Is Auto-Metering the Same as TTL?

If you've seen some of Godox's micro and retro speedlite flash ranges, like the Lux Cadet, you might have spotted their Auto-Metering functions to help you get the best level of exposure for your flash and image, much like TTL. But is it the same?

Are Auto-Metering and TTL the same?

To put it simply, no.

TTL and Auto-Metering, while producing similar effects, work different ways, and will produce a different effect on the light.

How are Auto-Metering and TTL different?

Auto-Metering or Automatic mode is a function built into the flash itself and doesn't communicate with the camera at any point other than when triggering the flash to fire via the shutter. This works through a sensor at the front of the flash that measures the light independently, and calculates the best exposure for the image.

Most flashes with an Auto-Metering or Automatic function also have the ability to turn off to Manual mode instead so you can set your own settings. 

Auto Metering can be found on flashes like the Lux Cadet, the Lux Junior and more. 

Find out more: Introducing the iFlash Range

The Lux Cadet with the auto-metering light sensor circles

TTL stands for "Through-The-Lens" and is your Flash’s “Auto-Exposure Mode. This is built-in to your camera via a light meter that measures the amount of light coming through the lens. With that information, your camera then tells your flash how much light to output to get what it thinks is the correct exposure.

TTL Auto exposure can come in handy under certain situations, such as if you have your flash on camera on a shoot where you are constantly moving around, or if the lighting conditions are constantly changing, such as shooting outdoors, where the Sun is going in and out.

TTL is often found on flashes like the AD Range including AD200Pro II, and on most of the Godox range of Speedlites like the V100. 

What does this mean for me?

If you've got a hotshoe flash that uses TTL, you must make sure the model of flash is designed to be compatible with your camera model. If you try and use a Canon camera with a TTL flash designed for Nikon for example, TTL functions won't work. 

Non-hotshoe TTL flashes instead need a TTL compatible trigger instead, that the communicates with the camera for them.

Manual flashes, and those with Auto Metering functions are designed with universal hotshoes, meaning that you can use the one model of flash with any camera brand provided it has an appropriate hotshoe. This is because Manual & Auto Metering flashes don't have to communicate with your camera's metering to work. 

How to use Auto Metering

1. Set the mode to “A” (Auto):
   • Use the retro-style mode switch to set the flash to “A” instead of “M” (Manual).
     
2. Set your ISO and Aperture on the camera:
   • Match the ISO and aperture or F-stop values on your camera to what the flash expects.
   • The Lux does not auto-read the camera settings; you must manually align them.
3. Flash calculates output automatically:
   • The flash uses a thyristor-based auto-exposure sensor to fire at the necessary output level based on ambient reflection.
   • Once in Auto mode, the flash uses its built-in sensor to measure reflected light and automatically adjusts the flash power to deliver a proper exposure for the set aperture and ISO.

Check out our table below to find out which flashes have TTL, and which are Manual or Auto Metering so you can pick the right equipment for your needs. 

Image	Model	Hotshoe / Trigger	TTL / Auto Metering / Manual Only
	Lux Junior	Hotshoe Flash	Auto Mode & Manual
	Lux Senior	Hotshoe Flash	Auto Mode & Manual
	Lux Cadet	Hotshoe Flash	Auto Mode & Manual
	Lux Elf	Hotshoe Flash	Manual Only
	Lux Master	Non-Hotshoe/Needs Trigger	TTL Supported
	iM20 iFlash	Hotshoe Flash	Manual Only
	iM22 iFlash	Hotshoe Flash	Manual Only
	iM30 iFlash	Hotshoe Flash	Manual Only
	iA32 iFlash	Hotshoe Flash	Auto Mode & Manual
	iT30Pro iFlash	Hotshoe Flash with Receiver Built In	TTL Supported
	V100 Speedlite	Hotshoe Flash with Receiver Built In	TTL Supported
	V1 Pro	Hotshoe Flash with Receiver Built In	TTL Supported
	V860III	Hotshoe Flash with Receiver Built In	TTL Supported