Depending on the set location, the ideal illumination of a green screen requires more or less sensitivity and sophisticated lighting technology – which doesn’t even have to be expensive, but must be used intelligently. A staked-out indoor set with a filigree focus object as a placeholder for a possible protagonist serves as an example backdrop. The aim is to illuminate the green screen as ideally as possible around the protagonist’s stand-in and, in the best possible case, to illuminate the entire green screen – even around the curve – in an ideal way. In the event that the protagonist moves and the camera follows with a dolly or a camera pan. The sample devices tested were equipped with iOS.
Intuitive operation
When the app is started – regardless of whether iPhone or iPad – the camera on the back is accessed by default. The set appears in grey with a few green areas. The placeholder is visible in the centre. The resolution of the set varies depending on the device, so it is advisable to use the latest devices that have high-resolution cameras. Firstly, we recommend taking a look at the screen and, of course, at the setting options that the user can influence to improve the key.
At the top of the screen is a menu bar with four selection modes. Users can change the cameras on the respective device, i.e. switch from back to front mode. The latter is a great advantage if the lighting control unit is further away or there are only two people on set and no placeholder is available. This allows two set employees to adjust the studio lighting. There is also the option to mirror the active video signal of the respective camera horizontally or vertically. There is also a menu bar at the bottom of the screen with just under two handfuls of selection options. The possible quality settings are lined up on the left. There are three modes in total, ranging from Low to Mid and High.
Directly next to this are the possible channels to which the key is to be applied. These include the classic RBG channels and a pure brightness channel Y, the luminance. It is also possible to define a focus target using the neighbouring button called “Target”. Next to this is a button for automatically determining the brightness ranges. If a specific brightness range has been selected, an auto-exposure lock can be set and the brightness band is displayed.
Simple handling
During our test, two set employees were available for the accurate light setting of the set. One operated the respective iOS device, the second the light control panel. The first step consisted of illuminating the green screen according to the best possible visibility, strategically positioning the available light sources and setting a basic brightness. One of the available tripods, which was available for other equipment, was used as a placeholder. The work began by taking different positions from the front of the A-unit camera and setting the desired quality. The quality is concerned with the representation of visible or recognised light frequency bands. Low corresponds to 2-stops, medium to 1-stop and high to ½-stop. Depending on the setting, more bands are displayed accordingly.
The first test was carried out with the Low setting and immediately showed a result that required very little correction. Only one spotlight on the far right had to be adjusted upwards in terms of intensity until the green screen was virtually ideally lit for chroma keying. This was based on the channel setting for the green colour channel.
The second test run examined the Medium quality setting, which displays significantly more bands than the Low setting. From now on, the fine tuning began. Any frequency band can be selected at the touch of a finger, and all the same brightness values are displayed with the colour of the underlying or selected channel. Significantly more improvements were needed at this point. Instead of adjusting the brightness of just one spotlight, the spotlights now had to be rotated favourably for ideal, comprehensive illumination. The app works extremely accurately for the fact that it is an app for consumer devices. Detail-loving film-makers and perfectionists may get lost in the fine-tuning, as the High setting for a consumer device measures the amount of light in the reflection very accurately.
The second test example took considerably longer than the low quality setting. Nevertheless, the chroma key was acceptable in the low range. Problems occurred with fine strands of hair and small protruding hairs within a close-up shot. Close-ups should always be measured at the highest possible quality level. And in this case, only the green screen directly around the protagonist was illuminated very cleanly, as the lighting system would have required twice as many spotlights for fine illumination over the entire area. Medium mode was selected for the entire illumination of the stationary green screen area, which made it easier to quickly obtain a suitable lighting setup.
If a specific brightness band is marked as the desired band by clicking on it, the brightness level can be fixed. This makes work much easier if person 1 systematically runs the green screen and person 2 controls the lighting system. Control means adjusting the brightness and fine-tuning the beam angle.
Rating: Highly recommended
The conclusion of the test scenarios is consistently positive. There is hardly anything to criticise. Of course, there were points that were not always entirely satisfactory, but these had more to do with the underlying hardware. As mentioned at the beginning, new devices should be used that have excellent visuals, good computing power and a larger screen. The app made an extremely good impression on tablets. Mini smartphones can be used, but working with the app is more fun and allows for better fine-tuning with larger devices.
There is one small drawback – which can also be seen as positive. Perfectionists will really enjoy the app, but the quick light setting can also turn into a symbolic Ravensburger light puzzle in no time at all. However, with a good deal of turning experience, good lighting should be set up in a perfectly acceptable time frame.
One point that was also negative was the price difference between Android and iOS. In short: Apple users pay a little more. However, the evaluation of the price difference has nothing to do with the function of the app and is therefore not evaluated in more detail. All in all, the Green Screener is a solid app and should not be missing from the digital repertoire of filmmakers.
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