08/12/2010

Vray physical camera set up

The Vray physical camera differs from the 3ds Max standard camera in that it has adjustable settings for ISO, shutter speed and f-stop. These settings can aid in the lighting and overall look of the scene. At first, the Vray Physical Camera settings can appear daunting as there are many settings you can tweak but for the average user who is not an expert in photography, impressive results by changing the following settings can be seen.

Film gate and focal length

It really depends on where your camera is placed within the scene, and what you wish to have in view. You may find yourself restricted by walls and other objects, but you can easily overcome this using camera clipping or setting the object that is causing the obstruction to not be visible to the camera in the object properties. As a base point I would set your focal length to 45mm and your film gate anywhere between 40mm and 60mm.

If your goal is to replicate a real camera then you can find out the specification by doing some internet searching. You will find information on all the settings within the Vray physical camera. I recommend following this guide which goes through the necessary settings and functions of a Canon PowerShot, You can easily adapt this work flow to any real camera.

Shutter speed

Determines the length of time the camera catches the light, the slower the shutter speed, the brighter the image. Motion blur can also be affected by this because a short shutter produces less blur due to a smaller length of time being captured. For interior visualisation a good starting speed is 60 and depending on your intentions with the f-stop you may have to use a slower shutter speed.

F-stop

This controls the size of the camera aperture (the hole that lets the light pass through). A smaller number means a larger hole which will make the object closest to the camera sharper and the background blurred. This is a powerful effect when setting up close up shots and at the same time making other objects appear out of focus which is called depth of field (DOF). By decreasing the f-stop you are brightening the image and you may experience over brightness or a burnt out image. To compensate for this the shutter speed will need to be shortened.

A good f-stop number to start at when focusing on an object closest to you is 2 or 2.8. I use the standard f-number series when choosing the f-stop as these values are exactly twice or one-half the amount of light of the neighbouring f-number. More information on the f-number series can be found here.

For standard camera views without DOF, change the F-stop to 4 or 8 depending on the lighting within your scene. When changing the f-stop, you either double or halve the amount of light that passes through, therefore you need to either double or halve the shutter speed to keep your scene from being under or over exposed.

All other settings can remain their default values. You would only adjust the ISO value if a desired DOF effect has resulted in an under or over exposed image. The only way to control exposure is with the ISO as this has no effect on DOF whereas F-stop and shutter speed do.

If you have any questions about this post feel free to leave a comment and I will do my best to answer as soon as possible.

41 Comments

  1. I’m not usually use vray physical camera,just because it’s so difficult to control.

    When I use vray physicial camera, how do I to control vray sun and vray physical camera?

    Thanks…

  2. jpcutler85 on said:

    Steven,

    When using Vray sun and Vray camera, I tend to leave the Vray sun parameters as default. Then adjust the camera exposure to match depending on it being an interior or exterior view.

  3. siavash on said:

    I found fstop : 4.5 , shutter sp : 100 , iso :100 more close to real world according to illumination of vraylight (mesh) with 40 w and color temp 3300
    but my question is : is this way correct to get to logical settings for camera

    • Siavash,

      If you are rendering still images and not setting up the camera for animation, also not using DOF in your scene you can set the shutter speed and ISO to 100 and adjust the f-stop until you are happy with the general illumination.

      Shutter speed and ISO do not effect your scene in anyway, it only adds another equation to the light intensity. There’s no need to enter various values.

      If you are trying to match a specific camera then that is a different matter, but generally there is no correct way to set up the Vray physical camera only advised settings.

      Hope that helps

      • siavash on said:

        tnx cutler you are right.im really interest to see what a design is going to be in real world before starting any project that’s why in case of camera i try to get to human eye but there are so many factors like materials and illumination that make it really difficult . i realized with cg you can get 90 percent close to a real finished design and your client gets the concepts but for example you can’t have the certain visible color bleeding on a surface , please tell me im wrong and there is a way to do that :)

  4. Hello Cutler, it is all so interesting, its years that I wanted to learn how to render well but time and energies where never enough. so finally I am in, thanks for your posts.
    first little question relating to this topic.
    How do you desaturate GI?

    • Hi,

      In Rhino go to the Vray render options. Under indirect illumination there is a setting for post processing saturation. Set this to a lower value such as 0.7 or 0.8.

  5. halo, i used v ray phisical camera for an interior work , but the image i got is a little blured . Pleas send me some settings to remove the blurnes..

    • Hi,

      The Vray camera will not be blurred unless you have added depth of field (DOF).

      You image could also appear blurred depending on the anti-aliasing filter you have used. Saving out as compressed file formats will also cause the image to look less defined.

  6. Hi.

    IM working with SU-Vray, im doing an interior animation, and i seeme to get the animation very bright, the still pic’s turns out well, and i have tryed several adjustments for the animation, in the framebuffer it all looks fine, but when i look at the rendered frame it looks too bright, i have worked with shutterspeed and the iso, also changed to diffrent cameras, but it still gets too bright, even the material becomes whiter, have you any tips where i should move on to get this better.

  7. Hi James.

    Gamma was the the missing link i had to adjust, now it seemes to get better. It’s harder with animation than still pictures , since you don’t see the final result til you have rendered one frame, i tought in the begining that what you saw in the framebuffer was the result!!
    Im new with vray so im learning, thanks a lot for the tip, it was very helpful.

    Markus

  8. “but if you wish to reverse the effect and make the background sharper and the objects closest to you blurred, increase the f-stop.” ..this is an incorrect information. Bokeh(blured image) can be achieved only with low values of fstop, backround or closest, depends where you focus!

  9. Hey ! thnx for the info !

    But … i dont know what my problem is.

    I use typical standard settings with a few tweaks.. when i render.. the photon/light cache looks great ! but then it goes on with the pre passes…

    It gets darker and darker and the final image is almost black !

    help!

    • The light cache is an approximation so it may well be brighter than the final result. Same with the irradiance map as these are both biased methods, there is likely to be some difference in light intensity. The final result is a mixture of the two. Are you using a Gamma 2.2 workflow? What are your settings and camera exposure settings?

  10. Hi
    If I increase Film Gate to about 80, Focal Length 40 and my V. Sun Parameters are Default, I get my object darker. How to Solve the problem Please Teach me.

    Kamol

    • To increase or decrease the exposure you must do so by adjusting the shutter speed, f-stop and ISO. The final values are determined from the time of day and the environment and the surroundings.

      • kamoldip on said:

        Hi
        May be I could not understand you my problem.
        I could fix the problem. That was the Zoom factor. Now I work as I wanted.

  11. What about the system units? If I’m working with centimeters/system and display units I need to change the default values of focal length and film gate – 36/40 to 3.6 and 4.0 right? Does that means that I should change f-number too?

    • Both system units and whether the model is to scale affect the camera settings. Unfortunately there is no “one click” conversion or lock exposure option. But it has been requested.

      • TONK on said:

        No I’m not talking about a “one click” conversion. Every scene has different lighting and requires different camera settings.
        …I figured it out. The focal length and film gate are meant to be in mm, so if your system units are cm you need to change the values 35mm focal length should be set to 3.5 cm and if you have for example film gate that is 40 it should be 4.0 cm. The other values – are not directly dependent on system units their are related to the focal length and film gate but not the system units.

  12. thanos on said:

    Hello, I dont know if this is the proper place to ask, but i have this issue with my velocity pass. In the max value parameter which is by default 1.0 what should i have? If i add the max velocity that i have on my scene, the motion blur pass is just too weak when i composite it. If i add a low number like 10 or 20, motion pass seems descent. If i leave it at its default value 1.0, the motion blur is just too much and everywhere. So does this max value represents shutterspeed in a way? thank u

    • The max velocity parameter represents the maximum distance in pixels an object travels. A value of 1.0 means maximum velocity for everything that moves only 1 pixel in a single frame. So you will need to identify the object that travels the furthest within a single frame. If that objects travels say 30 pixels, then that is your max velocity. The camera shutter speed has no effect on this method as all calculations are completed in screen space, not 3D space. If you require physically accurate motion blur you should enable it in the V-Ray physical camera and control it via the shutter speed.

  13. sameer on said:

    I am trying to render my scence with f no = 4, sh speed =60, film speed = 100 but render scene is too much dark and very veered contrast, please guide me if any other setting require to make for correct render scene.

  14. dhaval on said:

    i used vrayphysical camera but i dnt get result which i expected.. der iz jus minor changes in still images.. nothing more i hve gt from physical camera is der any additional settings for physclcamera??

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