A question about DX vs FX when it comes to resolution.

[ProfJohn]

Ok, was looking at the Nikon web site at the D700 and D90

Both cameras have the same number of megapixels, but one is DX and one is FX

Since the DX has a smaller frame size wouldn't that mean that is pixels are closer together and thus the camera would have better resolution?

The FX has the same number of pixels, but they have to cover more area and thus each one would have to be 'bigger'

 

[IronWing]

Using the same exact lens, distance to scene, and focal length (if a zoom lens) on both cameras, then yes, the DX would have a higher resolution for that portion of the full scene it captured as parts of the scene are cropped and the part of the scene remaining would be chopped up into more pixels with the DX than the corresponding portion of the full scene captured by the FX sensor.

Edit: If you use a DX format lens on the DX camera and an FX lens on the FX camera with identical focal length and distance to scene then the resolution would be nearly identical as there would be no crop factor.

 

[fuzzybabybunny]

Two sensors with the same number of pixels, but one is larger and the other smaller. The smaller one would have a higher concentration of pixels and they would have to be of a physically smaller size. The larger one would have a lower concentration and the pixels (photos sites) can be bigger. Since they are physically bigger, they are able to record a broader dynamic range (brightness range) and respond with less noise when amplified to higher ISOs.

 

[jpeyton]

A spec that is never included by the manufacturer on the box, but definitely makes a difference, is the physical size of the pixels on the sensor. D700 images are sharper and cleaner per pixel than D90 images, although it's hard to tell in prints or on the web without looking at 100% crops.

D700 files can also be pushed a lot more than D90 files without showing degradation. This is especially evident when I compared HDR images made with the D90 vs. the D700.

 

[ElFenix]

Using the same exact lens, distance to scene, and focal length (if a zoom lens) on both cameras, then yes, the DX would have a higher resolution for that portion of the full scene it captured as parts of the scene are cropped and the part of the scene remaining would be chopped up into more pixels with the DX than the corresponding portion of the full scene captured by the FX sensor.

Edit: If you use a DX format lens on the DX camera and an FX lens on the FX camera with identical focal length and distance to scene then the resolution would be nearly identical as there would be no crop factor.

you mean identical fov. focal length is focal length regardless of what you stick behind the lens.

if you use a lens set at ~1 1/4 stops slower on the 35mm camera than on the crop camera (assuming nikon, ~1 1/3 stops for canon, 2 stops for 4/3), you'll get fairly identical dof too.

the ability of crop cameras to put more pixels on a subject has its advantages for birders. the 7D can get more pixels on a subject than any other SLR, including the 4/3 cameras, using identical focal lengths.

so, for the OP, if you were to shoot at a dollar bill or a dictionary page with the D90, then take that same lens and shoot from the same place with the D700, the D90 will be more legible (assuming good light)

 

[finbarqs]

from what has been taught to me, consider that each pixel are "light buckets". The bigger the bucket, the more light it can capture! So no, higher pixel density does not translate to "sharper" images, but simply just "more" resolution. What does more resolution give you? Bigger prints. That's all.

However, bigger resolution has it's drawbacks: Light diffraction. There's a whole entire course on how light can diffract on higher pixel density as opposed to a smaller pixel density, and you can read all about it here:

http://www.digitalpixels.net/2009/07/photography/diffraction-in-photography/

In addition, the higher your resolution is, the likelihood that your sensor will out resolve your lens, giving you soft images. Thus, high quality lenses (you determine this with MTF charts) are required for higher resolution cameras.

If I had a perfect camera, it would be a 8-10MP camera (since my largest print is a 16x20) FF sensor camera.

 

[Madwand1]

Since the DX has a smaller frame size wouldn't that mean that is pixels are closer together and thus the camera would have better resolution?

By this reasoning, the way to get the highest-resolution camera is to get the greatest number of (mega) pixels in the smallest sensor. While this is what the average consumer does, the reasoning is obviously flawed as it leads to incorrect conclusions.

 

[soydios]

Ok, was looking at the Nikon web site at the D700 and D90

Both cameras have the same number of megapixels, but one is DX and one is FX

Since the DX has a smaller frame size wouldn't that mean that is pixels are closer together and thus the camera would have better resolution?

The FX has the same number of pixels, but they have to cover more area and thus each one would have to be 'bigger'

Resolution is a function of the entire imaging system, from the lens focal length, lens aperture, sensor anti-aliasing filter, sensor pixel density, software Bayer interpolation, and shooting platform stability (handheld, tripod, mirror lockup, etc.).

All that a sensor with a lot of pixels in a small size means is that it has a high pixel density. Resolution is the angle subtended by each pixel (aka number of pixels on target), assuming that everything else is perfect.