Real resolution differences between cameras

[bgbs]

If you take a 36mp camera (D800) and put it against 22mp camera (5DIII) and run simple high-school math, what you get is that a 36mp is 39% larger in terms of resolution than a 22mp sensor. But that is not the case according to some experts. They claim that the difference is much smaller, like 15% or some such number. My question is, how do you calculate a REAL resolution difference between camera sensors? Can someone, perhaps, point me to an article that explains that in greater detail?

 

[photoguy99]

Can you cite these experts?

Possibly they are talking about linear resolution, dots per inch. That seems like it would come out about right.

To compare cameras this way take square roots of the megapixel counts, and compare those.

 

[bgbs]

Can you cite these experts?

Possibly they are talking about linear resolution, dots per inch. That seems like it would come out about right.

To compare cameras this way take square roots of the megapixel counts, and compare those.

For example Thom Hogan: Re: Line vs area: Nikon FX SLR (DF, D1-D4, D600-D800) Talk Forum: Digital Photography Review

 

[photoguy99]

Yup. It's linear resolution versus area resolution.

Take square roots of the megapixels and compare those.

 

[bgbs]

I'm struggling to understand why linear resolution is important in terms of actual image resolution. Is linear resolution basically what counts in what the actual detail resolution of the image is?

 

[photoguy99]

Yep. Linear resolution is much closer to e what we see as 'sharpness' or 'clearness'

 

[robbins.photo]

I'm struggling to understand why linear resolution is important in terms of actual image resolution. Is linear resolution basically what counts in what the actual detail resolution of the image is?

Well, considering that the numbers themselves don't really translate to what you can perceive I guess I've always thought of it as being a moot point. Take a shot with a D800 and a 5DIII under most conditions and view it on a computer screen and it will be difficult to impossible to tell the difference. One won't be 39% better, clearer or sharper than the other, in fact they will most likely appear almost identical.

Higher resolution does come into play when your cropping a shot and I suppose it might matter if your printing something huge, but really in my experience under most circumstances you'll be hard pressed to tell the differences in resolution just be looking at the final product.

I know a couple of guys that shoot portraits and one of them tells me he actually prefers to use a lower resolution camera when he can, I guess for a lot of folks a really high resolution shot can cause some issues because it tends to highlight imperfections that a lower resolution shot won't. I can't speak from experience on this one myself, I don't shoot portrait often (rarely if ever really) - but it is something I've heard from a couple of guys who do shoot them regularly.

 

[runnah]

Megapixels refers to 1 million pixels in an given image. so say you have a 10mp camera, the images will have 10 million pixels (not exactly 10 million but near enough). And so on.

So say I take my 5d mkIII which has 21.1 megapixels. This produces a 5,616 × 3,744 pixels image. Multiple those two numbers and you get 21,026,304 or rounded up 21.1 megapixels.

The image height and width is defined by the aspect ratio. For an example, your standard HD tv is 16:9, older SD tvs were 4:3. The base number of pixels doesn't change, just the HxW measurements. So if I took the above numbers 5,616 x 3,744, and shot the same MP camera at a 1:1 ratio the dimensions would be 4585 x 4585.

Make sense?

 

[qleak]

I'm struggling to understand why linear resolution is important in terms of actual image resolution. Is linear resolution basically what counts in what the actual detail resolution of the image is?

C'mon linear resolution is used all the time in photography. Consider the following:

• multiply an f-number by 1.4 to decrease the aperture by a stop
  
• move a light source 1.4 times it's distance away to decrease the amount of light on a subject by one stop

1.4 is approximately the square root of 2. It's all there in the inverse square law and the classical mathematical doubling problem.

How do you double the area of a rectangle but keep it in a similar shape? Multiply the side lengths by ~1.4

So linear resolution is how tightly the pixels can be put in a line and area resolution is the total number of pixels.

 

[bgbs]

I guess I'm starting to get it. To double the resolution you need to times it by four not two when dealing with actual pixels. Say, a 16mp camera is double the resolution of a 4mp camera in terms of linear resolution. A 36 mp is approximately 55% more resolution than a 16mp sensor.

 

[qleak]

I guess I'm starting to get it. To double the resolution you need to times it by four not two when dealing with actual pixels. Say, a 16mp camera is double the resolution of a 4mp camera in terms of linear resolution. A 36 mp is approximately 55% more resolution than a 16mp sensor.

FYI:
Unless it's markup (which is screwy). Percent difference is calculated 100*(new - original)/original

so if by resolution you mean the number of pixels, (36-16)/16=1.25 so the 36MP has 125% more pixels than the 16MP camera.

But the linear difference is less sqrt(36)=6 sqrt(16)=4 so (6-4)/4=.50. So the 36MP camera has 50% more linear resolution than the 16MP camera.

 

[Ilovemycam]

If you take a 36mp camera (D800) and put it against 22mp camera (5DIII) and run simple high-school math, what you get is that a 36mp is 39% larger in terms of resolution than a 22mp sensor. But that is not the case according to some experts. They claim that the difference is much smaller, like 15% or some such number. My question is, how do you calculate a REAL resolution difference between camera sensors? Can someone, perhaps, point me to an article that explains that in greater detail?

You can't go by numbers. Numbers are for camera fondlers. Fuji 16 mp crop is in ballpark with Leica FF 24mp. The numbers are not close, but real life shooting does not go by numbers.

Camera Comparisons

 

[runnah]

You guys are way off. A megapixel is a defined value.

The difference between a full frame sensor and a cropped sensor is the pixel density. A 16mp ff and crop sensors is going to have the same number of pixels, just the crop sensor will be more tightly packed together.

 

[pixmedic]

obviously the difference between a 36mp camera and a 21mp camera is 15mp. duh.
you don't need differential calculus and a Ouija board to figure that out.

 

[runnah]

obviously the difference between a 36mp camera and a 21mp camera is 15mp. duh.
you don't need differential calculus and a Ouija board to figure that out.

It's really very simple