may be capable of recording slow motion video at 1000fps, similarly to the Xperia XZ Premium, the back of the box suggests that the feature will be branded as
But alright, ultra slow-mo video recording, we’ve already seen that. What makes the S9’s camera so special? Well, this would be the variable aperture. As noted on the box, the Samsung Galaxy S9’s main camera will be able to switch from f/1.5 down to f/2.4, depending on the scenario. This is actually very important for recording high frame rate videos, since the camera shutter needs to operate at an extremely high speed, which results in less light captured by the sensor. This makes shooting slow-mo videos in darker environments an exercise in frustration, especially when it comes to smartphone cameras. Of course, shooting in the standard for many smartphone cameras slow motion modes—which vary between 120fps and 240fps depending on resolution—is not nearly the same as shooting at 1000fps. This sort of frame rate necessitates a much, much higher shutter speed, which in turn requires a lot more light to actually capture a good video. This is why having the wider aperture is so important – it lets more light in.
Improved low-light photography, sharper daylight photos
Variable aperture on the Samsung W2018 flip phone
The wider f/1.5 aperture will not only come into play when recording Super Slow-mo videos, but also when shooting in low-light. When the environment is not well-lit, a camera with a fixed aperture is forced to rely on ISO and shutter speed controls to ensure proper exposure of the scene. However, with Samsung’s variable aperture, the Galaxy S9 will be able to switch between f/1.5 and f/2.4, depending on the scene, which should deliver better shots in low-light, but also sharper photos in well-lit environments, in theory at least. You see, the problem with wide apertures, despite all the perks, is that they could result in seemingly blurrier photos due to lens aberrations. Stopping down the aperture improves all-around sharpness throughout the frame, although a loss of detail can also occur when stopping down to extremely small apertures like f/16 or f/22. That’s called diffraction. But anyway, diffraction is not something you’ll have to worry about on the S9, unlike softness at f/1.5. Chinese outlets who got their hands on Samsung’s $3000 W2018 flip phone not that when shooting at f/1.5, the image is noticeably softer, which is normal. However, the phone can choose between apertures, depending on the light, and furthermore, even when when opening the aperture to its widest at night, image clarity could be improved on a software level.
Shallower depth of field (a.k.a better bokeh)
Photo taken on Minolta X-700, Helios 44-3 @ f/2.0, Rollei RPX 400
F-stop numbers on smartphone cameras don’t mean a whole lot when it comes to depth of field, unless you’re really close to the subject. Reproducing the shallow depth of field from the photo above, which I took with an old Russian Helios lens at f/2.0, is currently not possible on conventional smartphone cameras, at this distance from the subject and through optics alone. However, a wider aperture can still be beneficial in other situation.
Alright, so bokeh is a big deal right now. It’s been like that for a while in the photography community, but it’s now getting popular on smartphones as well, thanks to the recent boom of “portrait modes” and the like. Unfortunately, however, the shallow depth of field that can be achieved on a dedicated camera — be it on a crop sensor, full-frame, medium format, or the various sizes of film available — is an impossible feat for smartphones due to physical constraints. That’s why smartphone makers have resorted to software solutions to simulate an approximation of the shallow depth of field that can be achieved with a wide aperture lens on a large film plane.
Of course, smartphone cameras are still capable of producing a blurry background, when shooing from up close, but people are dreaming of artsy portraits where the subject stands out against a swirly backdrop of impressionist brush strokes. This isn’t possible on a smartphone right now—through hardware means, at least—and won’t be possible with the S9’s f/1.5 aperture, due to the sensor and other limitations. However, it will provide shallower depth of field when taking close-ups. Not to mention that Samsung could further accentuate the effect through software means.
Samples from the Samsung W2018 flip phone, which also has a variable aperture. Note the blurrier background in the shot taken at f/1.5
image source Sina
We don’t know anything about the sensor itself yet—pixel size and the like—but it could be the Dual Pixel ISOCELL Fast 2L9 12MP sensor that Samsung unveiled in October 2017. It’s a slimmer modeule, which would allow for fitting the variable aperture mechanism and the DRAM chip that’s in charge of image buffering when recording high frame rate videos, while keeping the camera flush with the phone. It’s interesting to note, however, that this sensor has smaller pixels than the ones Samsung used in the Galaxy S8/S8+ and Note 8 (1.28μm instead of 1.4μm). How Samsung intends to handle this change in pixel size, remains to be seen.