DOF and Phisical camera

[Alexander Petrov]

Micha, Damien pleaseeee help me :-\ Finally i'm finished my last interior, and i want to put some DOF to bring more reality. So i found that when i use phisical camera the Aperture is inactive, and i didnt know how to control the blurryness. The only way to control that is Override Focal Dist. but the effect is unnatural ???

[fpedrogo]

Re: DOF and Phisical camera

Hi
When you are using the physical camera you have to control the DOF through the F-Number. Large value on the F-Number produce less DOF and low value produce more DOF. The problem is that the F-Number also controls the exposure, so you have to control the exposure of you scene using the shutter speed and or the ISO.

Best
Fernando

[Micha_cg]

Re: DOF and Phisical camera

The problem is that the F-Number also controls the exposure, so you have to control the exposure of you scene using the shutter speed and or the ISO.

A simple solution to keep the exposure constant - disable the exposure option of the phys cam.

[Alexander Petrov]

Re: DOF and Phisical camera

The basic problem, is that the DOF is not optical accurate. When i type desired Focal distance, nothing happens ??? I'm working in millimetters viewport, maybe this affects somehow :-\ But when i decrease Focal distance, blur coming into view, but blurs all scene.........there's no focus, there nothing :

[dalomar_cg]

Re: DOF and Phisical camera

I think your F-Stop is probably really low then. Any time you have a very narrow range where objects in focus you've got a very shallow Depth of Field. In practical terms, most lenses have a minimum F-Stop of between 4 and 6.7. Its really only fixed length lenses that really have F-Stops below that, and even then your getting a minimum F-Stop around 3.2. Any lower than that and you're really pushing it in terms of what kind of lens you could shoot with in the real world.

Keep in mind that most people wind up shooting with an F-Stop between 10 and 18.

[bybarra]

Re: DOF and Phisical camera

This is an intresting thread.
I normaly use just the DoF option, override focal dist., and adjust the Aperture untill I get the affect I desire.
I have recently started playing withthe physical camera options. I have found that, for the most part, it's alot like using my new DSLR camera.
My question is, Is there a default focal point when using the Physical Camera? ( like cords 0,0,0 ) I am almost alway rendering jewelery so it's easier to get an accurate focal length. but having an idea as to where to position my piece, when using the Physical Camera, would save a few minuites of setup time.

[Micha_cg]

Re: DOF and Phisical camera

bybarra, look at the tutorial section of the forum, there is a render tool collection thread by me. There you find a tool for easy set the focus point at the scene and showing a plane where the focus go through. It's good time saver for accurate DOF placement, - shoudl be a standard tool.

[Alexander Petrov]

Re: DOF and Phisical camera

Thanks again guys, after my post i was read some literature, and yes fpedrogo is right ;D The only way to control DOF in Phisical camera is F-number option. As the fpedrogo says low values makes DOF very sensitive and produces high blurry efect, and the other way high F-number values produced low blur. My mistake was that i used very high F-number value - 8 and DOF not affected on the scene ;D Now i decreases F-number to 2 and everithing is allright To prevent the scene overexpose as result of low F-number values, i was increase Shutter speed to 2000-3000 also decrease ISO to 200 The result is perfect, and i'm very happy ;D

PS to prevent excessive render time, i was turned-off Cartmul Rom filter, and set Adaptive DMC Sampler with values min-1/ max-100. My test results shows perfect render time/ quality ratios

[govinda_cg]

Re: DOF and Phisical camera

I suggest you to try the z-depth technique to use with photoshop LENS-BLUR filter also. I found it really nice and more accurated to control in realtime my blur effect on rendered images.