105mm f0.75: too ‘bokehlicious’ to be true?


During a recent web session I stumbled across this article on Petapixel, about photographer Jason Ahrns and the curious 105mm f/0.75 lens made by Dutch optics manufacturer “De Oude Delft”. When researching polar lights for his dissertation, Ahrns discovered that lens in one of the storage cabinets of the research group he is working with. Since such lenses, based on experience, require a short flange back distance, he disassembled a NEX3 in order to get the rear side of the lens closer to the sensor. Sadly, the poor NEX did not survive the “moding” 😛 So, Ahrns had no other choice than to try his D610 in Liveview mode. But even that turned out to be problematic, since the huge lens comes with neither focus ring nor mount and can therefore neither be connected to the camera nor properly focused. In order to move the focus area, the entire lens had to be moved back and forth, while the back of the lens extended very, very far into the mirror box of the DSLR. Sounds like a great way to scratch the sensor? It is! But the things we do in the name of “bokehliciousness”… 😉

Big lens

© Jason Ahrns

But the missing focus ring is by far not the only problem with this lens. As it turned out, as with many speciality lenses the focus area is very limited. Commenters on the Petapixel article are speculating that it is a lens for x-ray images which usually have lens designs optimized for close range. Such lenses cannot focus on subjects further away without an adapter with corrective lenses on the back of the lens, since the sensor would have to be in the middle of the lens. Hence the moral of the story – if a lens is too “bokehlicious” to be true, you should always ask where the catch is. 😉

Here is a photo Ahrns took using the lens:

Leaves and berries

© Jason Ahrns

It’s a real shame that you cannot take portraits with it.

  1. […] 105mm f/0.75 produced by the Dutch optics manufacturers De Oude Delft, which I’ve written about here. One additional extremely fast lens I’d like to introduce you to today, is the IRTAL Super-Fast […]


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