What is ePTZ and how does ePTZ compare with true PTZ?
ePTZ uses the technology of digital zoom to provide true PTZ-like features on a fixed (non-PTZ) camera. Digital Zoom works by simply magnifying pixels. When you do this, you are essentially focusing only on a portion of the entire camera image at any given time and magnifying it to fill the entire frame. Since you are only viewing a portion of the image at any given time, you can now move that ‘area of interest’ across the entire camera image to affect a pan and tilt effect (without moving the camera head). So digital zoom not only allows you to ‘zoom’ in on an image but also to move around within that image when zoomed.
However, there are advantages and disadvantages to using digital zoom and ePTZ.
The main disadvantage is that you are magnifying pixels to accomplish digital zoom. This results in reduced resolution. For example, a 4K video camera digitally zoomed in at 3x, results in a final video resolution of only 720p (a loss of total resolution of 88.9%). This is a very significant reduction in resolution and image quality. Therefore, you need to consider your application and its needs before deciding whether ePTZ can work in your application or you should instead invest in a true PTZ camera. One simple example would be if your streaming output or final file resolution is only going to be 720p, then a 4K camera with ePTZ limited to 3x will be sufficient, as the higher resolution is not required in the final product.
There is another intrinsic disadvantage to ePTZ here as well. Looking at the 4K ePTZ camera example above (today’s practical limit for available, affordable cameras), a 3x zoom will take you down by 88.9% to 720p (as mentioned above). However, even if 720p is acceptable for your final product resolution, you are limited to only 3x zoom to remain at 720p of higher. With true PTZ technology, you can get cameras with an optical zoom range from 3x all the way up to 30x optical zoom, without reducing your final product resolution by a single pixel. Again, your specific application will dictate whether ePTZ will suffice.
Another disadvantage of ePTZ vs true PTZ is the range of view. A true PTZ camera can often pan by as much as 340 degrees horizontally and tilt bay as much as 120 degrees vertically. This allows a single camera to cover a huge area of the local environment or ‘set’. An ePTZ camera, on the other hand, is limited to the field of view of its fixed lens and fixed camera head. This can typically range from 40 degrees to 110 degrees horizontally, with a common field of view being around 70 degrees (vs 340). Therefore a much larger quantity of ePTZ cameras will be required to cover the same ‘set’. As with resolution, an evaluation of your specific needs will determine whether ePTZ or true PTZ is a suitable choice for your application.
Does ePTZ technology have any advantages?
It does have a few, so long as the above requirements are first met. An ePTZ camera has the ‘magical’ ability to move instantaneously to a new shot (via a called preset or a direct PTZ position command). This can be very useful for some applications. There is absolutely no wait for framing the new shot. With a true PTZ camera, you will have to wait for the mechanical motors to move to the new P, T and Z positions. However, the disadvantage of this is that with most (if not all) modern ePTZ cameras, you simply cannot produce a panning, tilting or zooming sequence without physically moving the camera through space. As ePTZ technology develops, we will likely see ePTZ panning tilting and zooming sequences become available to better emulate the capabilities of a true PTZ camera.
Some other advantages of ePTZ technology, if the above needs are first met, are size and cost. Without the need for mechanical pan, tilt and zoom mechanisms, the size and cost of ePTZ cameras can be significantly lower than true PTZ cameras. This size and cost offset is typically greater than the cost of the higher resolution imaging chip required for a ‘usable’ ePTZ experience (like 4k vs 1080p imaging chip), resulting in a lower overall camera cost. This cost reduction may in fact be enough to offset the additional cost of a second or 3rd ePTZ camera to potentially address the ePTZ range of view problem mentioned above.
Understanding all of the impacts of ePTZ vs true PTZ and the specific needs of your application will help you to make the right choice when deciding between ePTZ, true PTZ or a combination of both technologies for your production.
PTZ camera use is increasing each year, and shows such as NAB are highlighting new PTZ products and solutions. To learn more about the PTZOptics line of PTZ cameras and ePTZ cameras, reach out to one of our team members at [email protected]