Leica M240 vs SL2-S
As most photographers will attest, it's not the camera, but rather the lens that determines the picture. In terms of the basic image, that's largely true, but depending on the conditions under which you are shooting, one camera may have improved capabilities over the other. On this page I compare the characteristics of my digital rangefinder camera (M Typ 240) to my mirrorless SL2-S camera, though strictly speaking, both are mirrorless. In all cases, I use the same lenses, which have been designed for Leica's family of rangefinder cameras, both film and digital. These lenses possess an ideal combination of outstanding image quality, beautiful color rendering with high contrast and saturation, often conveying a 3-dimensional quality, while maintaining the smallest overall size.
Overall Image Quality
The M240 was introduced in 2012 with deliveries in the USA beginning is 2013 where as the SL2-S became available in early 2021. Both cameras have 24 MP sensors (ca 6000 x 4000 pixels) but are of different generations and origins. The SL2-S is based on the newer backside illuminated sensor technology with increased effective active pixel area and other readout improvements and has 1 to 2 stops of improved low-light / low-noise performance. Under most shooting conditions both camera deliver excellent images. I am also quite pleased working with 24MP images. I believe images from 24 MP full frame sensor provide an optimal balance for low-light/low-noise performance, image resolution/definition and storage size and processing speed. They have all the resolution I need to make large prints. I typically print 13" x 19" prints, but also 16" x 24" and am sure that 24" x 36" prints would be excellent. Image quality is generally not a determining factor in the selection of the camera body that I choose, with these exceptions.
Both camera have the tendency to produce skin tones which are at times too red. I have created a custom provide that shifts the red hue towards orange and reduces the red and orange saturation. Using Adobe Camera Raw, I created a profile which I often use to improve skin tone. Alternately, these same edits can be made directly in under the HSL/Color tab.
When shooting indoors under reduced lighting conditions it is not uncommon for the M240 to incorrectly set the auto white balance, rendering the image too warm. This can, however, be easily corrected in post. This has been corrected on later Leica rangefinder cameras.
When shooting night scenes, the SL2-S has significantly better performance at higher ISO settings - usable up to ISO 25,000. I generally limit the M240 to ISO 3,200, which has been improved on the M10 and again on the M11, and now equivalent to the SL2-S. In all cases, noise reduction and color recovery has taken a large step forward with Lightroom's AI based noise reduction capabilities giving impressive image quality at the practical limits of ISO operation for each camera
The SL2-S has higher overall dynamic range. The lower dynamic range on the M240 can result in noticeable color casts when trying to lift dark under-exposed shadows.
Everyday and Travel Photography
When it comes to having a camera that is either over your shoulder or in your hands taking a shot - then the my choice goes to the M240. Together with the accessory handgrip, which significantly improves your grip on the camera, the M240 is smaller and lighter than that SL2-S. This is only one factor. Equally important is the speed and pleasure of shooting with a rangefinder camera.
The M240 rangefinder viewfinder is optical and open, giving the most natural way to view the subjects and scenes in front of you. Focusing is achieved by aligning the superimposed images in the center focusing area. You never loose contact or context with your subjects. This is in contrast to focusing with an electronic viewfinder as is the case with the SL2-S or other mirrorless camera. To get critical focus using the EVF and wide-open apertures, one has to zoom in on the subject. With unsurpassed support for manual focus lenses, Leica makes zooming in and out nearly instant and effortless, but the very act of changing view is not nearly as natural, nor with experience as quick as is focusing with a rangefinder.
When shooting with a 50mm or longer focal length I often make use of the 1.4 viewfinder magnifier. This magnifies 50mm frame lines to fill the full field of view - taking the nominal 0.68 magnification very close to 1. The magnifier assists in critical focusing, but it also makes "two-eye" viewing very easy, with the left eye open on the scene and the right eye viewing through viewfinder - both with essentially unity magnification. That said, when I need to adjust focus, then I do close my left eye so that my right eye can focus on the double image focus patch.
One limitation of rangefinder focusing comes in to play when trying to shoot under poor lighting conditions. When a subject is poorly lit, then it becomes increasingly difficult to determine if the duplicate images are overlapping. With an EVF, the image is automatically exposure corrected and easier to see and focus.
One downside of using a rangefinder is the need to have a good calibration of the lens and camera to ensure accurate focusing. Each M lens has a cam ring on the camera mounting side of the lens that couples to the camera body and rangefinder's overlaying double image focusing mechanism. For longer focal lengths and when shooting with more open apertures, the calibration that assures good agreement is critical. I believe it's fair to say that calibrations hold quite well unless lenses are severely handled. Of my several lenses I've had to send my 50mm Noctilux off for calibration, owing to it's extreme maximum aperture of f/0.95. I've also had my older 28mm Summicron calibrated which could be due a to significant drop and bounce off concrete. Calibrating the camera can be done by most proficient users (1). What's critical is that lenses are in good, common calibration so that the camera calibration is not "chasing" individual lens miss-calibrations. Lens calibration can only be performed by Leica, or by one of a two Leica supported independent service operations in the USA and others worldwide (2).
Portraits and Weddings
When I'm doing work for a client and need the highest level of confidence that I'm achieving perfect focus on a subject's eyes and at full open aperture the depth of field can be extremely narrow, even less that 1 inch if the subject is close. In such case, the extra time and certainty that can be achieved by zooming in using the EVF is the better choice.
The second reason that I shoot with an EVF is to more closely set and evaluate exposure, both for ambient light as well as for the level of flash that I add. With on-camera flash, I generally use TTL, but do need to check the exposure and flash compensation. When using off-camera flash, I set the exposure and flash power manually. The ability to check and adjust these levels is best done through the EVF. It's really a must.
On the SL2-S the EVF is integrated. On the M240, the EVF can be optionally mounted in the camera hot-shoe. It should be mentioned, that real time viewing is also possible on the rear display of either camera, but in truth, when shooting outdoors, it is difficult to get a good view of a shot, particularly on the M240 which has an earlier, lower brightness and lower contrast display.
Though both cameras can operate with EVF, the M240 does have some limitations.
The SL2-S and newer rangefinder models offer higher EVF resolution. The M240 is rated at 1.4M dots and the SL2-S is specified at 5.76M dots. This difference is definitely noticeable. It's can be difficult to be sure that you have perfect focus when using the EVF to review pictures on the M240.
When zooming in for close focus, the lack of image stabilization makes using an EVF for longer focal length on the M240 can be a challenge. To solve this problem Leica introduced stabilization for the image viewed in the EVF on the M11.
Focus Peaking, which highlights the high contrast points in the image as they come into focus, is very helpful when focusing manually. The SL2-S (and I'm guessing newer Leica rangefinder cameras) offer both low and high sensitivity modes. Higher sensitivity presents more pronounce focus peaking highlighting - which is easier to see, but at the same time less critical to the precision in the actual focusing. My guess is that the M240 focus peaking corresponds more closely to the low sensitivity level. In either case, when the EVF zooms in for critical focusing, the sensitivity level drops (this is true for both the SL2-S and M240). This has the advantage of supporting a more precise focus, but if the lens does not deliver sufficient resolution and contrast (more challenging with the aperture wide open - and also more important) then focus peaking may cease to function. In my hands, I'm able to use Focus Peaking on the M240 with EVF when using the first magnification level, but focusing peaking highlights all but disappear at higher magnification when shot at f/0.95. For lower performance fast lenses from other manufactures, this may present a problem.
When the EVF is installed on a the M240 or any other Leica digital rangefinder camera, the hot-shoe, the sole point of contact for a flash, is no longer available. This means flash and EVF based shooting are mutually exclusive.
Flash control - The SL2-S and M240 support, Auto, Manual, TTL and HSS modes for most Leica flashes. While the M240 does support TTL mode with Leica flashes, its ability to handle large variations in exposure between subject and background for flash fill shooting is not at the same level as the SL2-S. In addition, I've observed that the M240 makes use of 2 pre-flashes (as opposed to 1 which is common practice) when shooting in TTL mode. This extra pre-flash and the increase delay to the actual picture flash means that some individuals will actually have their eyes partially closed when the picture is actually taked. The solution to this problem is to work in Auto mode which does not make use of pre-flashes. In addition, the SL2-S supports Godox XPRO II Leica and Profoto-Leica transmitters in Manual, TTL and HSS modes. The M240 can also make use of the Godox XPRO II Leica transmitter in Manual mode when the transmitter is placed in legacy hot-shoe mode.
Video
Among Leica rangefinders, the M240 is the only model that supports video recording. That said, the results are limited due to the lack of stabilization. When I have used the M240 to record video (not something I do very often) then I find it necessary to apply image stabilization in the video editing software.
The SL2-S is well regarded when used for video recording with many reviews available on the web.
(1) https://www.youtube.com/watch?v=lE7Yh5BgJ0I
(2) https://www.dagcamera.com/contact.html and https://skyllaney.com/services/ in the USA and, https://johnnymartyr.wordpress.com/2023/01/08/the-2023-leica-repair-tech-list/ worldwide