When we reviewed the Nokia Lumia 1020 we praised the outstanding overall camera performance, but noted there were some areas of weakness, notably around start-up time and shot-to-shot time. The relatively poor performance here was partly a consequence on the on-board Snapdragon S4 SoC not really being designed to support camera modules with sensor sizes above 20MP.
|SoC (processor)||Camera MP||Max. Camera MP (SoC)|
In order to get things to work on the Lumia 1020, Nokia was obliged to rewrite the entire imaging stack. The end result is undoubtedly an impressive technical achievement, but most consumers will, quite rightly, only ever care about real-world performance, not about how it is achieved. Therefore, some frustration with the Lumia 1020's camera speed is quite justified. The idea that the Lumia 1020 was released a little too early may be stretching things a little too far, given the multitude of factors that go into the timing of product development and release dates, but it is not an entirely unreasonable view.
Making a comparison between the Lumia 1020 and 1520 can help illustrate this point. From the get-go, we should be clear that this cannot be a direct comparison; the Lumia 1020, given the respective camera specifications, is pushing many more pixels through its imaging stack. That means any performance difference is a complicated result of both camera and processor specifications changes.
The video above shows that there's a small difference in camera start-up time, but probably not enough to be significant in most use cases. By contrast, the difference in shot-to-shot time is quite startling, with the Lumia 1520 getting close to capturing three photos in the time it takes the Lumia 1020 to capture one (i.e. a shot-to-time for the Lumia 1520 is one third of that for the Lumia 1020).
What this means, in practice, is that with the Lumia 1520 you are more likely to capture a "good" photo when taking a series of pictures in quick succession (i.e. fast moving objects or rapidly changing situations).
While it is tempting to ascribe the majority of the Lumia 1520's superior performance to the smaller megapixel count (after all, shouldn't half the megapixels mean half the shot-to-shot time), the reality is that photo processing is more complex than a directly proportional calculation would imply. Our view would be that it's the processor that's making the most significant difference here, something that can only make us look forward to seeing Nokia's next imaging flagship arrive with an up to date processor.
Another way of looking at this is that the Lumia 1520 has very similar camera performance characteristics to the Lumia 925. That's despite the significant extra overhead involved in processing more than double the number of pixels, carrying out the oversampling to 5MP, and writing two files to memory. This "good enough" camera speed, contrasted with "acceptable trade-off" on the Lumia 1020, is one of the reasons we anticipate the Lumia 1520's 20MP/5MP oversampling camera becoming standard in higher end Lumia devices next year.