VRay Physical Camera Tutorial
If you haven’t used a manual photo camera in real life, this tutorial is for you!
As a photographer, I’ve always found the settings for VRay Physical Camera very natural and self-explanatory.
So it came as a bit of a surprise to find out how many people actually find them frustrating and hard to understand!
So here’s my attempt to simplify it a bit!
This is the first parameter you should pay attention to. It is set in millimeters and works just like changing a lens on a SLR camera.
Low value = large angle of view (Wide Angle lens in photographer lingo) High value = small angle of view (Tele Photo lens).
Just look at this image to see what I’m talking about!
Keep it realistic!
It is scientifically proven that the focal length of a human eye is
45mm so images rendered with this value will look most natural to people. Wide angles will make rooms look larger, objects further away and distorted and stretched out. Tele photo lens (50mm+) will make objects appear closer to viewer and to each other as well as make spaces seem smaller.
SLR cameras use lenses from 6mm to 800, but most of the time it’s more like 16mm to 300mm. The extremely wide or tele lenses can cost as much as a nice used car, so most people don’t have a chance to buy them. This means that 99% of the photos you see everywhere are taken with a lens in 16-300mm range .
That’s why you want to stick to this range in your 3D renderings.
Sure, it might be fun to use very wide lenses, but it distorts the images quite a bit and should be used only when absolutely necessary.
So use your own discretion to choose a value, there are no hard rules here – use what works best for your particular image!
Framing your shot
Ok, so how do you actually frame the shot? I found that the most natural way for me is using the Walkthrough Mode .
So let’s say you’ve set the focal length to 24mm for an interior and now want to find a good shot.
The basic procedure is selecting your camera and pressing C to change your view to Camera. Once you’ve done that, turn on the Safe Frame to see exactly what will be rendered (Shit+F).
Now you are ready to move around – press the Up arrow key on your keyboard to enter the Walkthrough mode and click in the viewport. Now you can use the following controls to move around:
- Up/Down – Move forward/backward
- Left/Right – Move left/right
- Left click + drag – look around
- Middle click + drag – Pan up/down/left/right
If the camera moves too fast or too slow, use the bracket keys [ ] to adjust the walking speed!
It’s very similar to moving around in a video game and after a bit of practice you can get exactly where you want to be.
In real world architectural photographers use tilt/shift lenses or large format cameras with movable backs that rotate, and tilt to get these same results. But I don’t think it’s necessary to explain all that.
For us it’s very simple – 99% of the time all we want from this section is to get straight verticals in our image – just hit the Guess Vert button and be done with it. Vray will set the correct amount of Vertical Shift to
straighten them out!
Horizontal distortion rarely look right, and it’s best to align the camera and target in a straight line manually if you need parallel horizontal lines.
So this is the part that always get’s non-photographers confused.
“How do I make the image brighter? Do I change the Shutter Speed? Film Speed ISO? F/Number?
Which one is the correct way?”
The thing is… there is no CORRECT WAY! You have to use them together to get the correct result!
First let’s understand how the camera works!
Shutter speed controls how long the film or sensor is exposed to the light.
Long exposure means more light and brighter image, it also may cause fast moving objects to appear blurry – that’s Motion Blur .
Shutter speed is usually set in fractions of a second 1/200, 1/100, 1/30, etc. (in Vray Physical Camera the “1/” part is set by default so if you set the shutter speed to 50 it’s actually set to 1/50th of a second).
F/Number (Aperture) sets the diameter of the hole in the lens that let’s the light in. Larger opening let’s in more light and makes the image brighter, as well as increasing the DOF effect.
These numbers work in reverse so increasing the aperture value actually decreases the size of the hole! This means that f2 is brighter than f8 and f8 is brighter than f16 (you get the point!).
ISO just controls the sensitivity of the film/sensor. Higher sensitivity means brighter image, lower means darker image.
VRay artists are actually very lucky compared to real photographers – in real world increasing the ISO means increasing the image noise, so it’s limited in it’s use. For us however it doesn’t have this drawback!
You can increase (or decrase) this value as much as you want without any negative effects!
ISO is the most flexible way to adjust the exposure – it doesn’t affect anything else except the brightness of your render!
“Ok, but how do I set the exposure for my render?!”
Here’s a how you should do it – First decide if you will use camera DOF and Motion Blur (many people choose to add them only in post-production).
Adjust the F/Number to get the desired amount of DOF, adjust the Shutter Speed to get the desired amount of Motion Blur and finally use the ISO to get the desired Exposure of the image.
If you don’t want to use VRay DOF and Motion Blur – you can use any of these 3 parameters to get your desired exposure, it doesn’t matter and nobody cares which one you use! The result is still the same!
This parameter allows you to control the darkening of corners. I usually leave it at 1.0 and decrease only if I need very even light in the image. I think it helps to draw the viewer in and makes the image a bit more interesting.
Since it’s a natural phenomena that is present in real photos, I think it also makes the renders more realistic.
You can also turn it off by setting it to 0 and add vignetting in Post.
Since all lights have a slightly different color, you can use this parameter to adjust the overall color tint of your render.
My advice is to set it to Neutral and forget about it – this way you can start without any color cast and mess with the colors later in Photoshop.Source: viscorbel.com