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Through-the-lens metering (TTL) is a feature in many modern cameras that allows the user to measure light levels through the lens that will capture the picture.

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24
votes
1answer
10k views

What are the differences between E-TTL, i-TTL, and P-TTL?

Canon, Nikon and Pentax each have their own TTL flash metering systems, respectively E-TTL, i-TTL, and P-TTL. They all use a weak preflash that is metered and used to calculate flash power level ...
19
votes
4answers
17k views

What does TTL mean?

I'm new to photography and I see the term TTL all over the place. What does it mean? And how do I use it to make my pictures better?
5
votes
5answers
324 views

What are the most important features to look for in a low budget hotshoe flash and why?

When trying to get started with flash photography, there are a lot of new options, features and techniques that a photographer gets thrown in to. When starting on a budget, what features will give a ...
4
votes
3answers
983 views

How do TTL flash metering systems calculate how much power is needed?

Does anyone know how TTL calculates the amount of power to put in after the preflash is done? I understand that the value is somewhat brand specific, but what is the general logic? Because if you ...
3
votes
1answer
467 views

Why is my Metz 58 AF-2 using long shutter values when my Canon 60D is in Av mode?

About one year ago I bought a Metz 58 AF-2 for my Canon 60D. Because of a lack of free time to experiment with automatic functions, I have used it only in manual mode with other manual flashes, ...
13
votes
3answers
661 views

What was my flash power?

When I am using a Canon flash in the E-TTL mode, how can I tell which flash power the E-TTL magic chose? For example, if I got a correct exposure in the E-TTL mode, can I easily choose the same flash ...
8
votes
7answers
5k views

Advantages of TTL over manual mode when using speedlites

Yesterday a user on stackexchange asked me why do I prefer manual over TTL when working with speedlites. I use them mostly off-camera and I've developed a kind of a workflow where I do not walk back ...
3
votes
4answers
2k views

Why is manual flash at the lowest power stronger than the TTL result?

I have a 500D with the 430EX II flashgun. I've taken two pictures with the camera in manual mode, one with the flash in ETTL mode and then in manual mode with the power to 1/64 and the flash exposure ...
2
votes
2answers
132 views

Why is flash TTL metering independent from ambient light metering? [duplicate]

In other words, why is ambient exposure metering independent from TTL metering? Let's say Im taking a picture in a room that has a window and some daylight is getting in,and Im shutting in P (program ...
10
votes
1answer
508 views

Why isn't TTL metering accurate when using a non-electronic lens?

I recently bought a Lensbaby lens and I played with it a lot. Then lens is awesome but I have one big and annoying problem and is that TTL metering fails miserably when using P, TV and M modes. I ...
6
votes
2answers
2k views

Are there any radio flash triggers capable of P-TTL?

All the popular radio TTL flash triggers, like PocketWizard or RadioPopper, seem to be only available in Nikon and Canon flavors. Are there any models capable of transmitting Pentax P-TTL data?
4
votes
2answers
146 views

Does a flash's TTL automatically adjust as I change its location?

I just bought a radio trigger for my flash. I was just wondering if I understood TTL correctly, as I move the flash around and changes the distance does TTL automatically try to compensate (assuming ...
3
votes
5answers
322 views

Does TTL by definition overexpose your subject? [duplicate]

So I'm only beginning to learn TTL but from what I understand the preflash determines how much flash power to use. But the camera already exposes everything correctly for the entire scene (assuming ...
2
votes
3answers
228 views

If TTL only preflashes once, how does it get correct exposure immediately after?

If I understood TTL correctly, say you are in M mode with a camera and you have intentionally underexposed. The flash in TTL mode theoretically would try to add enough light to correctly expose the ...
2
votes
2answers
129 views

Does auto mode of flash metering have any advantage over TTL?

Does auto mode of flash metering have any advantage over TTL? One advantage that I can think of is the absence of a pre-flash in the auto metering, which can make some people blink. (But I rarely use ...
1
vote
5answers
314 views

What exactly does TTL flash sets its power to?

I understand that TTL flash means the flash will preflash and try to calculate the right exposure for that particular scene. That part makes sense, but what exactly is the "right exposure"? Does it ...