Ok.
Every network no matter how big or small it is must have a “nomination ip”, a broadcast address, and some ip addresses.
Normally you can have 254 different machines on one home network. That is how all routers and other home iot things are set up in default. That means that you can have ip addresses from say 192.168.1.1 - 192.168.1.254. This means that your network is a /24 network, your broadcast address is 192.168.1.255, and your “nomination ip” is 192.168.1.0.
But you can segment it to almost any portion. The portions are not obvious that is why you need a network calculator.
Lets stick at the default 192.168.1.0/24 network. A /25 network devides the /24 network in two halves, so you will have a network of 192.168.1.0/25 and one of 192.168.1.128/25. A /26 network devides your original /24 network into four subnets, so you will have 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, 192.168.1.192/26.
A /27 network gives you 8 subnets, and so on until /32, which is a special one ip network.
All you have to remember about this, is that the very first ip of the network is the “nomination ip”, and the very last one is the broadcast address. So you can not use those for any machine on the network. That is why you can not devide a network into 3 segments, only 2, 4, 8, etc.
So in the 192.168.1.64/26 network, you will have ip addresses from 192.168.1.65 - 192.168.1.126, which gives you 62 devices in one network.
According to your post /27 subnets would be enough for you, because a /27 subnet gives you 30 devices per subnet.
But you should keep in mind that after a couple of months you will forget about your subnetting and if you have more then 30 devices in one subnet then you will run out of ip addresses.
Because you actually have two different things you wish to separate (cameras, other devices) you can safely use /26 networks, which means you can have 62 cameras, 62 other devices, and still have 128 ip addresses to spare.
I have made a little drawing for you, for easier understanding.
The ip addresses on the my little diagram, are just examples. If your router has the 192.168.1.254 address, then you can give your computer 192.168.1.253 or anything else until you stay above 192.168.1.128.
Or if your network is built up from the “other way”, so your router has the address of 192.168.1.1, then you switch your other devices (raspberry pis) to the 192.168.1.128/26 network, and the addresses become: cam1: 192.168.1.129, cam2: 192.168.1.130, cam3: 192.168.1.131, cam4: 192.168.1.132 and cam5: 192.168.1.133. Everything else can stay the same as per my diagram.
Of course using subnets you will encouter your next problem, namely “howto give a device an appropriate address automatically?” But first you will need to get a little more comfortable with how a network works.
Hope this helps!
cheers
tom