There are perks to doing your PhD on optical studies of the aurora, and among them is that you might just stumble across a very exotic lens like the De Oude Delft 105mm f/0.75 in the cabinets of the research group you’re working with.

That’s what happen to photographer Jason Ahrns, and although they wouldn’t let him buy the lens, he was allowed to take it home on an extended loan and try to put this monster through its paces.

The lens reminded Jason of this 50mm f/0.75 X-Ray lens we featured, but he’s uncertain if the 105mm is an aerial reconnaissance lens or an X-Ray lens. Whatever the case, it seems to be locked to infinity focus by default, but the sensor has to be a few millimeters behind the rear element to achieve it.

Needless to say, this is no easy feat. Initially, Jason tried to take apart an old NEX-3 and retrofit it onto the lens by custom-building an adapter. Unfortunately, he actually ended up breaking it before he could remove enough parts… oops.

And so he switched techniques. Using his D610, he was able to ‘freelens’ with this beastly lens using live view, getting close enough to the rear element to focus about 2 feet away.

Here are a few behind the scenes photos taken by his friend and fellow photographer Andrew Winkelman:

By using this technique, he was actually able to capture a few very ‘dreamy’ looking soft focus images of some tree branches with berries he collected from outside and — rest in pieces — the loose parts from his NEX:

Jason could find precious little information about this lens, so if you can enlighten us all on its original use and why it’s built the way it is, definitely drop us a line in the comments.

And if you’d like to see the sample shots, bts shots, and images of the lens in full res, head over to Jason’s Flickr photostream by clicking here.

Image credits: Photographs by Jason Ahrns and used with permission