There is way. Take for example this link - https://500px.com/photo/116503325/nastya-by-Георгий-Чернядьев-georgy-chernyadyev-
If you are using Chrome,
1) right click somewhere near the photo, last item in context menu - Open a feedback form (Ctrl + Shift + i), for example lets click a litle bit below inscription "500px"
2) in opened meny look for "<div id="content">..." open it by clicking on triangle to the left
3) in submenu "<div class="photos_index_layout"" look for "<div class="main_container">" and open it (triangle)
4) there you will find <div class="photo_container", after opening it you will see next line:
"<img class="photo" style="display: inline; margin-top: 0px; width: auto; height: auto;" src="https://drscdn.500px.org/photo/116503325/q%3D80_m%3D2000/b345dcc1bcb8cabf291a11d335ebbcbc" alt="Nastya by Георгий Чернядьев (Georgy Chernyadyev) on 500px">"
5) just take URL from that line and paste it in new Chrome window - https://drscdn.500px.org/photo/116503325/q%3D80_m%3D2000/b345dcc1bcb8cabf291a11d335ebbcbc
now you can save the photo
It will be much easier after you tried to do that for few times)