Preconceptions

I try to start these articles by putting my preconceptions out there first. Every reviewer or blogger has them, they affect our opinions, and you have a right to know them. So I’m writing this introduction the day before our first copies arrive.

The HandeVision IBELUX 40mm f/0.85 is designed by IB/E Optics GmbH in Germany and manufactured by Kipon (aka Shanghai Transvision Photographic Equipment Co. Ltd). IB/E has developed a number of lenses and adapters for the Cinema world and other optics, so I figured the design would be good; probably a telecentric lens with a built-in Speedbooster-type element or group. Kipon is known as a lens adapter company, although Shanghai Transvision has also manufactured and distributed video and photo accessories. They are rumored to manufacture lenses for other brand names, so they have some lens manufacturing experience. But, I have to say, my expectations for build quality weren’t great. I expected a lot of variation between copies. I don’t know if I even had any expectations regarding image quality.

Okay, so much for what I expected. There are now five new copies sitting on my desk so let’s take a look.

Look and Feel

I can guarantee that you’ll see “built like a tank” posts all over the forums when people start handling this lens. Why? Because people say “built like a tank” when anything is really heavy, and this lens is really heavy at 2.65 pounds. (To put it in perspective, a Canon 70-200mm f/2.8 lens weighs 2.85 pounds.) Tanks are cool and all, but I generally remind people they need an overhaul every 2,000 miles and get about 0.25 miles per gallon of fuel. I also remind people that I’ve never seen tanks used to deliver eggs – no matter how thick the armor plating is, delicate things inside are still delicate things. But definitely, this lens is built like a tank for whatever that’s worth.

The lens has a nice built-in sliding hood, which I’m always a fan of. The aperture ring moves easily and is “lightly clicked.” You can barely perceive the slight click with each stop. It’s not nearly as distinct as, for example, a Zeiss or Nikon manual aperture ring, but it’s certainly sufficient to tell by feel when you’ve changed the aperture. I kind of like it. The focusing ring is very smooth and turns with minimal resistance compared to most manual focus lenses, with clear hard stops at either end of the focus range. I kind of liked this ring, too. You will have to be careful where you place your hands on the lens when shooting, though, because an errant finger can easily move the focusing or aperture rings.

We hit our first snag at this point: one of the five lenses we received had a focus ring that popped past the infinity hard stop on the first turn. In looking at things a bit, it became apparent that the focusing ring has three tiny set screws which connect to the hard stops for the focus ring. We tightened them just a bit and all was well after that. (To some degree you can also tighten them a bit further to make the focus ring have a bit more resistance when turning.)

A Quick Geek Point

I end up knowing a lot of stuff about lenses I probably wish I didn’t. One of those things is that a lot of “specialty” lenses designed by one company and manufactured by another have absolutely no compensating or adjusting elements. The lens is assembled basically by stacking all the elements in place. If the company does any quality control, it consists of taking some shots after the lens is assembled. If it’s awful, it gets disassembled and the parts get put back in their bins with the hope they’ll match up better with other parts when they get put in another assembly. And yes, I know this first hand.

Because of inevitable manufacturing tolerances, this means some lenses are pretty good optically, some are absolutely crap optically, and buying one is like a box of chocolates – you never know what you’re going to get. And whatever you get is what you got. There are no optical adjustments that can be made.

This is what I thought we might see with the Ibelux 40mm. But we did open one up, not to do a complete teardown, but just to peek inside. What we found was most reassuring – there were shims to adjust tilt and centering associated with several of the elements. That not only means the optics can be adjusted. It also means someone was checking each element as it was placed, determining if it needed to be shimmed and how much. Which means my hopes for this lens as I headed to the test bench increased exponentially. This was a real optical device assembled with some care, not a bunch of glass elements stacked together on a hope and a prayer.

Optical Testing

Sensor Stack Tuning

My first question, since this is a very wide-aperture lens designed to work with m4/3, Sony E mount, Fuji X mount, and Canon M mount cameras, concerned sensor stack optimization. For those who don’t know, the m4/3 cameras have a very thick (4mm) sensor stack while the others are all around 2mm (you can read about it HERE if you’re interested). This “glass in the path” can affect wide aperture lenses, and this is certainly a wide aperture lens. Ideally, there would be a small adjustment made to optimize the 4/3 mount lenses for the thicker stack, while the others should all be roughly the same.

We tested both m4/3 and Sony mount lenses with 0, 2, and 4mm of optical glass in the pathway. We found that for both mounts, the lens performed best with 2mm of optical glass, worst with 0, and in between with 4mm. This probably means that people using the lens on m4/3 camera may not get quite as good performance as those using it on other mounts. (Blackmagic video cameras would be an exception, since they use a 2mm filter stack.)

The effect of sensor stack thickness on a micro 4/3 mount copy of the Ibelux 40mm f/0.85. You don’t need to know anything about reading MTF charts other than higher is better. The lens performs best wide-open with a 2mm stack.

Optical Bench Testing

We were able to test four copies of the Ibelux 40mm f/0.85 on our optical bench using the four rotation testing method and comparison algorithms we’ve used previously, and some new things we’ve been working on for a new company.

Intralens Variance

One of those tests is Intralens Variance. Basically, that means we test the lens in four different rotations, and graph the standard deviation of the four readings for each location and frequency. The best lenses have some variation. A tilted or decentered lens will have a huge variance. After we’ve tested a number of copies of each type, it gives us a good tool to compare how “even” the lenses are from side-to-side, corner-to-corner, and everywhere else.

Given my concerns about optical assembly and adjustment, I decided to use that test here, even though it is planned for other purposes. Since we’ve not used this before, I’ll give you a couple of examples from our database along with the results of this lens. The graphs below show the Canon 50mm f/1.2 (an average lens for this type of variance), the Rokinon 35mm f/1.4 (which has a fairly high amount of intralens variance), and the Ibulex 40mm.

This is a better performance for the Ibelux than you might realize. Wider aperture lenses generally have more variance than smaller aperture lenses, so this f/0.85 lens is at a disadvantage. Even so, it has more of a normal amount of variation than I ever expected. I thought it would be off the scale like the Rokinon.

Interlens Variance

One other thing we check is how much each copy differs from all the other copies of that lens. We do this several ways, but the simplest is a graph that represents how different you might expect the best and worst of five random copies to be. This graph actually measures in MTF along the left axis. Again, we’ll use the Canon 50mm f/1.2 for comparison, since it’s about average for all the prime lenses we’ve tested.

Again, copy-to-copy variance is greater for lenses of greater aperture, so the Ibelux again exceeded my expectations. It has a little more variation between copies than the Canon, but less than I would have expected given its greater aperture.

MTF Testing

I know, I know, you wanted to see it compared to the Leica Noctilux or the Voigltander 42.5mm f/0.95 or some dozen other lenses. Well, you’re going to get the Canon 50mm f/1.2 for comparison and like it. Because I don’t have anything but full-frame SLR lenses done using these methods, and I don’t have time to do another multi-lens test run today. Even old guys like me have stuff to do.

If you don’t speak MTF, just remember the basics: 1) higher is better; 2) lower frequencies (10 and 20 lp/mm) are about good, sharp contrast while higher frequencies are about fine detail resolution; 3) dotted lines and solid lines of the same color close together mean low astigmatism, far apart is high astigmatism.

Canon 50mm f/1.2 at f/1.2 compared to Ibelux 40mm f/0.85 at f/0.85. Note the Canon covers full-frame (20mm from center) while the Ibulex is tested to 15mm.

Canon 50mm f/1.2 at f/1.2 compared to Ibelux 40mm f/0.85 at f/1.4. Note the Canon covers full-frame (20mm from center) while the Ibelux is tested to 15mm.

Let’s face it, everyone. Right in the center, even at f/0.85, the Ibelux 40mm is as good as, or a bit better than, the Canon 50mm f/1.2. Stopped down to f/1.4 (there’s no f/1.2 click on the Ibelux) it’s clearly better in the center. Away from center, the Canon is clearly better. This is an amazing optical performance, though, and for an f/0.85 lens, simply amazing. In my expectations at the beginning of this article, I never expected this lens to do this well in the center. I didn’t even consider it a possibility.

So maybe now I know why they charge what they charge for it. This is a unique bit of glass. Okay, it’s not a “bit,” it’s a huge chunk of glass. My negative expectations have been completely discounted by a little objective testing. It’s built better than I expected. It has far less variation than I expected. And optically, given the aperture, it’s quite good. My hat is off to the designers at IB/E Optics and the manufacturers at Shanghai Transvision. Very nicely played, gentleman. Very nicely played, indeed.

I can’t tell you that it’s worth $2,000 to you, but I can certainly say it’s not overpriced for what it offers. This is an excellent lens.

Yeah, I hear you. You want some damn pictures.

You know better than that. You don’t get pictures in my geeky blog posts. But Darryl saw the optical results on the MTF bench while I was testing. I heard him disappear, but I didn’t realize he’d taken a copy of the lens with him.

So hear you go, some actual fine-art portrait photography by Darryl Bolin. Darryl is a repair tech, not a photographer. But you’ll figure that out once you see the images. However, they do show the center sharpness nicely, as well as give an idea of the bokeh, such as it is. All these are shot at f/0.85 under horrid industrial-quality fluorescent lighting.

BTW – Darryl says large metallic or inkjet prints are available for purchase, just contact him. Oh, and if you’re on a small screen, these spill off the right side a bit. Sorry about that but if I make them any smaller they just don’t show any background, which is the main point.

Pick your background carefully and the subject just jumps out.

Someone didn’t get sufficient coffee this morning. But you can see the bokeh can get a bit busy looking over Taylor’s left shoulder.

Darryl skillfully demonstrates that focusing at f/0.85 is a bit hit or miss. Unless he was focusing on the T-shirt’s right shoulder sleeve. Or perhaps he was demonstrating how focusing just a few inches from the face smooths the complexion.

This is right at minimum focusing distance, about 3 feet, and the depth of field is about the width of an 1.5mm screw, although this resize to 25% kind of hides that fact. It doesn’t hide the bokeh. Basically you’d probably want to avoid lots of small busy things in the background. Oops, this photo credit to Aaron Closz – I should have known who’d be taking the picture of the disassembled lens.

Roger Cicala, Aaron Closz, and introducing Darryl Bolin.

Lensrentals.com

August, 2014