Mirrorless Camera Flash

Accessory or key component? This is the question that many manufacturers have posed when it comes to mirrorless DSLR flash.

The main way that mirrorless cameras are able to reduce their size is due to the removal of the system of mirrors inside the camera that reflect light from the lens to the viewfinder.

The second way that many manufacturers have kept size and weight to a minimum is by leaving off a built-in flash.

Built-in vs. External

If you're not familiar with flash terminology, there are two main types of flash that you can use with a mirrorless camera:

  1. Built-in — these small flash units pop up from the top of the camera as needed to add more light to dark scenes. They are not very powerful, and often cause red-eye in portrait subjects.
  2. External — an external flash is a larger flash unit that attaches to a plate on the top of the camera called a hot shoe. External flashes can be very powerful and have lots of features that can be customized.

Not all mirrorless cameras come with a built-in flash. Many of the smaller cameras leave off the built-in flash and provide a small external flash that is either packaged with the camera or that can be purchased as an accessory.

The question that you have to ask yourself is whether you want a built-in flash at all.

The main benefit of built-in flash is convenience: it's always attached to the camera. You don't have to always tote around a separate flash unit in the off chance that you'll need to use it.

However, built-in flash comes with some drawbacks:

  • Low Power — because of their small size, built-in flash units are never very powerful and can only light subjects that are very close to the camera
  • Red Eye — due to the small distance between the lens and the flash, you'll often get red eye with portrait subjects
  • Flash Direction — the light from a built-in flash unit always comes from the same direction as the camera (head on)

All of these limitations are overcome when you use an external flash - the main drawback is that you have to remember to take the flash with you.

External flashes can also cost quite a bit of money, depending upon the power of the flash and the number of features that the flash includes.

Just because you are using a flash that is not built-in, don't feel that you'll have to go all manual with it. All external flash units operate in full auto mode, just like a flash that is built-in to the camera. You just have to point and shoot, and the flash will figure out how much light you need for a good image.

Flash Jargon: Guide Number and Sync Speed

Whether you're using a built=in flash or an external one, two limits will be applied to your mirrorless DSLR flash:

  1. The flash-to-subject distance
  2. The maximum shutter speed

The power of all flash units is listed in the spec sheet by a value called a guide number.

Assuming that other camera settings remain constant, a higher guide number means that the flash can light subjects that are further away.

Remember: built-in flash units are not all that powerful and have relatively low guide numbers. This means that you have to be up close and personal with your subjects to light them with built-in flash.

If you'd like to distance yourself from your subjects but still get good exposures, you'll need a flash with a higher guide number.

So distance is one limiting factor, the other is the shutter speed you can use.

When you're using flash with a mirrorless camera, you can't use any old shutter speed you want. The maximum shutter speed will be limited - often between 1/160th and 1/250th of a second - due to an upper threshold called the sync speed.

If a camera has a slow sync speed, it just means that you won't be able to capture shots of fast-moving subjects (which require faster shutter speeds) when you're using a flash.

Bottom Line

If you plan to take most of your photos in natural light, then don't worry too much about what sort of a flash a camera uses.

However, if your primary reason for getting a mirrorless camera is to take pictures of friends at dimly lit parties, then you're going to use the flash constantly.

While built-in flash certainly has an element of convenience, you will get MUCH better results if you're willing to spend some extra money on an external flash.

Yes, you have to lug around a large, heavy flash but that's a small price to pay for spectacular photos, isn't it?