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Scenario:

I take a picture with a camera that has a crop factor of 3.19. I use a 55 mm focal length equivalent for taking the photo. In the resulting image file header, it says a magnification of 0.17.

I guess what is confusing me is when someone asks for ‘pixel size after taking the magnification due to relay optics into account’ and then also asks for the objective lens magnification I am not sure how to interpret these questions. My pixel size on my sensor is 1.4 um.

Camera model: Lytro Illum

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I'm not clear on your question.

I note that a 55mm equivalent divided by a 3.19 crop factor suggests a 17mm lens.

Pixels don't have sizes. Sensors have sizes, and pixels can be presented as pixels per inch as a function of your print or display. Pixels may even be referred to as having a size derived from how they are constructed from the sensors, but in general pixels alone have no intrinsic size.

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    The pixels on a sensor absolutely definitely do have a size. – Philip Kendall♦ Apr 2 '20 at 7:56
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    @Philip Kendall - There are no pixels on a sensor. Pixels are software constructed from a combination of sensors. Multiple monochromatic sensors are used to create a single color pixel. However it's not a simple divisor effect as any given sensor contributes to the creation of multiple pixels. Pixels are mathematical constructs of physical sensors. – user10216038 Apr 2 '20 at 20:21
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    @Philip Kendall - This article is rather dated but it's still worth reading: alvyray.com/Memos/CG/Microsoft/6_pixel.pdf . The confusion comes from overloading of terms. Many sources do refer to pixels on sensors, but these are really sensor elements on sensor arrays, not pixels. For most common usage the difference is arguably unimportant, but since a pixel can be computed multiple different ways from individual sensor elements, there is no fixed physical size of a pixel. – user10216038 Apr 2 '20 at 20:50
  • @user10216038 it might be helpful to clarify that image pixels do not have dimensions. Many folks use photosite, sensor element, and pixel well interchangeably. – Michael C Apr 5 '20 at 8:39
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Pixel sizes are anywhere from 1 to 10+ microns in size and the size and the way they are configured/positioned compared to one another determines their light-gathering abilities. Cramming too many pixels on to a sensor may make it sound like you have a high megapixel (millions of pixels) camera but it was misleading. Improvements in processors over the years have enabled the camera makers to balance quality and the size of the pixels. My old D-50 Nikon had 7-micron size pixels and my later D-90 had 4-micron size as well as the D7100. Each successive camera has better noise capabilities. Hope this helps.

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  • What you are describing is sensors not pixels. – user10216038 Apr 2 '20 at 20:23
  • More specifically, sensor elements on sensor arrays. – user10216038 Apr 2 '20 at 20:56
  • @user10216038 It's pretty common to refer to photosites or sensor elements as pixel wells or even pixels. Even the correct term sensel is a mashup of sensor + pixel. – Michael C Apr 5 '20 at 8:41

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