HTC One mini 2 Review

Focus & Capture Latency

Although image quality is a (big) part of the camera experience, camera UI and capture latency in particular are quite important. Long focus and capture latencies can really ruin the overall experience, not just from a responsiveness standpoint but also by contributing to missing a shot. At the very high end, devices like the One (M8) and Galaxy S 5 rely on external companion chips to improve focus times. In the transition to a lower price point, the One mini 2 loses any external imaging aids.

Though the camera UI looks similar to the M8's, it's very obvious that both focus and capture latency are substantially longer on the One mini 2. To quantify the difference I turned to the set of tests we introduced in the Galaxy S 5 review.

First let's look at focus time. I measured from the moment I tapped the focus target to the time the image stopped moving (I didn't rely on the AF lock indicator as some devices report focus lock prematurely). There's a bit more variance than I'd normally like in these numbers due to the nature of the capture, although I'm working on getting a higher speed camera to smooth some of that out.

The lowest focus latency I saw on the mini 2 was 850ms, but on average I saw around 1.2 seconds from tap until focus lock. That's about the speed of an iPhone 5c, but substantially slower than other similarly priced devices like the G2.

Focusing is just one piece of the puzzle, I also measured capture latency as well. I had to modify my criteria for measuring latency here a bit. Previously I just looked at the time between when I tapped the capture button on the screen and when the camera UI was ready to take another shot. For all other devices, that metric worked out fine - the mini 2 behaves a bit differently. The UI is responsive after about 250ms. In fact, on the mini 2 you can queue up to three captures in a row. The problem is the image captured won't be committed to NAND (and thus unavailable for review) until around 1100ms after you hit the capture button. The UI is still responsive during that time, but you haven't really completed a capture. What I'm looking at in the graph below is the time between capture tap and the image being stored.

The One mini 2 takes a bit over a second to complete a capture, which definitely hampers the experience. HTC does a good job of keeping the UI feeling responsive though. If you don't mind the image actually not being committed to NAND, the mini 2 provides the appearance of a 250ms capture latency.

This next chart combines the previous two values to give an overall picture of capture latency on these devices:

The One mini 2 ends up being our slowest device here. Even if you use the lower value for capture time, the mini 2 ends up around the middle of the pack. I suspect the Snapdragon 400's ISP definitely hampers performance here.

Still Image Summary

The One mini 2 definitely has the ability to deliver more detailed photos than the One (M8) in well lit scenes. For landscape shots or photos where a detailed subject is far away, the One mini 2 maintains an advantage over the M8. With subjects up close however, the advantage is far less pronounced and in many cases goes back to the M8:

Any advantage in spatial resolution the mini 2 maintains however comes at the expense of low light performance, which is more or less nonexistant on the mini.

In shooting with the mini 2 I definitely noticed more issues with blurring at the corners and a lack of uniformity overall, which is usually what we get with lower cost camera modules. Even my M8 sample shows more distortion on one side of the module than on the other.

Compared to other similarly priced devices, the One mini 2 generally falls behind in still imaging performance. You can find LG's G2 for around $400 now, which not only produces better photos in well light scenes but much better photos in low light as well.

Capture latency is also worse on the mini 2 compared to the M8. Focus and capture times are longer than previous generation flagships like LG's G2 as well. Despite the long capture time however, HTC does a good job of making the camera UI still feel responsive.

Video

The One mini 2 can capture high profile H.264 at 1080p30 with an average bitrate just south of 20Mbps. The device can also capture captures H.264 (baseline profile) video at 720p30 with an average bitrate of 11.8Mbps.

Video quality isn't particularly great, but it's usable so long as there's sufficient light.