Book 1 Camera Settings:
f-number – 8, shutter speed – 35, film ISO –800.
Book 2 Camera Settings:
f-number – 6, shutter speed – 30, film ISO –900.
You may be surprised to find that the camera settings found when you select the VrayPhysicalCamera tag, can affect the lighting properties as well as the look and feel of a scene. Most people who aren´t professional photographers don´t realize just how much the camera can affect the lighting and other parameters of your images. I´ll explain a few below that will hopefully provide a basic understanding of what effect each will have on your scene.
Lowering the f-number or f-stop value will make the image brighter. This is because by opening the camera aperture more light is absorbed. In reverse, increasing the f-stop will cause the image to be darker, since you are closing down the aperture. Accordingly this parameter also controls the DOF in a scene. One thing that most newcomers have trouble with is to remember that a big aperture is actually referring to a smaller number. And a small aperture is referring to a larger number. For example a large aperture might be f/1.4, f/2, f/2.8, etc. And a small aperture might be f/22, f/16, f/11, f/10, etc.
In order to show you how the camera settings can make a difference in the amount of light we will take the same scene, a book, and have just a bit of difference in the camera settings. You will see that even small difference in the settings can make quite a difference in the amount of light in a render.
The shutter speed controls exposure time. The smaller the shutter speed value, the brighter the image will be. Conversely, the higher the shutter speed value, the darker the image will be. This parameter also affects the Motion blur effect in your scenes. You must also consider your shutter speed in relationship to your f-stop or aperture setting. They do affect each other as well. The lower your shutter speed, the lower number your f-stop should be. Aperture + Shutter Speed = Exposure.
The film speed or ISO value also controls the brightness of an image. If the film speed (ISO) is high (which causes it to be more sensitive to light), the less light is needed. Higher ISO values are traditionally used for night shot images or fast action shots. With a real camera using higher ISO settings usally results in visually noisier photos. The same problem doesn't exist with using higher ISO settings in Vray. In the 2 book images you can see that just the camera settings alone can affect the lighting in an image without adjusting the light.
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Book 1 Camera Settings: |
Book 2 Camera Settings: |
You can also adjust the white balance from within your camera settings. While a real physical digital camera usually does this automatically (in auto white balance mode), you have the control to change how your image renders in hue by adjusting the white balance. Let´s say you have an image that renders out with a cool bluish cast that you find to be undesirable. By using a color picker to choose the blue hue and adding that color in your white balance setting of the camera, you can adjust that hue to be a more warm color which suits your scene such as in the image below.
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White balance can be controlled |
Vignetting is a term photographers use to describe an image that is missing its edges. A typical vignette in an image would show up as a bright center falling off to darker edges. By reducing the focal length of your camera and turning on the vignetting option in your camera settings you can achieve this effect with Vray.
Another aspect of your camera settings is adding DOF. (Depth of Field) This option is controlled by the opening and closing of your aperture which is more commonly called the f-stop number, along with the number and shape of the blades comprising the aperture.
To have the DOF effect you need to check the Depth-of-field box under the Sampling tab . The Bokeh Effects, found under the Bokeh Effects tab, are also part of the DOF settings. Bokeh is a Japanese word that has been adopted as the term for "out of focus blur quality" of a camera lens or "blurring". Bokeh is now being used in the film, photography and computer graphics industries to describe out-of-focus blurry characteristics. It is determined mainly by the shape of the camera lens and can be seen best on out-of-focus highlights which assume the shape of the lens aperture. A lens with few aperture blades tends to produce angular highlights, whereas a lens with more aperture blades tends to produce rounder highlights. Depending upon the depth of field chosen by your lens focal length and aperture, the details behind and in front of the subject will be out of focus to some degree after selecting your target. While CINEMA 4D´s DOF is a post effect, Vray´s depth of field is actually rendered in real time into the scene during the render. Due to that, Vray´s DOF is evident in looking through a window glass whereas CINEMA 4D´s DOF cannot do this due to the fact of it being a post render effect. See the two images for comparison.
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AR Module DOF |
VRay DOF |
Both were rendered with DOF with the camera looking through the glass panes of a window. In the Vray render the DOF is evident on the outside objects while the CINEMA 4D render shows no DOF on those items while looking through the window glass.
The effect is strongly seen when the camera is very close to an object, such as when you are doing a macro, or extremely close-up photo. So to have a strong DOF effect, the camera aperture has to be open, ie. a small f-number (f-stop) value. That would lead to a very bright image, so to preserve the same brightness over the entire image, the shutter speed needs to be quick. And last but not at least, the focus distance will determine which part of the area will be actually in focus. To get the focus near, you would need a small value and a reverse or higher value for distance focus.