Leica SL (Typ 601) Exposure

Saturation & Hue Accuracy
Flat colors but with good hue accuracy from in-camera JPEGs. Vibrant colors from DNG files converted with embedded camera profile.

Note: In-camera JPEG results here are with SL firmware v1.2. A quick check of the latest firmware as of this writing (v2.1) revealed slightly lower default saturation and slightly lower hue accuracy with manual white balance, so we decided against reshooting our entire lab suite with the latest firmware and instead opted to compare in-camera JPEGs to ACR converted DNG files using the embedded camera profile which produces much more pleasing saturation and tonality than either default in-camera JPEGs or the default Adobe Standard profile when converting DNG files.

Exposure and White Balance

Indoors, incandescent lighting
Warm results with Auto and Incandescent white balance, a little cool with Manual white balance. About average exposure compensation required.

Indoors, in typical incandescent lighting, color balance was quite warm and reddish with the Auto white balance setting, though we've seen worse. The Incandescent setting was a bit warmer with a stronger yellow tint. The Manual white balance setting produced fairly neutral color, just a bit on the warm side. The SL required +0.3 EV exposure compensation, which is about average for this shot. (Note: Firmware v2.1 performed a bit better than v1.2 with Auto white balance under tungsten lighting, so these shots were taken with v2.1 firmware.) Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.

Outdoors, daylight
Muted colors, but with good exposure accuracy. Poor rendering of bright or dim skin tones.

The Leica SL handled tough outdoor lighting under harsh sunlight fairly well in terms exposure, but as mentioned previously, it struggled with skin tones in in-camera JPEGs. The SL underexposed our standard "Sunlit" Portrait shot as do most cameras, requiring +0.7 EV to keep the mannequin's face reasonably bright. (Most cameras need about +0.7 EV for this shot, so the Leica is about average here.) Skin tones were more pinkish and healthy-looking with Manual White Balance compared to Auto, but as you can see by viewing the full-resolution image, brighter tones such as on the mannequin's nose were harshly clipped with poor detail, while darker skin tones were desaturated and a bit grayish. (An ACR raw conversion produced much better results.) The Far-field image on the right has muted colors and it was just slightly underexposed with only a few clipped highlights in specular highlights where you'd expect. The shadows are extremely dark and somewhat discolored, but actually have good detail and low noise.

See full set of test images with explanations
See thumbnails of all test and gallery images

Resolution
~2,850 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns up to about 2,850 lines per picture height in the horizontal direction in JPEGs, and to about 2,850 lines per picture height in the vertical direction. Complete extinction of the pattern didn't occur before the 4,000 line limit of our chart. We weren't able to extract higher numbers with RAW files processed through Adobe Camera Raw, though the ACR conversion produced much higher levels of color moiré and false colors. Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Excellent sharpness and detail with very few sharpening artifacts. Some minor noise suppression artifacts at base ISO.

Sharpness. The Leica SL produced very sharp and detailed JPEG images at default settings, with almost no visible sharpening haloes around high-contrast edges such as the bottle label above left. We can thank the sensor's lack of an optical low-pass filter as well as Leica's sharp lens for that. (And you can always adjust sharpening to your liking.) Edge enhancement creates the illusion of sharpness by enhancing color and tonal differences right at the edge of a rapid transition in color or tone.

Detail. The in-camera JPEG crop above right shows some minor detail loss due to chroma noise suppression, as the darker areas of the mannequin's hair shows good detail. Individual strands are still distinguishable even in the lighter shadows, though some begin to merge as shadows deepen, and in places where the tone and color of adjacent strands is very close. The hair is also virtually free from chroma noise, which is often not the case. Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.

Aliasing Artifacts. As mentioned, the Leica SL captures very sharp, detailed images thanks to sharp optics and the lack of an optical low-pass filter. But that means it's also susceptible to aliasing artifacts when used with a sharp lens as can be seen in the "jaggies" in the hair above right (which the SL's demosaicing algorithm appears to exaggerate somewhat on close inspection), and also the moiré patterns in red-leaf fabric below. The camera does do a pretty good job at suppressing false colors, though.

RAW vs In-Camera JPEGs
As noted above, the Leica SL does a great job at capturing lots of fine detail in its JPEGs, though color and contrast produce someone drab images. Let's see how a RAW conversion using our standard converter (Adobe Camera Raw) at base ISO does with the embedded camera profile:

In the table above, we compare an in-camera JPEG taken at base ISO using default noise reduction and sharpening (on the left) to the matching RAW file converted with Adobe Camera Raw 9.1 via DNG Converter 9.7 using the embedded camera profile default noise reduction and some light unsharp mask sharpening applied in Photoshop (100%, radius of 0.3 pixels, and a threshold of 0).

Here, we can see that the Adobe Camera Raw conversion combined with sharpening in Photoshop delivers finer detail than the camera JPEG especially in the red-leaf swatch, along with slightly higher noise levels with default noise reduction. However there is a huge difference in color and tonality, with ACR producing a much more pleasing image when the embedded camera profile is employed.

ISO & Noise Performance
Very good high ISO performance for a full-frame camera.

Here we compare in-camera JPEGs with Adobe Camera Raw conversions using default noise reduction and the embedded camera profile across the ISO range (click crops for full images).

As you can see, noise versus detail performance is pretty good up to ISO 12,500 after which image quality begins to rapidly drop due to stronger noise and the effects of noise reduction. Both the in-camera JPEGs and ACR conversions show very low chroma components to noise which is often more objectionable than luma noise, though keep in mind the default noise reduction settings for ACR applies chroma noise reduction. Luma noise is fairly fine grained in JPEGs and very fine in ACR conversions, however the camera produces what look to be a lot of bright and even "hot" pixels above ISO 3200 which the JPEG engine effective suppress. There is also some horizontal banding (fixed pattern noise) visible at ISO 50,000.

Overall, very good noise performance for a 24-megapixel full-frame sensor, though some cameras with similarly spec'd sensors such as the Nikon D750 and Sony A7 II produce somewhat lower noise levels.

Of course, the impact of noise and detail loss are highly dependent on the size the photos are printed at, and pixel-peeping on-screen has surprisingly little relationship to how the images look when printed: See the Print Quality section below for recommended maximum print sizes at each ISO.

Extremes: Sunlit, dynamic range and low light tests
Poor handling of highlight clipping in JPEGs, though very good dynamic range in RAW files. Excellent low-light performance, capable of capturing bright images in very dark conditions.

Sunlight:
The Leica SL required +0.7 EV exposure compensation to keep the mannequin's face reasonably bright, but even then her eyes turned out a bit dim. As mentioned previously, brighter skin tones such as on the mannequin's nose are harshly clipped with poor detail, while darker skin tones are desaturated and grayish. Clipping in the white shirt and some of the flower also caused color tints as clipping occurred earlier in the green channel compared to the blue and red channels, which the SL's JPEG engine didn't handle well. Shadows were pretty clean however very deep shadows were posternized and clipped to black a little abruptly.

Above right you can see that Adobe Camera Raw produced much better skintones and more natural tonal transitions in the face, as well as no color tints in the white shirt. (Click on thumbnails for access to full-res images.)

Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here. In actual shooting conditions, be sure to use fill flash in situations like the one shown here; it's better to shoot in open shade whenever possible.)

Dynamic Range Analysis (RAW mode)
While we once performed our own dynamic range measurements based on in-camera JPEGs as well as converted RAW images (when the camera was supported by Adobe Camera Raw), we've switched to using DxO Labs' results from their DxOMark website. As technology advanced, the dynamic range of modern high-end cameras in some cases exceeded the range of the Stouffer T4110 density scale that we used for our own measurements. DxO's approach based on RAW data before demosaicing is also more revealing, because it measures the fundamental dynamic range of the sensor, irrespective of whatever processing is applied to JPEGs, or to RAW data by off-the-shelf conversion software.

In the following, we use DxO's "Print" dynamic range results, which are scaled based on camera resolution. As the name suggests, this scaling corresponds to the situation in which you print at a given size, regardless of how many megapixels the camera might have. (In other words, if you've decided to make a 13x19 inch print, that's the size you're printing, whether the camera's resolution is 16 or 300 megapixels.) For the technically-minded, you can find a discussion of the reasoning behind this here on the DxOMark website. Also note that DxO Labs uses a signal-to-noise (SNR) threshold of 1 when defining the lower boundary of acceptable luminance noise in their dynamic range measurements, which corresponds to the "Low Quality" threshold of the Imatest software we used to use for this measurement.

Here, we compare the Leica SL's dynamic range to the Nikon D750 and Sony A7 II, all 24-megapixel full-frame interchangeable cameras.

As you can see from the above graph (click for a larger image), the SL's dynamic range (in orange) at ISO 50 is almost as good as the Sony A7 II's (red) at ISO 100, at about 13.4 EV versus 13.6 EV, which is an insignificant difference. However at ISO 100, the Sony has about a 0.5 stop advantage. At higher ISOs, they are pretty similar, with the Leica actually besting the Sony slightly from ISO 1600 through 6400.

The Nikon D750 (in yellow) offers significantly better dynamic range of 14.5 EV at its base ISO of 100. However the Leica catches up between ISO 400 and 800 and actually bests the Nikon at higher ISOs, although the difference will likely not be discernible in real-world shots.

Bottom line: Very good dynamic range from the Leica SL, though not as good as some other full-frame sensors, at least at low ISOs. Click here to visit the DxOMark page for the Leica SL for more of their test results and additional comparisons.

Low Light. The Leica SL performed very well here, able to capture usable images down to the lowest 1/16 foot-candle light level we shoot these at (about 1/16 as bright as average city street lighting at night) at even the base ISO of 50.

Noise isn't an issue at ISO 50 and is very well-controlled at ISO 3200 with a fine grain to it and a very low chroma component. The top ISO of 50,00 on the other hand is rather noisy with strong luma noise and some noticeable horizontal banding (fixed pattern noise) as well. We didn't detect any issues with hot pixels in the camera JPEGs, however there are quite a few bright pixels in ISO 50,000 RAW files.

Color balance with Auto white balance is fairly neutral even at the highest ISO and lowest light level, just a touch cool.

LL AF: The camera's autofocus system was able to focus on both our high- and low-contrast AF targets down to below what we can accurately measure unassisted with an f/2.8 lens (about -8.0 EV), which is outstanding. It hunted slowly at lower light levels but eventually achieved proper focus and never gave false focus confirmation as some cameras do.

(Keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement. A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)

How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Mirrorless cameras like the Leica SL do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality

Excellent, high-resolution prints up to 30 x 40 inches at ISO 50-400; Nice 8 x 10 inch prints at ISO 12,500; and usable 4 x 6 inch prints at ISO 50,000.

Note: We normally print out-of-camera JPEGs but the Leica SL produced rather dull JPEGs, yet it produced very pleasing images from its .DNG files. So for this print quality analysis, we instead converted .DNG RAW files in Adobe Camera Raw using the camera's embedded profile with default noise reduction. This resulted in much nicer colors, better tonality and excellent overall image quality.

ISO 50 though 400 prints all look fantastic up to an impressive 30 x 40 inches, the maximum size we print these days. Despite having "just" a 24MP full-frame sensor, the Leica SL manages crisp, highly detailed prints up to this large wall-mountable size. Between ISO 50-400, images are extremely clean and free of noise, with ISO 400 displaying just the faintest hint of some finely-grained shadow noise -- nothing remotely strong enough to affect the print size.

ISO 800 prints almost join the earlier ISO levels at 30 x 40 inches, but we now see slightly stronger shadow noise. However, it's very, very well controlled and has an almost pleasing, film-like texture. To be on the safe side, we're calling the maximum print size here at 24 x 36, which looks excellent. For less critical applications or with additional processing, a 30 x 40 just might work.

ISO 1600 prints show another step up in visible noise, but it follows the same fine-grained appearance. Colors remain vibrant and prints show excellent detail up to a large 20 x 30 inches. 

ISO 3200 images make for excellent prints up to 13 x 19 inches. As expected, we see an increase in noise, but again it's very finely grained and not overly egregious. As such, we had a hard time again making the judgment call for print size here, but we erred on the side of caution. With careful post processing or for less critical applications, a 20 x 30 print could work here.

ISO 6400 prints top out at 11 x 14 inches, as the images are starting to show stronger noise that could be troublesome at larger sizes.

ISO 12,500 images display an impressive amount of detail despite the high sensitivity. The overall graininess of the noise is definitely noticeable but not a problem for printing up to an 8 X 10 -- or even an 11 x 14 for less critical uses.

ISO 25,000 prints are definitely on the noisy side, but the SL still manages a good print up to 5 x 7 inches. You might be able to get away with an 8 x 10 with additional noise reduction processing, which is quite an impressive feat given this ISO level!

ISO 50,000 images just pass the bar for a decent 4 x 6. There's still a fair amount of detail, but noise is quite strong and colors are now a bit on the drab side, preventing us from recommending anything larger.

Bravo to the Leica SL for the excellent performance on print quality! Again, we should note that we used converted DNG files rather than our usual "default JPEGs" since the image quality of JPEGs straight from the SL is disappointing and doesn't reflect what the camera can do. Up to ISO 400, the Leica SL is capable of some massive 30 x 40 inch prints. Even ISO 800 almost hit the 30 x 40 mark, but a slight increase in noise -- despite a rather pleasing, fine-grained appearance -- limited the size to 24 x 36 inches. As ISO rises further, noise gets subtly stronger and stronger, but for the most part maintains a nice, fine-grained appearance yet detail remains quite good. As such, we had a tough time calling the best print sizes at higher ISOs, as we imagine some careful post-processing techniques could offer a size or so increase in prints. We got a nice 8 x 10 all the way up at ISO 12,500 and managed a 4 x 6 at the maximum ISO of 50,000.

Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we routinely print sample images from the cameras we test on our Canon imagePROGRAF PRO-1000 printer. (See our Canon PRO-1000 review for details on that model.)