Freezing motion is relatively easy... Showing the details of what the eye cannot see in a split second is rather cool, and maybe the most exciting part of capturing moving subjects. I often work with performers so I am used to capturing movement, the idea here is to show you how to get great results by following a few basic rules.
So I assume you are shooting in manual mode!
Basically, there are 2 ways of freezing motion, with your shutter speed or your flash.
1/ When shooting outdoors, with the sun as your main light or in an environment with lots of light, your shutter speed will be the main ingredient to freeze your subject. I usually start at around 1/500s, keep my ISO as low as possible and start at a F-stop around 5.6.
Lynne Karina Hutchinson (London)
5D Mark IV - 35mm f1.4L II 1/500 F5.6 ISO 1000 - 35mm
Injy Pina and Allegra (La cité du vin - Bordeaux)
5D mark III - 24-70mm f2.8L II 1/800 F7.1 ISO 160 - 50mm
If you are using a flash using the HyperSync or High-Speed Sync mode of your flash to go beyond the 1/200 or 1/250 sync limit... If you don't know what HSS or HS is:
HS and HSS explained :
Hypersync (Broncolor) : https://news.broncolor.swiss/tutorials/hypersync-easily-explained-by-fabio-gloor-part-1/
Mohana Rapin (Jardin Botanique de Genève)
5D mark III - 24-70mm f2.8L II 1/500 F6.3 ISO 250 - 24mm
Gillian Leopold (EIlen Roc - Antibes)
5D mark III - 11-24mm f4L 1/2000 F4.5 ISO 500 - 15mm
Alizee Agier (Antibes)
5D mark III - 24-70mm f2.8L II 1/2500 F8 ISO 400 - 61mm
I believe that going under 1/500s might not be enough to freeze movement. Depending on how fast your model moves, going above 1.500s will increase your chances of having a sharp image. Your ISO and aperture will depend on your tastes. For example, if you wish to have a better background separation, simply use a low f stop but remember, you are working with a moving subject. Using a narrow depth of field makes it harder to nail focus.
If you are shooting indoors or at dusk and you don't have a lot of light, don't be afraid to increase your ISO. Having a high shutter speed will decrease the amount of light touching your sensor. I sometimes go up to ISO 3200 to compensate.
Mercedes Flores (Dome de la Grave - Toulouse)
5D Mark III - 24-70mm f2.8L II 1/320 F2.8 ISO 3200 - 24mm
2/ When using your flash to freeze movement, keep your shutter speed at 1/200s or lower and let your flash do the job. The brief burst of light, the short flash duration, will be enough to freeze the action! So now we are o longer in HS or HSS mode, we rely on the short burst of light to capture movement.
Let's make it simple, how does your camera capture an image? Your shutter opens and closes, and while it's open, your sensor captures light and creates your image.
I work with Broncolor lights, and when I use the "Speed" mode that enables short flash durations (check your gear to see how you can achieve this), the flash can be as short as 1/19000s! This means that if your camera is set at 1/200s after your flash has fired your shutter will still be open for a brief moment and it will continue to capture your photo and whatever is going on in front of your camera.
So your success will depend on the available light. If the location you are working in is dark, if it is poorly lit, you will have great results. If there is a bit of light around, coming from any light source you might have motion blur in your image.
So The decision is up to you, are you willing to keep these blurry parts in your shots?
Here, by killing the ambient light, I manage to have the right balance to better freeze the action.
Cyd Sailor (Base Sous marine - Bordeaux)
5D Mark III - 24-70mm f2.8L II 1/200 F2.8 ISO 640 - 70mm
Anna Romanova (Palais de la bourse de Lyon)
5D mark III - 24-70mm f2.8L II 1/200 F8 ISO 800 - 24mm
Don't forget to play with your f stop and ISO to correctly expose and balance your shot.
Célie Juston (Grenoble)
5D mark III - 24-70mm f2.8L II 1/500 F4.5 ISO 320 - 33mm
I said earlier that under 1/500 might give you blurry results... I tried a few times and depending on the amount of light you let in you, and on how fast your subject moves, you can still get great results with a slower shutter speed.
Here during the day with flash
Candice Dupont (Toulon)
5D mark III - 16-35mm f2.8L II 1/200 F5.6 ISO 100 - 16mm
Without flash
Valentina Pierini (Rome)
5D Mark III - 24-70mm f2.8L II 1/320 F4.5 ISO 125 - 24mm
Indoors with flash
Anna & Ricardo (Palais de la bourse de Lyon)
5D Mark III - 24-70mm f2.8L II 1/200 F8 ISO 800 - 24mm
And here all the shots used for this sequence were shot at 1/200s! Katarina Stosic (Le Havre)
5D Mark III - 24-70mm f2.8L II 1/200 F7.1 ISO 320 - 38mm
Letting motion blur in your shot is not a bad thing... I sometimes play with it, like in this shot where I didn't want the ball to be tack sharp.
Gautier Fayolle (St denis)
5D mark III - 24-70mm f2.8L II 1/200 F5.6 ISO 160 - 45mm
I said it before Aperture is an important element you cannot overlook. Outside having motion blur or not, you want a focused image. So using a high f stop will ensure a focused photo... I still use 2 simple techniques to focus on my subject:
A/ I decide where I want to catch my subject and set focus before the action. This demands a precise execution for both the photographer and the performer. I usually do this when I have a specific composition in mind, and when I work on a tripod.
B/ I use AI servo and follow my performer and blindly rely on the continuous autofocus of my camera.
So when do you use Flash, when do you use your shutter speed to freeze motion? Only you can answer this question. I choose the shutter speed often over my flash when shooting outdoors and use my flash when I work indoors. But this is not systematic as every situation is unique and different.
Know exactly what you want to do, with or without flash, with a bit of motion blur, a lot or without, with a shallow or wide depth of field, and so on... Then experiment, try, fail and repeat! You will find your style and feel comfortable with time. Have fun building your own creative tools!