After the M4, Leica started with embedding their cameras with light meters, or Leica TTL. Here’s everything you need to know about them.
What is TTL in Leica?
TTL stands for trough-the-lens and refers to the capacity of the camera to judge the exposure from inside the lens as opposed to an external light meter. This eliminates the need to have an extra accessory and is a more accurate way to judge light because it samples the subject directly from the lens.
While that might not be much of a “feature” nowadays with live view, back then when using film cameras you either had to eyeball the exposure or use a Leicameter or similar. The first Leica to have a built-in light meter is the Leica M5.
Is Leica M6 TTL?
TTL can refer to either the light metering capacity OR it can also refer to the camera’s capacity to pass on information to an attached flashlight (TTL flash). So the Leica M6 has TTL metering (in other words, has a built-in light meter like the M5) but if you want to use automatic flash only the Leica M6 TTL has that capacity.
Is Leica M7 TTL?
Yes it is. Just like the previous M6 TTL, the Leica M7 has both trough the lens metering AND trough the lens flash.
Leica TTL Comparison
| Specification | Leica M7 | Leica M6 TTL | Leica M6 | Leica M5 |
|---|---|---|---|---|
| Battery | Lithium (2), 3V each | Silver oxide (2) or 1.55V oder Lithium (1), 3V | Silver oxide (2) or 1.55V oder Lithium (1), 3V | Mercury Oxide (1) 1.35V |
| Metering Cell | Silicone Photodiode | Silicone Photodiode | Silicone Photodiode | Cadmium Sulfide photoresistor |
| Metering Diameter | 12mm | 12mm | 12mm | 8.5mm |
| Metering range cd/m2 | 0.03 to 12,5000 | 0.03 to 12,5000 | 0.06 to 12,5000 | 0.03 to 12,5000 |
| Exposure value | ISO 6 to 6400 | ISO 6 to 6400 | ISO 6 to 6400 | ISO 6 to 3200 |
| SS Manual | 4 secs to 1/1000, B | 1 secs to 1/1000, B | 1 secs to 1/1000, B | 1/2 secs to 1/1000, B |
| SS Automatic | 32 secs to 1/1000 | NA | NA | NA |
| Aperture | f/1 to f/32 | f/1 to f/32 | f/1 to f/32 | f/1.4 to f/32 |
How does Leica TTL work?
If you’ve ever wondered WHY on earth does the Leica M5 doesn’t look like any other M camera, that’s because of the TTL metering. There’s a little “arm” inside the camera that meters the light and that takes a lot of space, making the M5 necessarily larger than it’s other siblings.
From the M6 however, another way was used. In front of the shutter is a large white spot that a light meter is constantly aimed at and reads. For the Ms with flash TTL two photocells are used at opposite ends.