The focus of the camera is crucial to quality imaging. Poor focus can negatively affect details, lowering the effectiveness of the camera.
Cameras With A Fixed Length
Surveillance systems are commonly equipped with cameras that have fixed focal lengths without the ability to adjust the focus. Lenses can be impossible to access in many cameras, whether they are locked within a housing that can’t be opened in the field, or they are enclosed by a shroud or an IR illuminator that can’t be removed.
There are many cameras with accessible lenses in which the lenses are effectively glued in place and cannot be refocused. As a result there are limited options for adjustments which tend to lead to the camera needing to be replaced instead. However, some exceptions are specialty cameras that can make fine focus adjustments such as multi imager cameras and fisheye cameras.
Manual Focus Versus Auto
Two typical options for varifocal cameras are manual or auto. Once considered a high-end, premium feature, today it is common to find autofocus in most varifocal cameras. In contrast, manual focus is generally exclusive to specialized camera models with large imagers using photography lenses or repositionable multi imagers that have a limited amount of space. Although more of these models are switching to autofocus making manual focus increasingly insignificant.
Fine Focus And Zooming
Fine focus can often self-adjust focus by itself without affecting zoom. This is typically labeled as “Near to Far” or “Zero through Infinity”. Zooming adjusts the angle of view, which indirectly affects focus. This is typically labeled as “Wide (W) through Telephoto (T)”. You can find these controls on the lens of manual focus cameras or in the web interface of motorized lens models.
Ways To Focus Effectively
The first rule of thumb when adjusting any type of lens is to zoom before you adjust the focus. If you focus before you zoom it will always result in an unfocused image. There are two main features that affect this:
- Autofocus on motorized zooms: Many motorized zooms have automatic focus that follows zoom changes and autofocus is triggered as soon as the lens stops moving. As a result, users do not need to manually initiate autofocus.
- Focus to determine zoom level: In some cases adjusting zoom can result in extremely blurry images, which makes it difficult to determine zoom level. While zooming the camera to its desired field of view, it may be necessary to focus and refocus at least roughly.
Potential Issues While Using Auto Focus
Autofocus can be a useful feature and speed up the installation of your camera, but problems can still occur. These are the main three issues:
- The fine focus is incorrect.
- The focus fails when environments switch from day to night.
- The target is out of focus range.
If you are looking to review security features in your business, like Lens Focus let RC Security help. Our continued research and partnerships with premium brands allow us to offer better quality every time.
About RC Security Consulting
RC Security Consulting protects the heart of Texas with design, installation, retrofit, repair, inspection, and monitoring of commercial security systems. We are centrally located in Collin County and provide service for almost 200 miles in all directions.
