The Hermitage has a nice exhibit featuring helmets from the 15th-17th centuries:

http://www.hermitagemuseum.org/html_En/12/2004/hm12_2_11.html

The link above takes you to 11 examples, all of which are viewable in 360 degrees (!) and with photos of special details. The "metal work" link at the top of the page will take you to more detailed images.

I was at the hermitage earlier this year and my guide said that they were considering putting more of the arms and armour collection on display. What they are showing is about 3% of what they own... looking forward to that if they do. Some truly amazing pieces there.