Hikvision has focused on improving low-light performance for PTZs, an area that has traditionally been a problem, even more so than fixed cameras, due to the challenges of higher F stops and long-range varifocal lenses of PTZs.
Two of Hikvision's most notable efforts are (1) their Darkfighter PTZ line and (2) more recently, their DarkfighterX, the "next level of surveillance", that unlike any major manufacturer, uses 2 sensors, as Hikvision explains the "IR sensor delivers image brightness, the other sensor for visible light guarantees vivid color."
Very well written, very detailed report! I am wondering a few things though;
IR "Cut Off" When Zoomed Out
Is it possible that these types of IR issues could be fixed in firmware? Or is it a by design feature that is just an Achilles heel? It does seem to be a legit issue to me. You would think you would still need that distant area illuminated.
During testing, the DarkfighterX camera experienced moderate focus issues similar to other IR PTZs tested. In the example below, the camera fails to focus during the entire clip ~15 seconds.
By contrast, the non-X Darkfighter PTZ focused on the subject in only 2-3 seconds during a similar tracking example:
I couldn't help but notice that in these examples that the DFX model was zoomed in tighter on the subject walking. Do you find, in general, that PTZ cameras have more trouble focusing on subjects when using more zoom? Is there something inherent in the lens that causes this? Or is this simply a design issue with this DFX model?
Could this also be related to color vs B&W mode? Would the standard DF unit have these issues in color mode? Would the DFX model focus better in B&W mode?
I would think they could even out the IR illumination in firmware, yes. It seemed quite odd to me that it was such a sharp drop in illumination. Using the longer range LEDs at low power would likely improve it.
In the testing I've done, it's generally been easier to focus when zoomed further in. And actually that clip from the Darkfighter was taken at that zoom level/range because that was the longest it took to autofocus while tracking subjects in our tests (~3 seconds). In other cases it took even less time.
Good question on color mode. I would expect the non-X camera to autofocus worse in color mode, but simply because the image is darker and lower contrast since it turns IR off. The DFX keeps IR on, so the monochrome image isn't really any brighter/or better contrast.
So I wonder if the lens in the DFX unit is affected by the need to deliver images to two sensors? Wouldn't that be a different lens than DF unit? Maybe concessions had to be made in order to support the dual sensors and that leads to poor focusing capabilities? In that case, it is likely a product design issue and not something that could be improved in firmware?
what was the quantization level when you measured the bandwidth? When I did my research, 6MP camera generated around 1.2 mbps on medium with H.265+ enabled, and you tested 2MP with pretty much the same bandwidth consumption
Our bandwidth measurements were taken with the camera being used for tracking, as we mentioned in the text and included on the chart. So they're higher than average, since there's constant full screen change. When it's still, it's much lower, a few hundred Kb/s.