What are the photography skills of digital movies?

What are the photography skills of digital movies? In order to help you fully understand this problem, I have compiled the photography creation skills and related contents of digital movies for you, hoping to help you!

Photographers in the digital age

With the development of digital movies, there will even be late directors in the future. Now, the pre-production and post-production of sound have begun to separate. In the early stage, only the actual sound was included, and in the later stage, another sound engineer did surround sound mixing. Will there be such a situation in terms of pictures, where the photographer is only responsible for the early picture collection and the later director is responsible? But in any case, the photographer's first task is to collect without flaws on the spot. Therefore, it is necessary to make the focus not wrong, not to waste the dynamic range of CCD, and not to lose the hierarchy of the scene, so that the brightness of the scene falls within the dynamic range of CCD optimally, and at the same time, to make the tone of each shot conform to the creative style of the film, so as to provide the best original image for post-production. This is the first duty of a photographer.

Misunderstanding of gamma curve

The equipment supplier wants to find a standard curve to meet the requirements of beginners. Through creative practice, the author thinks that this method is unrealistic, at least it does not meet the creative needs of feature films. Because the tone, atmosphere, scene and lighting conditions of feature films vary widely, the pictures tend to be subjective, stylized and formalized. Different from TV series or TV programs, its shooting is mainly carried out on the set, with good lighting conditions and large and uniform illumination; It is also different from news documentaries, and its shooting is mainly based on documentary restoration. In order to meet the requirements of digital film shooting, the gamma curve and related parameter values must be changed at any time.

What is a magnetic transfer adhesive?

The author has some immature opinions on the technological characteristics of magnetic transfer adhesive. At present, the technology and technology of magnetic transfer adhesive have been perfected, and the washing quality and operation experience of local printing and printing plants are closely related to the final copy quality. Everyone has always been concerned about the relationship between pre-shooting and film transfer. What did you shoot in the early stage, and then you can spread the film later? It is the consensus reached by the author and foreign processing plants that the monitor display shall prevail. Last year, the author had an exchange with a system engineer in Alai, Germany. She said that the purpose of developing magnetic transfer correction software for ARRI laser is to accurately transfer the film seen on the monitor. Therefore, this shooting is entirely based on the effect seen by the monitor, rather than thinking too much about what it will look like to convert it into film. Because the film is much wider than CCD, the dynamic range that CCD can collect can be recorded on the film. If the picture is particularly gray and the dynamic range is adjusted very small in the early shooting, it is not appropriate to make full use of the limited dynamic resources of CCD. According to the author's experience, the early shooting should make the picture brighter, the tone harder and the contour correction stronger. In this way, after magnetic transfer, the film will become soft and weak, and the projection effect will be just right.

Because the magnetic transfer glue is recorded on the remake film, the tone is softer, the color is lighter and the basic fog is smaller than that recorded on the film. When we watch the digital movie from HD to film, we think that the dark part is clean, the layering is rich, and the influence of noise is appropriately reduced. Therefore, in this sense, the number of pixels and resolution of digital motherboard, and even the imaging quality of optical lens are particularly important. It is suggested to use high pixel CCD with film fixed focus lens.

Digital images and movie images

Digital movies here refer to digital copies or film copies shot and projected on the big screen of cinemas with digital high-definition cameras, rather than TV movies broadcast by TV stations. Regarding the image quality of digital movies, I think 1920? The resolution of 1080 has fully met the requirements of large-screen projection. At present, the dynamic range and adjustment characteristics of digital camera CCD can fully meet the creative requirements of general feature films. So for ordinary movies with average cost, high-definition shooting should not be a problem. I hope that in the near future, the technical quality and artistic creation level of digital movies will be better than that of 35mm film movies.

Is it necessary to take film as a reference for the future development of digital movies? I don't think so. The original goal was to achieve a cinematic picture style and make digital movies accepted by the film industry, so as to survive. With the continuous progress of technology and the change of ideas, you can make your own unique style of high-definition movies in the future. HD is HD, and film is film. The two can develop in parallel, and there is no question of who will replace who.

This time, we found many advantages of HD shooting from the transferred film copy. For example, the dark part is very good, which may be because the fog is smaller than the negative when recording on the intermediate film (reverse film), and the low-density layer is more transparent and richer than shooting directly on the negative film. Especially for dark shooting, before filming, it was necessary to shoot with 500T and 800T, and the particles would be very large and the contrast would be great. Now shooting in high definition, the layering looks soft and the density is there. Therefore, how to give full play to the advantages of high-definition shooting needs careful consideration.

Film movement

The film is limited by style, and there are not many obvious actions. Although the lifter is used in the shooting, it is only to get a high position, and the speed is reduced as much as possible when shaking, so that the progressive scanning picture is continuous and clear, and the visual effect of the big screen is smooth. The machine did not appear serious tailing phenomenon during shooting. Because the high-definition camera is relatively light, it is much more convenient for photographers to take pictures with the camera stabilizer.

Through the filming of this film, the author believes that in the era of digital movies, we should not only master the characteristics and adjustment of digital cameras, but also strengthen the use of traditional film photography modeling methods. It is unrealistic to think that digital movies can be made only by a set of parameters or a gamma curve provided by equipment suppliers.

Light distribution and lighting control

Because the whole tone is achromatic, the machine parameters are adjusted for achromatic, and the light is mainly scattered, so as to reduce the light ratio as much as possible. In order to cooperate with large aperture photography, low light illumination is basically used. In order to reduce the color temperature contrast at night, we all use high color temperature lamps. The field exposure meter has a sensitivity of 320, a speed of 24 frames, an exposure point reading of F 1.4 ~ 2.0, and a light ratio of 1:3 and 1:4. The adjustment of aperture and parameters depends on the display, and the final modification is through parameter adjustment. In the case of unsatisfactory lighting conditions, parameter adjustment can also play a role, which was unimaginable when shooting with film before. When shooting in high definition, if you feel that the dark part is a little worse, it is too late to diffuse the background light or the scattered light in the evening is not enough, you can adjust the range and amplitude of black level and black gamma to improve it to some extent. At the same time, it is necessary to adjust the gray film, filter and negative gain to obtain the best aperture value and depth of field range, so as to achieve the most suitable tone.

Application of optical lens

It is a difficult problem to get the picture effect of shallow depth of field in the case of focusing. The diagonal of CCD of high-definition digital camera is 2/3 ",and the depth of field is two and a half steps larger than that of film camera under the same aperture. However, the real scene we use is very small, and we often use wide-angle lenses, so the control of depth of field becomes a difficult problem. The whole scene was shot with the maximum aperture, and the aperture was opened to T 1.9 and 2.0. Sometimes move the back focus, adjust the focus ring to infinity, and then move the back focus to find the foreground, so the background is blurred. It is a difficult problem to follow the focus here. In the past, film shooting was considered true as long as the focus scale was within the depth of field; Now shooting high definition, you can also have virtual focus in the depth of field. This problem is said to be caused by CCD contour correction. To this end, we often check the back focus of the lens on the spot and measure the scale with a tape measure. We didn't use a fixed-focus lens this time, but 5.3? 1 1.5 times zoom lens, but shooting with fixed focus lens. We put adhesive tape on the hood barrel, and recorded the conversion values of all fixed-focus lenses on it, and stipulated that only a few fixed focal lengths should be used. Finally, when the screen is displayed, the perspective effect of the screen is better and the connection is smoother.

Adjustment of color temperature and hue

Different from the usual practice of TV camera shooting, we don't use white paper to adjust the white balance of the lens and AWB button, but only use D5600 switch to switch the preset color temperature of the camera between 3200K and 5600K, which is roughly equivalent to the conversion between light film and solar film. The main color of the scene is adjusted by memorizing the parameters of white level, main gamma level and black level with files A and B respectively. The reason is:

(1) The white paper is not suitable for co-production of feature films, but is more suitable for TV programs. Because it is difficult to determine the position and direction of white paper, it is also difficult to repeat; Moreover, film lighting is often mixed light with different color temperatures, and it is often necessary to add colored paper to change the color of the light source; What's more, the tone of a positive film is often subjective and emotional, so it is not necessary to use the same color temperature balance to make different scenes? White balance? .

(2)HDW-F900 has no manual color temperature continuous adjustment function, so it cannot define the basic color temperature. Of course, if you can define a color temperature value, the color will be different. For example, the color temperature is 4300K, which can be green or blue. However, it should be noted that the proportion of white level, black level and main gamma is balanced and cannot be unbalanced. Just like the three curves of film, they can't cross, so the colors from the bright part to the dark part are basically the same, and the deviation is not too big. The high-definition camera can change the color temperature balance value at will, and can also change the white level, black level and gamma value of RGB, so that the picture is biased towards a certain tone. This brings great flexibility to photography creation, making it possible to adjust the tone of the scene on the spot, and it can be repeatedly controlled.

It is also very important to use matrix to change the tone of the film. Before shooting, the director asked the film "Winter Solstice" to adopt a cold gray tone to avoid too many colors. Therefore, the wall color of the main scene is required to be medium gray, but it is green after shooting. After studying under the famous photographer Mr. Chi, this problem was solved by matrix method. (At that time, HDW-F900 had not been upgraded, and the color matrix had no automatic sampling function. )

Modeling treatment of movie pictures

Digital movies can realize movie-like images. To this end, photographers must have a sense of film modeling and master the characteristics of film-feeling pictures, their tones and colors. Only in this way can we make good use of the adjustment characteristics of CCD.

Before shooting, the director repeatedly stressed that although the film is shot in high definition, it must be handled according to the screening effect of the big screen, not like a TV series. To this end, the author watched some reference films before shooting and thought about the problem of picture modeling. Finally, it is established that the film is based on cold gray, using achromatic color as far as possible, and choosing cloudy shooting, the exposure can be slightly less; Using shallow depth of field and specular reflection to enhance the spatial perspective of the scene; Use more medium shots than close-ups; Increase scene scheduling and long shots, and use fewer shots. The following is a detailed introduction.

Contour and detail adjustment

Before that, we turned off the details when shooting the test film and the sample film, and found that the focus of all the shots was soft after reaching the big screen. Therefore, under the condition of large screen projection, if the information content of the image is not enough, it is necessary to enhance the contrast of the details, and the key is how to grasp the scale. In this shooting, we control the detail value between 30 and 75. If you are shooting a panoramic view or a sun scene, turn it up a little; If you take close-ups or night scenes, you should turn it down. Especially in the case of low illumination, we find that noise also increases with the increase of details, which should be paid special attention to. Details can also control the grid climbing phenomenon. For example, we have encountered the phenomenon of grid climbing when shooting bamboo curtains, which can be basically controlled by adjusting the HV and Level dependence values of details.

Adjustment of hue and contrast

By adjusting the parameters such as gamma type, black level, black gamma, main gamma, inflection point and white-cut level, this method customizes a most matching gamma curve for the scene brightness relationship of each shot, so that the brightness interval of the scene can be compressed or expanded to the fully available dynamic range of CCD in a proper proportion. This is essentially a problem of how to reasonably allocate the limited dynamic range resources of CCD. We basically make this adjustment for every shot. Because the composition, scene, lighting conditions, brightness interval and tone relationship of each lens are different, it is necessary to change the photoelectric conversion characteristics of CCD and redistribute the dynamic resources without losing the brightness level of the scene and wasting the dynamic resources of CCD. Moreover, there is still a big gap between the effective dynamic range of CCD and the width of film, so this adjustment is particularly important.