The latest release of 645 PRO for iPhone adds a new feature specific to the recently-launched iPhone 5. It opens up access to iPhone 5′s low light support, which allows you to ramp up the “sensitivity” of the camera sensor by a factor of four.
With low light support, iPhone 5′s camera is able to increase its maximum ISO level from ISO 800 to ISO 3200. However, it doesn’t just do this by increasing the amplification applied to the sensor data—the method it uses between ISO 50 and ISO 800. Once you get past ISO 1000, the camera module gets down to a practice called “pixel binning”.
Pixel binning involves combining the contents of several adjacent pixels—a 2×2 matrix, here—into one. Clearly you then end up with a quarter of the original number of pixels so, in order to deliver a full-sized 8 MP image, the camera in iPhone 5 then upsamples (re-sizes) this smaller image by four times—which is why photographs taken using low-light support have substantially more digital noise than images shot at ISO levels below ISO 1000. In fact, they’re 2 MP images that have been enlarged to 8 MP!
So if you want maximum image quality at a technical level, stick to lower ISO settings.
But what if there’s not enough light for your shot? Surely there’s no choice?
Using Night Mode on 645 PRO
On 645 PRO you have the option, if there’s not enough light, to engage Night Mode by tap-holding the WB-L button. This gives you much increased headroom on another side of the “exposure triangle” to ISO—shutter speed.
The exposure triangle is the relationship between a camera sensor’s sensitivity (ISO), the exposure time (shutter speed) and the size of the hole that lets in the light (aperture). With iPhone, the aperture is fixed (f/2.4 on iPhone 5), so that will never change. However, the other two do—as can be seen on 645 PRO’s LCD display.
Because iPhone has a straightforward auto-exposure—AE—system (that is, due to the fixed aperture, effectively aperture-priority AE) it’s easier to think in terms of an “exposure V”. And the iPhone exposure V works, essentially, like this*:
- The “point” of the V (where ISO and shutter speed meet) is—on iPhone 5—ISO 50 and 1/15 sec
- If there’s less light, the ISO increases to 800 and then, with low light support on iPhone 5, ISO 3200
- If there’s more light, the shutter gets faster (up to 1/1000 of a second and beyond)
645 PRO’s Night Mode allows the shutter speed to drop to as much as 1 second—that’s 15 times more light than standard! Of course, as with iPhone 5′s native low-light support, there’s a compromise. In this case, it’s the comparative difficulty of taking sharp pictures with a slow shutter, whether because of camera shake (which can be solved by using a tripod, although that’s not always convenient) or subjects that won’t stay still.
The great thing for iPhone 5 users shooting with 645 PRO is that they can choose which compromise they want—a noisier image with a faster shutter speed, or a cleaner shot with a slower shutter speed. Because 645 PRO now provides both Night Mode and support for iPhone 5′s extended ISO range.
And if it’s really, really dark they can combine the two to capture images that would otherwise be totally impossible to get!
* In practise, it’s a little more complicated, specifically in the area near the point of the V, where things can get a little wooly, and where you may see exposure settings such as ISO 100 at 1/20 sec.. It’s also worth noting that there are differences between devices and iOS releases—iPhone 4′s ISO range is 80-1000, while iPhone 4S’s is 64-800 with iOS 5.x and 50-800 with iOS 6. And so on…