All this talk about "equivalence" is silly

Started Jun 10, 2011 | Discussions thread
Great Bustard Forum Pro • Posts: 40,847
The source of the confusion

carlk wrote:

Eaxactly. It's just a crop factor.

This is clearly explained in the Equivalence Essay immediately after the introduction:

h ttp: www.josephjamesphotography.com/equivalence/#superduperquick

  • Equivalence is a framework for comparing the IQ of different formats on the basis of five parameters (perspective, framing, DOF, shutter speed, and display size), which all directly relate to the visual properties of the final photo, and are independent of the technology. In addition, the same amount of light will fall on the sensor for Equivalent photos, which will result in the same image noise for equally efficient sensors.

  • Consider two cameras with sensors that had the same efficiency and pixel density, but one with a sensor twice the size (four times the area) as the other. If we were to shoot the same scene with each camera from the same position, using the same lens and camera settings, crop the middle 25% of the photo from the camera with the larger sensor, then the resulting photo would look exactly the same as the photo from the smaller sensor camera if displayed at the same size.

  • Alternatively, if the sensors had the same efficiency and same number of pixels, but the larger sensor camera used a perfect 2x TC (teleconverter) with the same lens used on the smaller sensor camera, and shot the same scene from the same position with the twice the f-ratio and two stops higher ISO, then the resulting photos from the two cameras would be exactly the same.

The eauivalence theory has confused the heck of the bigginers. By begginer I think a lot of posters express opinins in this thread seem to fit that description.

It's not Equivalence that has "confused the heck of the beginners", but those who incorrectly represent what Equivalence actually says that has caused the problems.

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