I am developing an app that aims to capture video of fast-moving objects without motion blur, so I want to set the exposure time as low as possible.
In order to do this, I take advantage of the automatic exposure settings, then when I want to capture I have written some logic to reduce the exposure time to something short (e.g. 1 ms) and increase the ISO by a corresponding factor up to it's maximum.
I found that on my test devices (an iPhone 6 and an iPhone 8), the maximum available ISO at the 1080p format I want to capture is quite low, so I am stuck with longer exposure times if I don't want the resulting video to appear underexposed.
I found this summary of iPhone camera device capabilities:
https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Cameras/Cameras.html#//apple_ref/doc/uid/TP40013599-CH107-SW24
Taking the iPhone 8 as an example, I can see that all of the 1080p capture formats have an ISO range of 22-880 (Table 4-4), but the 1440 x 1080 formats have an ISO range of 22-1760.
Some other formats have a different range (e.g. 3264 x 2448 has a range of 22-2112).
I don't understand the connection between these different formats and the available ISO range. Are some formats just optimised for low light conditions? If so, why does it seem that the 1080p formats in particular have reduced ISO ranges?
In order to do this, I take advantage of the automatic exposure settings, then when I want to capture I have written some logic to reduce the exposure time to something short (e.g. 1 ms) and increase the ISO by a corresponding factor up to it's maximum.
I found that on my test devices (an iPhone 6 and an iPhone 8), the maximum available ISO at the 1080p format I want to capture is quite low, so I am stuck with longer exposure times if I don't want the resulting video to appear underexposed.
I found this summary of iPhone camera device capabilities:
https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Cameras/Cameras.html#//apple_ref/doc/uid/TP40013599-CH107-SW24
Taking the iPhone 8 as an example, I can see that all of the 1080p capture formats have an ISO range of 22-880 (Table 4-4), but the 1440 x 1080 formats have an ISO range of 22-1760.
Some other formats have a different range (e.g. 3264 x 2448 has a range of 22-2112).
I don't understand the connection between these different formats and the available ISO range. Are some formats just optimised for low light conditions? If so, why does it seem that the 1080p formats in particular have reduced ISO ranges?