There is a helmet at the Polish Army Museum in Warsaw that they placed with objects belonging to first half of the 16th century -
http://io.ua/04983864

it looks like a Turkish or Balkan production, although most likely was used by the Polish or Hungarian or Serbian hussars of that period, with coat-of-mail and steel round shield - but one of the members at the Polish site historycy.org sugested that this helmet could be of the Muscovite production of 16th century.

I think this is Turkish (with parts added later) or generally Balkan, however it might be also form Nuremberg workshops?

Please see the part of the exhibit where you can find this helmet (on the far right) dispalyed
http://io.ua/04983863

any opinion would be appreciated

It's aesthetically reminiscent of early Slavic spangenhelms with it's pointed dome, it's interesting to see how regional tastes tend not to change much over the centuries.

The photograph is not detailed enough to make out one of the chief ways of distinguishing between Islamic and non-Islamic pieces. Islamic pieces often have genuine Arabic inscriptions, but non-Islamic pieces fake it.

Hi,
I would guess Russian/Turkish Shishak 16th Century.
Regards,
Norman.