crops

For a newcomer to photography, can somebody explain what is meant by say a 100% crop or a 50% crop , how do these figures relate to the original taken with a K10D.
Thanks.

The term '100% crop' is a bit misleading, and it was a while before I realised what people were on about too.

It actually means 'a crop, where 100% of the original pixels are shown'.

If you consider the K10D frame, it's 3872 pixels wide and 2592 pixels high, which is way too big to show in a browser. So the original needs resizing - to 800 pixels wide, for instance, for the weekly competition here.

So inevitably, pixels are lost in the process.

This has a number of consequences, one of which is that it's almost impossible to tell anything meaningful about the sharpness, or the noisiness of the original image.

So what people tend to do, in order to show these meaningfully on a web page, is crop out just part of the image, so that it displays at its full resolution on the page.

So you get to see 100% of the pixels from that part of the image.

Hope that helps!

Here's an example. This is the whole frame, taken with a lens I recently bought, resized so that it fits nicely in the browser.




Here's a 100% crop of part of it:

Well explained Chris! The only thing I would add to that, regarding 50% crops and the like, is that this would probably mean that the image has been cropped to 50% of its original size (regardless of any resizing to fit on a webpage).

So for that 3872 pixels wide and 2592 pixels high K10D image, it might have been cropped down to 2700 x 1800, which would be roughly half the pixels of the original. This would be to crop out distractions, or just concentrate more on the subject.

For instance, this image:




I would say cropped to 25% (rather than 25% crop, to avoid confusion with the 100% crop thing), so the file that looks like this image was about 1500 x 1000 pixels (from my 6mp, 3008 x 2008, *istD). It's then been resized for the web.

Hope that helps,
Dan

To put it another way:

A 100% crop means a non-resized crop.

Many thanks for the replies, i think that explains it for me.