Comparison Yongnuo YN720 vs Yongnuo YN686EX-RT

— Autofocus illuminator. The flash has an auxiliary illumination function for the camera's autofocus system. Modern cameras overwhelmingly use the so-called passive autofocus systems that have one serious drawback: very low efficiency in low light and/or low contrast of the object being shot. The autofocus illuminator is designed to solve this problem: before focus, the scene is illuminated by a separate lamp, placed, in this case, directly in the flash body. This provides enough light for normal autofocus operation. Most often, backlight lamps give light with a characteristic reddish tint, however, in some advanced models, infrared illumination is used — invisible to the eye, but perceived by the camera. In addition, illumination systems can use a special light pattern instead of a solid beam, which further simplifies the task of autofocus systems. Anyway, the presence of this function is especially relevant given the fact that the flash is often used as a light source in low light.

— Control on the camera. The ability to change the settings for the flash using the controls of the camera itself, to which it is connected. In some cases (for example, with a wireless connection), this is much more convenient than switching attention from the camera to the flash.

— Automatic zoom. The ability to automatically change the angle of dispersion of the flash light. For the angle of disper...sion, see the relevant paragraph above, but here we note that this function provides synchronization between the flash and the lens: when the focal length of the lens changes, the angle of dispersion automatically changes. This provides the most effective illumination of the scene and at the same time relieves you of the need to manually re-adjust the flash to a changed angle of view each time.

— Manual zoom. Possibility to change the flash spread angle (see "Light spread angle") manually. This function expands the possibilities for "fine" tuning of work parameters and allows you to set parameters that are not available with automatic zoom (see above). In addition, it will be useful if you have to use several prime lenses with different focal lengths — the flash can be easily adjusted to each of them.

— Wireless control. Ability to wirelessly connect the flash to the camera or to another flash as master/slave (if available, see below). The format and specific features of such a connection may be different: wired connection, IR channel, radio, etc. Wireless control is indispensable if the flash must be placed away from the camera; it also makes it easier to create multiple flash systems for optimum lighting. These features are especially useful for studio shooting (although it's not limited to this).

— Work in master mode. The ability to operate the flash as a master flash for a system of multiple flashes. The entire system is controlled through the master flash, the operation parameters of the slave flashes are set, and the command to fire is given (note that the master flash itself may not fire at all). If you plan to shoot using a multi-flash system, you will definitely need a model with this function — without it, creating a system is impossible. Of course, master and slave flashes must be mutually compatible; this point should be clarified separately.

— Work in slave mode. The ability to work as a flash as a slave in a system of several flashes. In this mode, the device is connected to the master flash and fires on command from it. For more information on flash systems, see "Master Operation" above.

— Diffuser. The colour of the diffuser supplied with the on-camera light source (see "Type"). Colour can be: orange, white, pink or yellow.

A diffuser is a special filter designed to scatter light from individual LEDs, and also, in some cases, to give it a certain colour and change the colour temperature.

— Radio synchronizer. A device designed to wirelessly control a flash or a set of flashes (if each has its own receiver). Usually a separate module installed in the hot shoe; on command to fire, this module sends a radio signal to all receivers tuned to it, ensuring synchronous flash firing. At the same time, some models of luminaires with such a function are capable of receiving via the radio channel not only the start signal, but also the operating parameters (primarily the duration and power of the pulse).

The type of element used to power the flash.

— AA. Powered by replaceable cells of standard AA size, known in everyday life as "finger-type batteries". The main advantage of such a power supply is the ability to quickly replace “dead” batteries with fresh ones: the replacement process takes one or two minutes on the strength (whereas for the built-in battery, charging is often the only option, which takes a long time). AA elements are sold almost everywhere. On the other hand, with such a power supply, you will either have to regularly spend money on disposable batteries, or separately purchase AA batteries and a charger for them; anyway, additional costs cannot be avoided. Another drawback is the dependence of the battery life of the flash on the quality of the batteries: when using cheap cells that are not designed for serious “loads”, the number of pulses per charge can be significantly (several times) lower than stated in the specifications. However, these shortcomings are generally not critical, and this type of food has become quite widespread. Most modern flashes use 2xAA, 4xAA, 6xAA, depending on power.

— AAA. Powered by replaceable cells (batteries or accumulators) of standard AAA size, known under the informal name "little finger" or "mini finger". Such elements are completely similar to the above-described AA and differ only in smaller...sizes, which makes it possible to reduce the dimensions of the flashes themselves accordingly. However, for a number of reasons, they are used less frequently. Mostly 2xAAA are used.

— Battery. Powered by its own original battery, which is not related to standard sizes, and sometimes also non-removable.

On the one hand, in some aspects, such a power source is much more convenient than replaceable batteries. First, it initially comes in a kit, and the device is ready to work out of the box. Secondly, in the same kit there is usually a charger (or the flash itself connected to the network plays its role). Thus, when using it, you do not need to spend money on buying batteries — everything you need is already included in the kit. In addition, we note that special batteries are often more capacious, more powerful and at the same time more compact than replaceable cells; besides, they are easier to "fit" into the overall design of the flash and reduce the size (although the built-in batteries are different). On the other hand, such power has one key drawback: when the charge is exhausted, the battery will most likely have to be recharged, and this takes time and the availability of an outlet (or other external power source). In the best case, if the battery is removable, you can purchase a spare for it and keep it ready — but this feature is not available in all models.

In light of all this, the main field of application for batteries is "flashlights" for video — sources of on-camera light (see "Type"). It is in such devices that high capacity is of key importance: you have to shine "constantly and a lot", and with a high power of the light source, batteries cannot effectively cope with this task.

— CR123A. Replaceable cylindrical batteries, slightly thicker and noticeably shorter than AA batteries, have a diameter of 17 mm and a length of 34.5 mm. They also differ in operating voltage — 3 V. Some time ago they were quite popular in photographic equipment, but today they are extremely rare.