hi:

1. i just read the article "do sensors outresolve lens?" and have a question; hopefully someone will shed some light on this.

2. via table 3, the author noted "Consider a 35mm system with a lens at f/11. At best, the maximum resolution you will get is equivalent to 16 MP, even if your camera has 22 or 25 MP." Looking at that table, if one were to close the lens down to f22, then supposedly one would achieve the resolution equivalent to a 4MP sensor.

3. issue: even though one would supposedly come away with a 4MP resolution image (if one were to shoot at f22, using a 35mm sensor), i assuming the file size would be such that one would be able to print a large print (ex: 13 x 19 @ 300 ppi) without interpolation. i understand that if one were to shoot the same image at f8, the resolution of the image would be improved based on the reasons noted via the article.
my question is i'm assuming that with the above being said, is it still of benefit to shoot with the above theoretical camera compared to using a 8MP camera, shooting at f8--> achieving a 4MP resolution and then having to interpolate up inorder to print the same sized 13 x 19 print?

4. hopefully the above makes sense. thanks for the info. harry shin

I believe the concept here is that a doubling of f stop values from F11 to F22, halves the resolution of the lens, provided the lens is completely diffraction limited at both of those f stops.

Conversely, quadrupling the pixel count from 4mp to 16mp doubles the (potential) resolution of the sensor.

Therefore, doubling the resolution in the sensor, coupled with a halving of resolution from the lens, is equivalent to doubling the resolution from the lens coupled with halving the resolution in the sensor.

In practice, I suspect this is only a rough approximation.

The print size possible without interpolation depends only on the number of pixels, not the sharpness of the pixels.

A 4mp 35mm image taken at F11, interpolated to 16mp, should have roughly the same resolution on print as the uninterpolated 16mp 35mm shot taken at F22, but my guess is the interpolated 4mp image would have slightly less resolution in practice.

Not to nitpick, but f/11 to f/22 is 1/4 of the value. f/11 to f/16 is 1/2.

Mike.

Missed it! Just shows how tired you can get sitting reading off a screen.

Rob C

I will try to help a bit Harry.

2. In the Table 3, in the f/11 row, 35mm column, w=0,55 subcolumn, you can see 16, this is, 16 MP. This number comes from the size of the Airy Disk of a diffraction limited lens at f/11. Then, we add two pixels per Airy disk diameter. The resulting contrast of the final image will depend on Airy disk separation. For f/22 you get 4MP.

3. The key for a correct understanding of this point is the difference between image size (in pixels) and the real detail captured. The image size is like a bottle. You can fill it with more or less detail (water). The point is: you get the same water with a smaller bottle full ad with a larger bottle only partially filled. You can interpolate the smaller image (in pixels) and preserve the original detail, but this largely depends on the interpolation software. Interpolation only determines the final size of the bottle.

I was referring to numerical values. Within f stop ranges that are defraction limited, a doubling of the f stop 'numerical' value results in a halving of resolution in terms of lp/mm at a specific contrast. Why did you think I was referring to exposure?