Impossible to tell. Without even knowing the camera used, there's no way of even guessing the lens & aperture. It might even be a result of post processing.
BTW, posting images that you have no rights to post is a violation of forum rules.
As said we prefer users to link to reference material rather than post photos to the site as attachments which they do not own.
That said from what I saw of the pictures the only guide you can get from them is that the out of focus highlights have a ring/doughnut shape to them. This can be commonly the result of using a "mirror" lens. These are typically long focal length (500mm) and small lenses which allow for their long focal length and light weight by using a mirror assembly - as a downside they create the doughnut rings in backgrounds as opposed to complete circles that normal lenses do. This is generally seen as a downside so there are not many mirror lenses around.
The pictures were taken with a Nikon and a manual lens. Sorry if I'm posting these pictures, maybe I can delete them when thread is closed? There are just here for illustration purpose. Where can I find these "mirror" lenses?
The pictures were taken with a Nikon and a manual lens. Sorry if I'm posting these pictures, maybe I can delete them when thread is closed? There are just here for illustration purpose. Where can I find these "mirror" lenses?