Kowa 65mm f/0.75 X-Ray Lens Mounted on a Nikon D90
Every now and then I see something so unique that is makes me want to try it. As it stands the fastest lens that I have ever seen would be The Leica’s Noctilux-M 50mm f/0.95. It stands to reason that this lens is very unique and would lend itself to being something you don’t see every day.
Flickr member scenery_and_fish found a Kowa 65mm f/0.75 x-ray lens, and mounted it to a Nikon D90 using a macro extension tube and epoxy. The plus side obviously is that it is a .75 lens and for those of us that Know photography, “That’s FAST”! Ok now for the down side…the lens is fixed focus and lacks an iris.
While it would be fun to note that this would be a good lens to play with I would have to say it is more like a side show attraction at a circus in the end. The fact that the lens lacks the ability to focus is a big turn issue in of itself. I can live with the all the down falls accept this one. One work around might be using the lens on a macro slide rail type setup. While bulky it would give the lens the ability to focus..
Another key problenm to point out is the fact the lens an issue which appears to be bad spherical aberration, which makes sense. The faster a lens is, the harder it is to correct for aberrations. The only way to make an ultra-fast lens like this one work is to design it for a fixed magnification, e.g. 1/25 life size, which might be appropriate for chest x-rays. As you move away from the designed magnification, the aberrations will get worse. By the time you get close to life size, the aberrations will be bad enough to make the picture very soft. Combine that with ultra-narrow DOF from the fast lens and high magnification, and you get a soft in focus image and everything out of focus blurred into a smear.
Maybe In the end it is a big lens that will win any war in it’s ability to gather light but alas that would be the only war it would win.
Check out his Flickr photo stream for a gallery dedicated to to this setup. He definitely has some interesting pictures.