I think this is a new feature on the 500px site. When viewing a photo you can press Details on the right hand side and see the exif. The new feature now is that there is a link that lets you search the website for photos taken with the same camera.
Here is a link to search for photos taken with K-01, for example:
Pentax K-01 / 500px
The feature seems to be in partnership with amazon, as it also shows a link to "purchase this camera"
Its interesting for us Pentaxians, as we can now find each other more easily. And new customers have one more resource to research what a camera is capable of.
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