Sensor and Performance

The A530 is equipped with the PixArt PMW3325 sensor. According to specifications, the 3325 is capable of up to 5000 CPI, as well as a maximum tracking speed of 100 IPS, which equals 2.54 m/s. Out of the box, six pre-defined CPI steps are available: 500, 1200, 1500, 2000, 3000, and 4000 CPI.

CPI Accuracy

"CPI" (short for counts per inch) describes the number of counts registered by the mouse if it is moved exactly an inch. There are several factors (firmware, mounting height of the sensor not meeting specifications, mouse feet thickness, mousing surface, among others) which may contribute to nominal CPI not matching actual CPI. It is impossible to always achieve a perfect match, but ideally, nominal and actual CPI should differ as little as possible. In this test I'm determining whether this is the case or not. However, please keep in mind that said variance will still vary from unit to unit, so your mileage may vary.


I've restricted my testing to the four most common CPI steps, which are 400, 800, 1600, and 3200. As you can see, deviation is not entirely consistent, but pretty low overall, which is a good result.

Motion Delay

"Motion delay" encompasses all kinds of sensor lag. Any further sources of input delay will not be recorded in this test. The main thing I'll be looking for in this test is sensor smoothing, which describes an averaging of motion data across several capture frames in order to reduce jitter at higher CPI values, increasing motion delay along with it. The goal here is to have as little smoothing as possible. As there is no way to accurately measure motion delay absolutely, it can only be done by comparison with a control subject that has been determined to have the lowest possible motion delay. In this case the control subject is a G403, whose 3366 has no visible smoothing across the entire CPI range.


First, I'm looking at two xCount plots in order to determine whether there is any smoothing present, which would be indicated by any visible "kinks," and if there is, at which threshold it kicks in. As you can see, no such kinks can be observed at either 1600 CPI or 5000 CPI. The conclusion is that there is no visible smoothing across the entire CPI range. We can also see that SPI timing jitter levels are incredibly low, with very clean tracking to boot.


In order to verify the results from the xCount plots above, I'm looking at xSum plots generated at 1600, 3200, and 5000 CPI. The line further to the left denotes the sensor with less motion delay. I can measure a consistent motion delay of roughly 2 ms across the entire CPI range. It's not due to smoothing but something else. I do not know what could cause the delay.

Speed-Related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or SRAV for short). It's not about the mouse having a set amount of inherent positive or negative acceleration, but about the cursor not traveling the same distance if the mouse is moved the same physical distance at different speeds. The easiest way to test this is by comparison with a control subject that is known to have very low SRAV, which in this case is the G403. As you can see from the plot, no displacement between the two cursor paths can be observed, which confirms that SRAV is very low.

Perfect Control Speed

Perfect Control Speed (or PCS for short) is the maximum speed up to which the mouse and its sensor can be moved without the sensor malfunctioning in any way. Around 3.5 m/s you can see the sensor malfunctioning. Although 3.5 m/s is above spec (~2.5 m/s), it's still pretty poor for today's standards.

Polling Rate Stability

125 Hz and 250 Hz look nice. 500 Hz and 1000 Hz have some added variation that is still perfectly within acceptable boundaries.

Paint Test

This test is used to indicate any potential issues with angle snapping (non-native straightening of linear motion) and jitter, along with any sensor lens rattle. As you can see, no issues with angle snapping can be observed at any CPI step. As expected from a sensor with no visible smoothing, jitter linearly increases with every CPI step. It's still reasonable all the way up to 5000 CPI, though. Lastly, there is no sensor lens rattle.

Lift-off Distance

The A530 does not support adjusting LOD. The only available (default) setting is high as the sensor does track at a height of 2 DVDs, but not at a height of 3 DVDs. Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

Since mechanical switches are being used for the buttons in most computer mice, debouncing is required in order to avoid unintended double clicks. Debouncing typically adds a delay (along with any potential processing delay), which shall be referred to as click latency. As there is no way to measure said delay directly, it has to be done by comparing it to a control subject, which in this case is the Logitech G100s. Click latency has been measured to be roughly +13.2 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. Please keep in mind that the measured value is not the absolute click latency. Comparison data comes from this thread as well as my own testing, using qsxcv's program.