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I wonder what taking a digital photo "at 20x magnification" actually means. Magnification implies a conversion factor between two comparable objects. There's no

I wonder what taking a digital photo "at 20x magnification" actually means. Magnification implies a conversion factor between two comparable objects. There's no sensible comparison between an object 8 inches across and a digital image of that object 5000 pixels across.

Retric 12y ago
It's more obvious at the extremes. At 20,000x magnification your going to show a lot of details normally missed. A high resolution close up shot will often have less detail and than the same number of pixels using some magnification.
- Retric 12y ago
  I guess I did not get my point across aka not all pixels are equivalent. A camera such as a cellphone camera is designed to take a fairly wide angle picture. It also has a minimum distance it needs to be from an object so moving your finger closer to the sensor stops providing more detail at some point and just provides a blurry mess. Adding a magnifying lens between the camera and the subject allows you to get more details at the same distance by sacrificing that wide field of view. With the right setup it also allows for higher detailed pictures of the same object aka more details than you would get at the minimum distance for a clear picture. So that 20x zoom refers to the physical optical zoom. You can try this by comparing the highest detailed picture of your hand from your cellphone with and without a magnifing glass.
twic 12y ago
The digital photo is captured using a physical sensor. It is meaningful to talk about the ratio of the size of the object, and the size of the image formed on the sensor - this is called the reproduction ratio. It's as relevant now as it was back when images were captured on film and then blown up onto prints. It is the combination of the reproduction ratio and the resolution of the sensor (in pixels per unit distance on the sensor) which determines the resolution of the image (in pixels per unit distance on the object). That said, it's not clear that this is what is meant here.
mcguire 12y ago
It likely means that they took a photomicrograph through a 20x lens using the highest resolution camera they had handy.

Retric 12y ago

It's more obvious at the extremes. At 20,000x magnification your going to show a lot of details normally missed. A high resolution close up shot will often have less detail and than the same number of pixels using some magnification.

Retric 12y ago
I guess I did not get my point across aka not all pixels are equivalent. A camera such as a cellphone camera is designed to take a fairly wide angle picture. It also has a minimum distance it needs to be from an object so moving your finger closer to the sensor stops providing more detail at some point and just provides a blurry mess. Adding a magnifying lens between the camera and the subject allows you to get more details at the same distance by sacrificing that wide field of view. With the right setup it also allows for higher detailed pictures of the same object aka more details than you would get at the minimum distance for a clear picture. So that 20x zoom refers to the physical optical zoom. You can try this by comparing the highest detailed picture of your hand from your cellphone with and without a magnifing glass.

twic 12y ago

The digital photo is captured using a physical sensor. It is meaningful to talk about the ratio of the size of the object, and the size of the image formed on the sensor - this is called the reproduction ratio. It's as relevant now as it was back when images were captured on film and then blown up onto prints. It is the combination of the reproduction ratio and the resolution of the sensor (in pixels per unit distance on the sensor) which determines the resolution of the image (in pixels per unit distance on the object). That said, it's not clear that this is what is meant here.

mcguire 12y ago

It likely means that they took a photomicrograph through a 20x lens using the highest resolution camera they had handy.