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Old Sep 15, 2010, 9:28 AM   #1
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Default When do you stop seeing a difference in MP's?

If you are not enlarging, staying in the 4 x 6, or 8 x 10 range , when do you really stop seeing a difference? With the same say canon lens, at 8mp, 10, 12, 15mp's?
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Old Sep 15, 2010, 9:41 AM   #2
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6mp with a good lens on a dSLR, assuming low ISO will still be higher than is needed for very good prints at these sizes. You can't quite get 300dpi at the 8x10 but will be close enough not to worry.

I've shot for posters 30x20" with a 6mp camera with no worries at all, even under scrutiny it's more than acceptable.
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Old Sep 15, 2010, 10:02 AM   #3
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Quote:
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6mp with a good lens on a dSLR, assuming low ISO will still be higher than is needed for very good prints at these sizes. You can't quite get 300dpi at the 8x10 but will be close enough not to worry.

I've shot for posters 30x20" with a 6mp camera with no worries at all, even under scrutiny it's more than acceptable.
I guess my other question is why do the mfg's keep cranking up the MP's,
Like the canon t1i 15.1 vs the t2i at 18mp's? Is it getting to be just bragging rights?
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Old Sep 15, 2010, 10:10 AM   #4
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Whatever your print size, there's a lot of resampling going on. The results of the resampling affect the print quality as much as do the megapixels.

I've got two 8x10 photos hanging on the wall of my dining room, of my wife competing in Dressage. One was shot by a pro onto film. The other was shot by me with a 3MP P&S and cropped to about 2MP. You can't tell which is which without an eye loupe.

More megapixels is better, but the law of diminishing returns applies. The difference between 6MP and 8MP is more significant than the difference between 16MP and 18MP.
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Old Sep 15, 2010, 11:24 AM   #5
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I guess my other question is why do the mfg's keep cranking up the MP's,
They're a victim of their own marketing machines. When digital first started out with 1mp cameras, every increase in MP was important. Once we got to 6mp the importance curve really stopped climbing. But by then, number of MP was the single most recognized metric the general public associated with how good a camera was. For non-knowledgeable photographers (i.e. the huge masses of people buying cameras) I run into when I'm shooting with my DSLR, the first question they invariably ask is - Wow, how many megapixels is that? It's ingrained in the pubic psyche - more is better. So, manufacturers must constantly stuff more MP on cameras - even though most photogs won't benefit much from it so those cameras are perceived as being good enough. To put it into perspective, the vast majority of professional sports photographers on the market are shooting with cameras that have 12mp or less. We're talking the Olympics, World Cup, what you see on ESPN, Sports Illustrated, etc. Pretty demanding stuff. Now, there's no question there is a segment of photographers that benefit from more - but we're not talking about that segment. So, rather than spend R&D $$$ on making greater strides in dynamic range, noise performance, AF performance, metering, or a host of other advancements, manufacturers have backed themselves into a corner. They have to pack more MP in their cameras and spend precious R&D $$$ trying to not degrade IQ or noise performance to keep up with the perception they created that megapixels are the single most important feature in a camera.
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Old Sep 15, 2010, 11:52 AM   #6
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Thanks, makes a lot of sense now. I so agree with when I am taking pictures, the first thing people ask is how many pixels is that camera.

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Old Sep 16, 2010, 2:25 AM   #7
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There are limits on the printer technology beyond which improvements are not readily visible. On the high end printers that's probably now around 480dpi (droplets per inch).

However total system resolution is a function of all the elements in the imaging chain. Increasing resolution can help the overall output up to values which make today's megapixels seem piffling.

http://theonlinephotographer.typepad...be-enough.html

400 Megapixels for an 8x10?
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Old Sep 16, 2010, 6:23 AM   #8
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One thing I didnt see mentioned is increased resolution gives you the ability to crop tighter for those shots where your reach in glass fell short. There is a huge difference between a 100% crop at 6MP and a 100% at 21mp.
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