RESOLUTION

Resolution essentially means “How close can I zoom in to an image?”. The better the resolution, the more pixels are able to fit in an image. 

Well, all video is is many images shown very quickly within a certain amount time. This is actually defined as Frames per Second (FPS). Some government buildings and various schools may require FPS to be in “real time”, which is 30 frames per second or greater. Unless you are not required by law, the human eye can not notice separate images in footage until FPS is below 10-12 frames per second.

Back to the topic of resolution Many times, you will see a graphic that looks like this:

This gives the illusion that that the images get bigger as you have higher resolution. Well, that is only half true. This only means there are more pixels used to create the image. When you zoom in, you are effectively making an image the same size as something that is higher resolution.

For example, we have this beautiful image of a beach. 2190 x 1160 pixels, total 2,540,400 pixels

Now, let’s try to create this same size image with fewer pixels. Here, we have an image of 100 x 52 pixels, 5200 total pixels. This is 1/500th the resolution of the original

And just for fun, we have made an image of 6 x 3 pixels, 18 total pixels.

Of course, this is an exaggerated example just to get familiar with the concept.

Here’s another quick, more realistic example of the differences in resolution.Because you may not be viewing this page on a 4K screen, the difference between the 4K and 1080 image may be hard to see. Zoom into those images to see the difference.

So, how is this effectively applied to surveillance footage? The closer something is, the less resolution you need to get a clear image of the subject in view. In the first two beach pictures, let’s zoom in on an object that farther away and check out the difference: the stairs on the edge of the beach.

HIGH RESOLUTION

LOW RESOLUTION

You can barely tell what is going on in the the second image! It’s just too far away to understand. This is why it is important to understand what you hope to achieve with your camera system. Do you want to only see how crowded it is on the beach? Maybe see if there are any boats near the shore? Or is it more important to see individuals walking up the stairs? We also have video comparisons of what it means to have different resolutions at different distances:

The farther away a target is, the higher the resolution required to get a better picture. With that being said and what seems to have been a very strong argument to upgrade ALL your cameras to super high ultra definition, we at Sentinel Surveillance want to make one point very clear:

UNDERSTANDING RESOLUTION IS USED TO APPLY IT TO THE CIRCUMSTANCE OF YOUR SITUATION

We are not one size fits all!

Having a 4K camera in a room 15ft long is overkill, when a 1MP or 2MP camera is more than enough to see subjects with clarity.
If a client only needs to see if an employee is working behind the cash register, then 1080p is great! If the client needs to be able to see the numbers on the cash bills being exchanged, then having more resolution is recommended.

NIGHT VISION

A quick crash course on how traditional security camera night vision works:

Once the amount of light available is less than what the camera can detect, it turns on infrared light emitters which are invisible to the human eye but are detectable by the camera lens.
With this new “light source” the camera can now see in the dark! The only caveat is that IR wavelengths are just outside of the range that the human eye can detect, so it is perceived by us as black/white images.

A couple things to consider when comparing night vision
LUX rating
Range
Fill

LUX RATING [the least amount of light needed to function]

As a warning, this is a very simplified description of what it means and how it applies. There are other factors that affect nightvision like,
Once the available light dims to below this LUX threshold, the camera should kick into night vision mode and the IR illuminators will turn on.

Why do you want a good LUX rating? Well, the main reason is that you want to avoid seeing images in black and white.

You may be seeing new “color night vision” cameras (can also be called “Starlight” cameras), but this is a bit misleading. It only means the LUX rating is very low and can detect very low light normally. This doesn’t mean that the cameras will always work at night! They still have a threshold where it becomes difficult to see what is happening without enough light. It just happens that the threshold is super low but this may not be useful in all situations! If the the light is EXTREMELY low, then the “color night vision” is useless as you will just see pitch black anyway.

It is then necessary to have an IR night vision system available as backup! Black and white images are better than no image!

LUX Rating Chart
Full sunshine 10,000 LUX
Well- lit office 500 LUX
Comfortable reading 300 LUX
Cloudy 100 LUX
Twilight 10 LUX
Dusk 1 LUX
Full moon .1 LUX
Quarter moon .01 LUX
Complete darkness 0 LUX

LUX Sensor Camera Rating Chart
Traditional  >.1 LUX
Recent  <.1 LUX
Starlight  <.005 LUX
Color247  <.001 LUX

At Sentinel, we have cameras available down to .0005 LUX@F1.0!

RANGE [the distance at which the infrared can effectively view a target]

This concept is pretty is to understand, do you need to see a target at your front door, 10ft away, or cars parked on the street, 75ft away? It’s essential to be mindful of what the purpose of each camera is and how to cover your targets after the sun goes down.

Even if a camera has night vision, be mindful of how far the range extends.

Most web cameras, residential DIY, or doorbell cameras have a range of about 10ft-30ft.

Our own doorbell camera is no exception, as it is usually not needed to see farther than who is standing at your door.

The rest of our cameras are normally in the 100ft-130ft range, with the exception of some unique specialty cameras that can have longer ranges.

FILL [how the infrared acts within the viewing area]

Most pre-2014 night vision cameras have many IR LEDs surrounding the lens.

More recent technology, Matrix IR, spreads the IR light to fill the viewing frame completely.

Now these picture only show you a quick way to identify which IR system your cameras are using.

Here at Sentinel, we can repair older traditional cameras but we have completely switched all of our inventory to new Matrix IR systems.

What differences apply to the user?
Traditional IR usually sends light out like a flashlight. The brightest areas will be more in the center of the image and it becomes harder to make out what is happening on the peripheral edges.
Matrix IR spreads out the infrared more evenly across the image and allows brighter picture across the whole image!

A quick video comparing the types of fill within various spaces:

VIEWING ANGLE

The lens of each camera can either be more zoomed in or zoomed out. With variable focus lenses, you have more flexibility on what to focus on. When dealing with fixed lens cameras, knowing the focal length of the lens makes a huge difference! The rule of thumb: the lower the length, the wider the angle. For standard cameras, we usually use 2.8mm wide angle lenses.

 

Focal length / Viewing angle Chart
2.8mm ~108°
3.6mm ~ 78°
4mm ~ 70°
6mm ~ 42°
12mm ~ 22°

To see how this looks in real life, check out this video comparing 2.8mm/4mm/6mm viewing angles:

Unlike what you may have heard from an old school car commercial, wider is not ALWAYS better.
A concept to understand here is that when the field of view (FoV) is smaller, further objects are zoomed in to get a better quality image.

It becomes a balance between how detailed you want to see a target and how many targets can fit in your image.
Luckily, with a wider FoV you can increase the resolution of the camera to get the same quality of a camera that’s a bit more zoomed in.

Here at Sentinel, we believe you shouldn’t have to sacrifice and try to avoid doing so whenever we can. With that being said, it’s the reason this year we have switched our wide angle cameras to start at 5MP on all of our packages!

DURABILITY

How long do you plan on using your cameras? Regardless of what climate or weather throws at the cameras, they need to keep working.

IP “Ingress Protection” ratings are an easy way to compare the durability of any equipment, not just cameras!

Sentinel cameras are rated at IP66 or IP67, among the highest ratings equipment can receive, with only 2 standards higher the IP67. We feel that having a higher rating does not usually fit the needs of typical use and does not justify the higher cost (not only for us, but eventually for you!)

Though not necessary to have higher rating, you DEFINITELY should not have a lower rating than IP66 for your cameras! Water or dust can enter the critical “guts” of your camera and seriously damage the electronics.

Most common IP ratings you will see on cameras:
IP65 Enclosure – rated as “dust tight” and protected against water projected from a nozzle.
IP66 Enclosure – rated as “dust tight” and protected against heavy seas or powerful jets of water.
IP 67 Enclosure – rated as “dust tight” and protected against immersion.
IP 68 Enclosure – rated as “dust tight” and protected against complete, continuous submersion in water.

The best method we’ve found in determining a high quality system is to just look at the standard, out of the box warranty offered!

(Just a reminder, Sentinel offers a standard 3 YEAR WARRANTY on all new systems, equipment, and labor.