How to Choose a Photo Strobe

There are a decent amount of options out there. Here are a few questions to ask yourself which will help with the selections.

How much power do you need?
Of course this is related to distance from subject and what modifiers you use. Here are a few form factors of lights. Basically the more powerful a light is, the larger it is as it needs space to hold the power.

• Speedlights. These are meant to plugged into the hot shoe of your camera but can also be used off camera. They typically use batteries. I recommend ones that use lithium batteries as they'll recycle faster and last longer vs AAs. Their power output is typically <100W.
• Monolights. They may battery powered or not. Their power ranges from about 100W-1000W.
• Packs. For most people using packs/heads will be in a studio or in a fixed location as routing wires is more annoying when you need to be mobile. The lower powered ones are typically wall powered but some are battery powered. There aren't many of these anymore as battery powered monolights have taken their place. The only advantage in a lower powered system is to save weight on the head. Power wise packs are typically from 600-2400W but historically I've seen packs start around 100W but they aren't that popular anymore. You have to be careful with lights that are strong e.g. 1200W and 2400W and wall powered because you may need dedicated power circuits for those of they may blow a fuse if fired too rapidly and if there's other power hungry things on the same circuit.

How fast are you going to shoot?
If you want to take shots rapidly, the strobes need to be able to keep up. Speedlights used tech called IGBT and eventually it was scaled up to the larger size of the other kinds of lights, monolights and packs. This allows the power to be topped off and power comes off the top as opposed to the power drained and filled up to the amount needed for the power setting. I'm only going to talk about flashes of the modern first type not the later type. Still each system has a speed at which they can recharge and fire. The more expensive flashes have more capacitors and/or more expensive batteries that can handle the speed. Having larger power capability leaves more in the bank.

e.g. A 200W strobe firing at full will recycle at it's slowest vs a similar light of 600W that will have 400W in the bank. 

How good of color consistency do you need?
Firing fast may lead to color shift. Different packs or bulbs of different ages may have different color temperatures. Using a flash in freeze mode (which is shorter flash duration to stop action) will lead to more inconsistency as well.

The more affordable brands are not that far off from more expensive brands now. It changes on a model to model basis. I'll leave a YouTube video comparision here with data they've taken. There isn't too much data on this out there.

What kind of modifiers do you want to use?
Some modifiers are generic but some are particular to a system. It maybe to possible to change speedrings or use adapter to use one system's modifier on another. There are plenty of brands who use Bowens mount and then others which are specific only to their brand e.g. Profoto. Sometimes even within Profoto they have different mount depending on the model e.g. OCF and Clic for Profoto. The reason for that is they have different sized product where smaller ones obviously can't natively use the bigger one's mount.

What level of portability do you want to have?
Large lights and modifiers need robust stands and it can get out of control really quick in terms of size and weight.

Do you need battery power?
These can come as dedicated internal batteries. Some wall powered units can use generators / inverters that use Lithium batteries nowadays. Their recycle time maybe slowed by this and you have to match the power accordingly. You don't want to use a power hungry flash with a weaker generator/inverter as it may blow it's fuse.

Are you going to use manual power only or need automatic exposure (TTL)?
For event shooters or where the lighting is uncontrolled and your subject is also moving around, this could be a useful feature to have. You're going to have to have a flash and/or trigger which supports it.

How about other features like High Speed Sync (HSS)?
This is only relevant using the flash outdoors and using focal plane shutter cameras (which is most cameras). Either you stop down the aperture, use ND filters, or use HSS to get your exposure. HSS isn't very useful outdoors as it needs a lot of power. Using a small light like a speedlight limits this to barebulb use only and you can only fire off a limited amount of shots before the system overheats.

Are you going to remote control your strobes?
If so you are going to be to need a remote trigger. You have get one that's compatible with your lights. Usually the manufacturer of a light has a specific trigger that works with their lights and particular cameras (for TTL/HSS compatibility). On more advanced remotes you can control power, groups, HSS/TTL/Manual modes, modeling lights, and sounds. On the most basic level, if the flash has a sync port, it can be trigger by remotes that can connect to that port. Using a sync port is very basic functionality from many decades ago and those usually don't allow HSS or TTL because those need more communication with the camera and flash.