Speedlite channels are a way of triggering the speedlite from your camera using an RF wireless trigger. The exact channel is not important as long as each trigger and receiver is set to the same channel. Groups allow you to control the setup and triggering of a number of flash speedlites from your camera-mounted speedlite trigger. When they are properly set up you will then be able to adjust the power of each speedlite remotely from the camera – allowing you to concentrate more on the actual photo-taking rather than dashing around from one speedlite to another.
The best way to describe how channels and groups work in flash photography is to separate them out. First, let’s deal with channels…
What are Channels and How are They Used in Flash Photography?
Channels are used in Flash Photography to ensure the speedlites will be triggered reliably and only by the wireless transmitter.
A wireless flash trigger system is a radio transmitter together with a series of radio receivers – one receiver for each speedlite. They use a digital coding system to ensure the receivers only trigger when the transmitter sends a valid signal. False triggering is mostly eliminated.
Just like any radio system, the receivers will only receive the signal when they are switched to the same channel as the transmitter. The RF603 has sixteen channels available. Mostly it doesn’t matter which channel you select as long as all units are switched to the same one. The switches in the RF603 are hidden away inside the battery compartment. You don’t need easy access to them – they are basically set-it-and-forget-it. I have never changed these switches in the RF603 units I have. They came pre-configured for Channel 0 and I just left them there. I have never had any triggering issues with them.
Now I said earlier that it mostly doesn’t matter which channel you select. This means there could be times when it does matter. This is why Yongnuo provided 16 channels in the RF603.
Have You Ever Seen Your Speedlites Trigger When You Are Not Firing Them?
This could be because of local interference. Someone else could be nearby and using the same system set to the same channel as you. In this case your receivers will trigger the speedlites on command from his transmitter.
This is when you would change your system to a different channel. You have 15 more channels to choose from – just make sure all your units are changed to the same channel.
Tip: Do a quick test-firing of your system after changing the channel before reassembling your lighting setup again – just to be sure everything is working.
Alternatively, if you are concerned this situation may arise at sometime then change the channels right now – before you start shooting. Most people will leave the switches on the default settings when they get the units home. They will test-fire them and then start using them immediately. There is no reason the change the channel. But you could change the channel to, say, channel 11 (you choose). The likelihood of someone else running the same system nearby and also having his set to the same channel as you is now very remote.
What are Groups, and How are They Used in Flash Photography?
Groups are used in Flash Photography to allow the photographer to change the Speedlite settings remotely without leaving the camera position.
The RF603 Does Not Support Groups
The RF603 is a simple remote trigger system. One unit is nominated as the transmitter and the others are nominated as the receivers. The function of the RF603 units is to remotely trigger the speedlites – nothing more. The use of groups in Speedlite Photography is way beyond the capabilities of the RF603. For this, we will discuss groups using the YN560Tx.
The YN560 Tx does Support Groups
The YN560Tx, when used together with the YN560iv speedlite becomes a two-way speedlite communications system that supports channels and groups. The indicator for this is the (blue) Link light on the YN560iv. Every time you adjust a setting on the YN560Tx, the Link light will flash – indicating there has been an exchange of information. i.e. The YN560Tx has told the speedlite what settings to update and the speedlite responded that it has done that.
Groups is a Poor Choice of Word
Groups is an unfortunate choice of words, but one that we’re stuck with. I normally associate groups with a collection of people or things. In a world where we can have a gaggle of geese, a troop of monkeys, or a mutation of thrush, why call a group of speedlites a… group? A group usually means a sizable number. But in flash photography a group is normally one transmitter and one receiver. And this has been my confusion in the past – I could never see the reason for calling one wireless flash receiver a group. I also could never see why I would want to separate flash units into groups when I would want them all to trigger at the same time. You know…. like in a group!
But this was my misunderstanding, and as soon as I got my head around it I could see how it worked (and try to get past the designation of groups).
So let’s see if I can explain it in my words to remove any confusion for you.
A Group – Defined
This explanation will go easier if we start with the definition of what a group is in flash photography.
a group is when one transmitter is connected to one light source.
Let’s rename things a little… in the YN560Tx there are six groups – A, B, C, D, E, F. Let’s make it simple by dealing only with groups A, B, and C – we will rename the groups…
- A – Main Light
- B – Fill Light
- C – Hair Light
On the YN560Tx there are three modes for the groups. These modes can be set individually for each group.
- A – Main Light M(anual)
- B – Fill Light — (OFF)
- C – Hair Light — (OFF)
The ensures that when you trigger the speedlites, only Group A will flash – the others are disabled.
Set the lights where you want them to be.
Set your speedlites on light stands or propped against a vase, etc. according to how you want to light your model. Set them all approximately the same distance from the model – it makes things easier to begin with.
Adjust the Main Light
Take some shots and adjust the intensity of Main Light to give you a good exposure for your camera setting. You’re mainly wanting to ensure there are no burnt-out highlights anywhere in the frame.
Adjust the Fill Light
- A – Main Light — (OFF)
- B – Fill Light M(anual)
- C – Hair Light — (OFF)
Now, when you trigger the speedlites, only Group B will flash – the others are disabled.
Take some shots and adjust the intensity of Fill Light to give you a good exposure for your camera setting. You’re mainly wanting a more gentle light here – it is only required to lighten the shadow areas so they don’t appear as completely black in the image.
Adjust the Hair Light
- A – Main Light — (OFF)
- B – Fill Light — (OFF)
- C – Hair Light M(anual)
Only Group C will flash when you trigger the speedlites now. The other two groups have been disabled.
Take some shots and adjust the intensity of Hair Light to give just a slight illumination to the model’s hair. The purpose of this light is to show the top/back of your model’s head against the darkest of backgrounds.
Now Combine All The Lights
- A – Main Light M(anual)
- B – Fill Light M(anual)
- C – Hair Light M(anual)
This means all the lights are fully-functional.
Now you should take some shots. Start adjusting light intensities one-by-one until you see a look you like. I’m not going to discuss how to achieve the look you’re after – this article is only to discuss the technical aspects of doing it.