I would like to ask. Do you think it’s a good idea to build the network for the cameras with Mikrotik devices? We are planning to install around 50 PoE cameras. I don’t think any of them need more than 30W so 802.3at would be enough. We have also Mikrotik wireless p2p links so we will also use Passive PoE.
I am planning to use these devices:
CRS112-8P-4S-IN
CRS328-24P-4S+RM
hEX PoE
I would like to also know the PoE budget for these devices, because I couldn’t find it in brochure.
Can I mix 802.3at camera on one port and Passive Poe powered device on another?
Check what are your cameras power requirements, but unless you have some special cameras that requires higher power (PTZ for eg) you will be fine with Mikrotik devices. All of them supports 802.3 at/af and passive poe with autosensing.
But check hEX poe if that supports passive poe out, i can’t find that information.
I am using Hex Poe outdoor, with 120 Hikvision cameras, everything works fine, I am using 1gb sfp moduls and its connected to CRS326 with 24 SFP ports.
1 HEX poe / 4 x camera
1 HEX poe / 2 x Hikvision license plate reader camera
Setup works since 3 years, under this time only one HEX POE dead and one power supply. (+ 4 camera, but its totally okey under 3 years)
I wanted to use everywhere RB960PGS, because of the OS… So I recommend to use it, but before buying anything, make sure it can deliver enough power to the camera. (Included heating etc, for example if the camera turns into night mode, than it will eat more, thats why I can use 2 license plate reader only from a single hex… but its still okey for us. )
Normal cameras are usually in the 802.3af range, around 15 W.
A number of Mikrotik devices including the hex PoE have a limit on PoE compatibile voltages 48 V typical, max 56-57 V, of 450 mA per port which is near the border (if not below it) of the 802.3at standard.
Besides, Mikrotik devices like the hex use Mode B for the PoE.
Even if in theory 802.3af/at powered devices should be compatibile with both modes A and B, It has to be checked with attention as many devices only work in mode A.
See: http://forum.mikrotik.com/t/hex-poe-not-doing-poe/173021/1
So I recommend to use it, but before buying anything, make sure it can deliver enough power to the camera. (Included heating etc, for example if the camera turns into night mode, than it will eat more, thats why I can use 2 license plate reader only from a single hex… but its still okey for us. 
)