What do you guys mean by 100% crop?

??? I've seen it mentioned in this forum but I need someone to 'splain' what it means.

It is a crop of a portion of an original image that has not been itself resized.

Imagine printing the picture, full size, on paper. Then take scissors and manually crop a section out.

That cropped section is a 100% crop since has not been enlarged or shrunk after being isolated from the original. It still fits perfectly into the place it came from.

Extrapolate back to a computer display and you've got it.

View at Actual Pixels, or 100%, so that 1 pixel on the monitor shows 1 pixel from the camera sensor.

That is when you open your photo in Photoshop, zoom to 100% (which usually means you will not be able to see the entire shot, only a portion of it), then using the rectangle selection tool, select an area, then crop away every thing other than the selection. For the purpose of posting here, you want the selection to have a longest dimension of no more than 800 pixels.

The resulting image is a 100% crop. Because 1) it is at 100% zoom, and 2) it is a cropped portion of a larger shot.

When you post that, the primary purpose is to show sharpness (or lack of sharpness), or to draw attention to a certain area of a shot. It is not usually meant to be a final image for printing.

In THIS POST, the lower shot is a 100% crop.

Rad