Article Index

Resolution

It is hard to expect any miracles from older lens designs like Summitar. Keep in mind that the lens was designed in 30s, when the lens designers' philosophy was not centered about absolute resolution. Still, while Leica Summarit 50mm f/2 does not exhibit the highest absolute resolution, it does fair reasonably well, as can be observed from the simplified MTF50 charts below. As a reminder, the Imatest experiments were run in the 1m to 10m focusing range, with the absolute best results graphed into the chart you see below. You can observe that Summitar clocks a reasonable resolution in the center at f/2, which improves slowly with stopped down aperture, peaking somewhere around f/8. Border resolution is where the lens exhibits major weakness, with corners remaining significantly softer all the way through f/5.6. There is a measurable performance boost around f/8, bringing corner resolution to very decent levels according to the MTF50 results. Basically, the lens exhibits very similar to Summicron 50mm f/2 Rigid (also reviewed recently) resolution pattern, but lacking the Summicron around corners where the improvement gains with stopped down aperture is much slower.

 

Leica M8 (10Mp)

 

Looking at the crops from the test target, you can see the fairly significant difference in quality the lens produces with wide open aperture and stopped down to f/8. Corners at f/2 are outright soft, with not that much detail carried through. The overall quality also seems to suffer further because of the lower contrast, which we will discuss in the next section. On the other hand, results at f/8 are quite good - while not as clinically sharp as with some of the modern lenses, quality seems reasonable to a naked eye. But let's take a look at how the lens performs in field test.

 

Leica M8 (10Mp)

 

The series of crops below compare image quality that Summitar offers when focused at infinity. The distance to the target was greater then 20m. I took several series of focus bracketed shots around infinity and then selected the series that produced visually sharpest results. As you can see, the lens is fairly soft wide open - while center might barely pass the Ok threshold, borders are outright soft. But perception of sharpness actually suffers even more here because of the much lower contrast at f/2 (the crops below are straight out of camera with no post-processing applied). Furthermore, Summitar also exhibits mild degree of field curvature, which can also cause some confusion among users - at close to MFD distances and wide open apertures, you will actually see the corners of the images are slightly softer then they ought to be. A little play with the focusing can bring up slightly better corner results at the expense of the center quality. It's a trade-off, but it does not bother me personally. since it is a non-issue given my preference to shoot for shallow DOF at MFDs. Smaller apertures and longer focusing distances mask this problem fairly well.

 

Center

L.L.Corner

U.R.Corner

 

On the final note, here is a simplified chart that tries to capture the resolution dependency of the lens to the focusing distance used. The chart averages MTF50 resolution numbers from Imatest across all aperture positions and measurement points for given focusing distance. For example, a plot at 1m is calculated as an AVERAGE (MTF50 (Center,@1m,f/2), MTF50 (Borders,@1m,f/2), MTF50 (Center,@1m,f/4), MTF50 (Borders,@1m,f/4),...). While not really a scientific measurement, it tries to give you a glimpse into whether the lens performs better up close or at a distance.

 


Color & Rendering

If you are reading this review, you're probably interested in a 'non-mainstream' lens and have certain expectations for Summitar to meet that 'non-mainstream' label. Summitar is one of the very few old lenses I have kept around from my old film days specifically because of that - I don't really have a better explanation for why I have not yet parted with the Summitar. Jumping ahead, I would argue that this is not a lens for everyone - you will quickly discover that the quirks of this lens need getting used to and do not justify the small amount of money you're saving by choosing a second hand Summitar over a more modern lens like Zeiss Planar T* 50mm f/2 ZM. But since you've made a conscious decision to evaluate Summitar, all the capabilities of a modern lens probably pale in comparison to the look and feel you are trying to get from this lens. But let's do this in an orderly fashion...

ISO 320, 1/90, f/2, 50mm

In my recent review of Leica Summicron M 50mm f/2 Rigid, I claimed that Rigid has a fairly low contrast at wide apertures. Compared to the Rigid Summicron, Summitar has an even lower contrast, and not only at wide apertures, but pretty much throughout the entire aperture range. Contrast obviously varies slightly depending on the shooting conditions - lowest in strong direct light and slightly better in neutrally lit environments. Of course, better is a relative term here - Summitar is nowhere close in its contrast capabilities to lenses like Planar 50mm f/2 ZM or Biogon 35mm f/2 ZM.  Images straight out of camera actually do look fairly bleak, as if you applied a neutral grey mask to the entire frame, and need modest amount of post-processing work to make the image colors look richer. Unfortunately, this is not always possible - I had the worst luck trying to recover contrast in images taken with Summitar in daylight, where the lens continuously overexposed images by ~1EV. Dialing down exposure compensation obviously helps reduce probability of blowing out highlights, but at a cost of clipping off some detail in shadows. But if you do manage to capture your images without clipping off too much data, you will find Summitar files fairly easy to manipulate - my most favorite use of this lens is actually for indoor photography where the lens seems to produce more even luminocity distribution, which in turn gives me more flexibility in adjusting contrast and saturation without the need to deal with more complicated recovery methords .

Interestingly, you will notice that while Summitar produces overall low contrast, it does have a fairly decent tonal reproduction, particularly in mid-tones. I was surprised by that, but it kind of makes sense, since with the pretty constant overexposure and lower contrast, the lens shifts color gamut towards white, hence also shifting a good portion of shadows into mid-tone range.

One other interesting side effect of the low contrast is absence of lateral chromatic aberration. 'Absence' is probably too strong word here - Imatest does capture some levels of CA, but from practical perspective, unless you're eyeballing your images at 100% magnification, you would not notice any color fringing. The chart below summarizes Imatest results, which show that CA levels average ~0.35px in the center across all tested aperture levels, while border CA reached ~0.4px at f/2 and declines to ~0.25px by f/8. Summitar does show mild levels of spherical aberration though, particularly at wider apertures. Many users like this characteristic in portrait lenses since it often helps create smoother facial tones, sometimes even make portraits look celestial because of the spherical crown phasing out of the in-focuse areas.

 

Leica M8 (10Mp)

 

DOF & Bokeh

As I mentioned earlier, I find Summitar somewhat of a handful to deal with. This also comes to the look and feel of bokeh that the lens produces. While I tend not to label bokeh of any particular lens as 'good' or 'bad', I must admit that Summitar's bokeh capabilities are consistently unusual to say the least. This 'unusualness', in my opinion, comes from two characteristics of the lens - longitudinal aberration that the lens shows at wider apertures and the general low contrast it carries through all aperture settings. The longitudinal aberration often produces fairly sharp outlines in out of focus highlights, as if somebody took a sharp white pencil and outlined OOF highlights with it. This can be observed in a number of sample shots, which when combined with low overall contrast tends to be rather 'hard' on the eyes. On top of that, I have noticed that Summitar tends to produce somewhat ovalish highlights, which can add a little bit to the strange feel of bokeh.

ISO 640, 1/45, f/4, 50mm

If you search the web for Summitar reviews, you will find many references to the so called 'swirly' bokeh that this lens produces.This is an interesting characteristic of the lens that majority of users seem to agree on. Naturally, there is a difference in opinion what is 'swirly' and from my personal tests of this lens, I can't seem to put a finger on when the lens actually gives the so called 'swirl' to the OOF highlights. You can see a little bit of that in the shot displayed in the previous section, but not in the one on the right hand side. Without doing a little bit more testing, I am hesitant to make a definitive conclusion here, but it seems to me that the swirly happens more often brightly lit environment, with the OOF objects that are located at farther distances. The longitudinal aberration that the lens produces seems to exacerbate and adds to the feeling of 'business'. In darker environments, where the OOF background is noticeably darker then the foreground, this does not seem to be much of a problem. On  a personal note, I don't really find Summitar's bokeh in such cases particularly attractive and almost never keep the final image.

As is customary with this section, we're going to start with a shot of a ruler to simulate the shallowness of DOF at the minimum focusing distance. The shot was taken at ~45 degrees to the surface. Using online DOF calculator, I'm getting ~3.5cm, with the near limit at 98cm and far limit at 1.02cm. This is pretty much identical to Simmicron Rigid and like with the Rigid you see that the DOF area reasonably shallow, but the out of focus transitions are more gradual then with the lenses that offer combination of shorter MFD and faster max aperture. You can notice how flat the colors really are here - even with 2 500W lights bounced off the ceiling, lower contrast and overexposure pushed luminosity too much, clipping the details and bleaching out colors.

 

ISO 320, 1/90, f/2, 50mm

 

Like with the Rigid Summicron, Summitar's bokeh capabilities are affected by its minimum focusing distance more then by its aperture. The two sets below demonstrate what DOF will look like at MFD of 1m and stepped away to ~3m with wide open and stopped to f/8 apertures. At MFD distances, Summitar produces reasonably well-blurred background - it is not as smooth as with faster lenses like Voigtlander Nokton 50/1.1 though, and you can see enough detail around larger background objects. There is a hint of double edging in the background, but it is fairly mild and does not seem to add too much 'disturbance'.The feel for isolation disappears quite rapidly though, as you move away from the focused target - at 3m, Summitar produces background blur that carries much more detail for my taste - it has almost as much detail as a shot done at MFD but stopped down to f/8.

 

DOF @ 1m

'

ISO 160, 1/2000, f/2, 50mm

ISO 160, 1/250, f/8, 50mm

DOF @ 3m

ISO 160, 1/4000, f/2, 50mm

ISO 160, 1360, f/8, 50mm

 

Given the low contrast that the lens produces streight out of camera, the feel of 3Dimensionality is rather lacklaster. While I personally don't mind low constrast, washed out background in images, I do want to see higher contrast in the center, so that there is a fairly pronounced separation between the foreground and background. With Summitar, as I mentioned earlier, the feel is much more subtle, and you'd end up tweaking the images in postprocessing to bring additional detail that the lens hides.

 

ISO 320, 1/180, f/2, 50mm