Question regarding downplaying large MP worth

[ClickAddict]

I've seen many posts in here and other forums stating that after a certain value (lets say 12MP for instance) getting a camera with more MP is only important if you're going to be making larger prints.

One thing which popped into my head and I haven't seen mentioned is that doesn't higher MP equate somewhat to longer zoom (allowing for crop) in a sense even when just printing 4x6 shots?

I'm imaginning the following test:

2 cameras - a 12MP and 18MP side by side on tripods both with equal lens (lets say a 70-300mm). someone holding a coin in their hand moving further away from them. Goal is to take a shot with the coin filling 100% of the composition from top to bottom after it has been printed and the quality of the picture clear enough to read all the text on the coin at that size. Logic would dictate that you could certainly crop in more with the 18MP and still have the same quality as the 12MP so in effect you've added to your capabilities of catching things further away, which for Birds, sports etc.. is critical.

But I've never seen this argument when people are asking suggestions for cameras. I usually see the "oh well, XX MP is enough, the difference is in the glass." Not knowing the math behind figuring out how much more I could crop to get the "same quality picture" of the coin for instance I don't know how much % more "zoom" if you want to call it I would get out of the higher MP camera to know if this is something to be considered or not.

This is all just for curiosity. I'm not purchasing, but being knew I was wondering if there was something wrong in my logic.

 

[Robin Usagani]

Yeah you are right. Cropping is essentially the same thing as large print. I like my print to be somewhere between 200 and 300ppi without using software interpolation. But what you are talking about is cropping the heck out of the photo. If you do that then your resolution is going to be below 200ppi and will not produce quality prints.

 

[ClickAddict]

I'm not trying to get a larger print. i'm trying to compare what people argue that if you are only printing 4x6 then there's no point in getting a extra high MP camera. I'm thinking the extra high MP camera will give me longer range (for equal lens) than the lower MP camera to take the same looking shot since I can crop more and have the same quality.

 

[ClickAddict]

Using your 300ppi for instance, Lets say were both standing X number of feet from a person, using identical lense full frame cameras etc.. The only difference is one has a 12MP and the other 18MP. We want to get a shot of the person and print a 4x6 at 300ppi after we've done cropping (ignoring software interpolation) Couldn't the 18MP "get closer" to the subject since it can crop in tighter to get that 300ppi?

To me this would appear to counter the "higher MP's dont matter etc... for small prints" since you've just added to your lenses possible focal range.

Again I'm new, not trying to argue, just understand the downplaying of the MPs I often see.

 

[nonamexx]

Since the size of the sensor and lens remains relatively the same on most P & S cameras, cramming more megapixels will actually deteriorate the quality of the image.

I am not sure about dSLRs with larger sensors. They might benefit from more megapixels.

I rarely take photos above 5 MP on a P & S camera.

 

[Robin Usagani]

You are right. What you have to realize though 18mp is not a huge jump from 12mp. Just based on the # it looks like a huge jump, but its not. 18MP is actually only 22% wider in pixel count.

Using your 300ppi for instance, Lets say were both standing X number of feet from a person, using identical lense full frame cameras etc.. The only difference is one has a 12MP and the other 18MP. We want to get a shot of the person and print a 4x6 at 300ppi after we've done cropping (ignoring software interpolation) Couldn't the 18MP "get closer" to the subject since it can crop in tighter to get that 300ppi?

To me this would appear to counter the "higher MP's dont matter etc... for small prints" since you've just added to your lenses possible focal range.

Again I'm new, not trying to argue, just understand the downplaying of the MPs I often see.

 

[clanthar]

Your logic is fine; all other things being equal more resolution is going to be an advantage over less. The ability to crop an image and still retain enough detail for a good photo is one obvious example. Like anything else it's a cost/benefit equation. All things being equal I'd do all my shooting with a Hasselblad H4D-60 (about $45,000.00 with a couple lenses) -- the 60 means 60 megapixels. Having done the cost/benefit analysis with my dear wife looking over my shoulder has left me with a different camera and a happy marriage.

It's that "all things being equal" catch that you have to look at carefully when making a final choice -- all things aren't equal. More megapixels and a poorer lens won't get you ahead, etc.

Joe

 

[ClickAddict]

You are right. What you have to realize though 18mp is not a huge jump from 12mp. Just based on the # it looks like a huge jump, but its not. 18MP is actually only 22% wider.
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Thanks. That 22% is the number I was curious about. So yeah 22% would probably not be a fairly large factor. And obviously I was comparing fairly close MP. Cause I know there wasn't anyone here who would argue the advatages of a 60mp Hasselblad vs some 6MP.

 

[enzodm]

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Thanks. That 22% is the number I was curious about. [/QUOTE]

1.22 ≈ sqrt(18/12) (=122%)

sqrt(60/6) ≈ 3.2 (=3 times wider). If in front there is a plastic mobile phone lens, not much gain. If sensor size is the same, dynamic range will be some times tighter (i.e. less real color shades).

 

[KmH]

Pixel pitch and pixel size will also be factors.

Canon packs 18 MP onto the smallest APS-C size senor widely available today (22.3 x 14.9 mm), while Nikon elects to only pack 16 MP onto a somewhat larger 23.6 x 15.6mm image sensor.

Note the differences in several measures of Raw image quality performance as measured by an independent testing lab. Also note the difference in the cost of the 2 cameras: DxOMark - Compare sensors