number of pixels (the same resolution) , just the compression of the jpeg file is altered.

Normal would use more compression (smaller filefor storage purposes, crappier looking pic)

Fine and superfine would use less and less compression , resulting in a better picture, with less visible jpeg artifacts.

Remember jpegs which are compressed pictures, work by throwing away picture information, you can never get that information back, the higher the compression the blockier the pictures seem and the more "blurred" details become.

See, http://graphicssoft.about.com/cs/dig...ompression.htm

So unless very very pressed for memory space in the camera, use the most pixels you can (highest resolution) and at the lowest compression .

The higherresolution gives you more fine detail, and the more you can crop the picture later, while the lowest compression limits the damage (artifacts) you see in the picture.

After all, memory and storage (cds and dvds) are very cheap.

If you are only printing small then , yes you could reduce the resolution of the picture to be able to fit more onto the memory card ie instead of 7mp your camera might over 5mp or 3mp or even vga (640x480) ,but what happens in the futureif you want a poster made ?

You can neverget back the pixels you never shot in the firstplace.

As to why people want more and more megapixels, umm.

Well obviously we may want to print bigger one day , but the real reason is this.

Newbie walks into a camera shop, salesman sees a walking talking paycheck ..

Newbie - "is that camera any good?" pointing at a 5mp camera perfect for his 4x6s or 8x10s.

Salesman "why yes sir, but this camera the Superdooper10k , is 10mps, thats twice as good as the other"..

Newbie "wow, 10 mps... let me have one of those ..."


Now really a 5 mp (or indeed even 3mps)printed on a 4x6 will not be any way different to 10mp printed on a 4x6, the human eye will not be able to tell the difference.

However the newbie does not know that, he just knows that Fred next door only has a 5mp camera so his camera is thus twice as good..

Its why we buy cars capable of 3 times our national speed limit, not so we can necessarily get to that speed (a ban and jail time ...) but so we can boast.










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Old Aug 21, 2006, 5:38 PM   #3
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Sintares wrote:
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Fine/superfine/normal etc all use the same number of pixels, just the compression of the jpeg file is altered.
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~~~That makes sense! I get it now.

Normal would use more compression (smaller filefor storage purposes, crappier looking pic)

Fine and superfine would use less and less compress, resulting in a better picture, less jpeg artifacting etc.


Generally always use the most pixels you can, the more you have the more detail, the more you can crop etc etc.
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~~~~But what about resizing in photoshop, does that degrade the picture when you resize from a large format?




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Old Aug 21, 2006, 6:03 PM   #4
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But what about resizing in photoshop, does that degrade the picture when you resize from a large format?

Do you mean print a large picture ( a lot of megapixels ) to a small size , say 4x6 ?

Well, you aren't changingthe actual number of physical pixels in that case, the pixel number remains the same, you are simply fitting a lot of pixels into a small size of paper (increasing the pixels per inch)

The human eye can't tell the difference over around 300-350 pixels per inch, so printing a 4x6 at 300 ppi and one at twice or four times that will yield no easilyvisible difference.

So what I am really saying is this, a 4x6 will look great from a 3 megapixel camera, it will also look great from a 5/7/10 or 16mp camera...

Will you be able to tell the difference without a microscope and 20 years experience in the printing or photographic trade ? Probably not .. :lol:



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Old Aug 21, 2006, 10:36 PM   #5
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If you want to resize for display on a web site, in order to keep down the file size, then you will lose some information. For this reson, you should always keep your original at full resolution, and rename the pictures for posting on web pages. I also keep them in a different folder on my hard drive, to further separate them.

In general, you should use all the resolution possible for prints, particularly if you want to print larger sizes, and reduce to appropriate size for web, but usually no larger than 800x600 pixels, to accomodate those with older or smaller video cards and monitors. Larger sizes can be clumsy to view with web browsers, though IE, for example can be set to resize the image to fit the screen.

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Old Aug 22, 2006, 1:06 AM   #6
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VTphotog wrote:
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Thank you so much both of you for all this information that clears up my question!
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If you want to resize for display on a web site, in order to keep down the file size, then you will lose some information. For this reson, you should always keep your original at full resolution, and rename the pictures for posting on web pages. I also keep them in a different folder on my hard drive, to further separate them.

In general, you should use all the resolution possible for prints, particularly if you want to print larger sizes, and reduce to appropriate size for web, but usually no larger than 800x600 pixels, to accomodate those with older or smaller video cards and monitors. Larger sizes can be clumsy to view with web browsers, though IE, for example can be set to resize the image to fit the screen.

brian
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Yes this isexactly what I was wondering. I want to be able to have clear beautiful pictures for a webpage at a smaller .jpg size, but I also want to be able to print them later. So what I will dofrom now onthen is always take my pictures at the highest resolution (superfine 7mps) and then save them in a separate folderfor printing later and then have an additional copy to crop and resizefor my webpage. Next to figure out lighting:?Thanks again!
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Old Aug 22, 2006, 6:11 AM   #7
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http://www.kenrockwell.com/tech/mpmyth.htm
THe Megapixel myth

Summary: megapixels in cameras are numbers used by companies to separate you from your hard-earned cash. Same thing goes as far as those 2880 dpi ek ek printers are concerned... as if your eye could spot the difference. :?

Since you asked about 5" x 7" inch pictures let us do a little computing shall we.
Since most developers print at 300 dpi, a 5" x 7" pic would use
(5 x 300) x (7 x 300)
= 1500 x 2100
=3,150,000 or simply 3 MP

Therefore for a 5x7 pic all you need for an excellent pic would be a 3 MP camera. Beyond that would make no difference on your printouts since that would be not really significant unless you are the type who crops and enlarges areas of photos. But for those who simply crop photos, a 3 MP camera will be good enough.

Don't let the 7 or 8 or 12 MP number fool you because if you print 5 x 7s all you need is a 3 MP resolution.
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