Types of Flash

TTL Flash

The TTL flash are the latest in flash. What is TTL? Means'' Through the Lens'' or'' through the lens.''

The process of calculating the required amount of light gets through the lens unlike the Auto mode is done with a photocell on the flash.

TTL mode functions differently in the chambers analogies (SRL) and the digital (DSLR).

In analog cameras when the light hits the film part of this light is reflected to a sensor that controls the flash.

When this sensor believes there is enough light to expose the photo correctly, short flash.

In digital cameras this is not possible because the CCD or CMOS sensor does not reflect too much light. So how does it work? The flash will fire pre-flashes before exposure.

It measures the light coming through the lens and used to estimate exposure. This happens so fast that the human eye perceives it. We only see a flash shot.

The first flashes were Canon E-TTL and the improved system is E-TTL II. In the first Nikon D-TTL system was and the improved system is i-TTL.

In the pictures below you can see a flash of Canon TTL and Nikon i-TTL.

 

The TTL flash has several advantages. The first is that we can choose the aperture you want according to the depth of field you want to achieve.

This means that we do not have to worry about calculating distances over every time we make a picture.

Of course, as mentioned above, there will always be a minimum and maximum distance to which we can take pictures with a given aperture. This is because the flash.

Another advantage is that the sensor is only going to cut the flash and we frame what we're shooting this well lit. So if there is something in front of our object that does not appear in the photo the flash is not going to consider.

The major disadvantage is that the TTL flash are quite expensive. But if we are really flash photography and is an element that we will be using consistently, then it is worth the investment.

In the picture above we can see the display of a flash TTL-At the top we can see that is being used in TTL (also Auto and Manual).

In the red box can see that sensitivity is being used, in this case, ISO 200.

In the yellow box can see the aperture: f/5.6.

In the blue box or we can see the zoom lens is in use. In this case a 200mm.

And we can see the green box in meters, the minimum and maximum distance at which we can put the flash for the main object goes well exposed.

In this case is 9 to 13 meters. If we put the flash closer to the object's out overexposed and if we put the flash farther away the object is exposed to sub-out.

To use a TTL flash we have to have a camera that works with a TTL flash. They must be compatible.

When connecting the flash to the camera it reads all the information we put into the camera. So reads the iris and lens we are using. So it appears in the viewfinder.

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