One of the fun things we are showing at NAB is a set of prototype Kish Lenses. This post goes into some more details about the lenses, their look, and the quality testing.
Review: (You can skip this paragraph if you already know the lens specs) The three lenses we have made are super 16mm primes in the focal lengths: 10mm, 18mm, and 38mm. The lenses are fixed focus and fixed aperture. The lenses are set to f4 and intended for indoor use. They will be able to focus on our Universal C-Mount Follow Focus Mount, which moves the lenses toward and away from the sensor on an electronically controlled rail system, that will be controlled by the crank on the side of the camera.
Let's talk about the design and look of the lenses a bit first.
These lenses are designed after the style of the unique high quality prime lenses of the 60's and 70's. Modern lenses have twice as many elements as vintage glass, and modern lenses use special coatings to create clarity on sometimes lower quality elements, even plastic internal elements. Our lenses have a minimilist design theory only using 4 - 5 elements, and all elements are glass. We are using the shape of the glass to create the look and sharpness and not relying on coatings. We are using modern coatings on some elements. The front element, and the rear element both have modern multi-coatings on them, but all of the interior facing elements have no coatings at all. That means that when you point them at lights you get these cool lens flares that give you a great vintage look and are so hard to get on most modern lenses because of their coatings.
The real quality of vintage lenses is not the lens flare though, it's the tight sharp feel you get, while still being flattering to people and skin.
So after 4 different lens tests and a lot of tweaking we are ready to show you some prototype lens images.
The 10mm and the 18mm are both performing up to the standards we were expecting, but the 38mm is quite a bit softer than we expected over the whole of the image. This indicates there is either something fundamentally wrong with the design, or there is a problem with the manufacturing of the samples. We are getting some more samples from our manufacturer to help us figure out which problem it is.
Keep in mind these are prototypes, that being said we are pretty proud of where we are so far with the lenses.
When we first got the lenses in we brought them over to Otto Nemenz, the guys there were very kind to agree to help us test them. In order to test lenses you need a very fancy projector.
We then ran into our second problem, we couldn't get the lenses to focus properly the way they were supposed to.
We discovered that due to a miscommunication our optics designer had compensated the Flange Focal Distance on the lenses to compensate for the optical block in the camera, but this was unnecessary since the camera mount compensates for this.
Through a lot of very precise negotiation we eventually got the images into focus. The first thing we found was that the image circle of all three lenses is really big! These lenses will come really close to completely covering M43. The larger "TV SAFE" format is full frame 35mm!
We left Otto Nemenz with a lot of good information, but I wanted to test the lenses on a camera, even though they weren't really ready yet. Wide Open Camera offered to setup a test with a GH2 and below is what came of this test. Keep in mind these are made with the still incorrect FFD.
I felt the detail and look of both the working Kish lenses out performed the more expensive Panasonic one.
After some testing we discovered that one of the elements on the 38mm was backwards. This and the improper FFD meant a trip to the machine shop.
We had the back of the lenses ground down to allow for the proper FFD, but it would mean shimming the lenses again.
This time we took a trip out to Schneider Optics who were again very gracious to let us test there. We setup the lenses on a projector and started testing the focus.
After we found all of the right shim distances we assembled the lenses with shims in place.
The 38mm got better with the machining but was still not at the performance level of the other two.
I really wanted to see what these would do with skin though, so we went back and shot these lens tests.
I put crop marks on the pictures so you can see the actual active area for M43 and for S16.
The result we think is pretty good! There is some color issues in the 10mm we are hoping to deal with a little, and the better, but still obvious fogging in the 38mm, and very tiny amount of very diffused vignetting on the 18mm. I actually kind of like the vignetting on the 18mm and it turned out to be my favorite of the lenses. I know a lot of people want the wide, but I really like the 18mm. I also thought the depth on the 38mm was really nice if we can deal with the fogging issue.
We showed the lenses to lots of people already and the response has been very positive. They are going to give you a look and a way of working that just doesn't exist in modern lenses.
We are very interested to hear what you guys think, if you're at NAB please come by today or tomorrow to see the camera and the lenses, we are at the Pomfort booth #C8441