Not much Bokeh effect and weak DOF

[sailor]

Hi,

I enabled DOF, custom Bokeh, and have a camera setting as following,
    focal length : 105mm
    ISO : 25
    F-stop : 1.0
    shutter speed : 1000

The system units is set to mm. The camera is targeting at one of those tables at center. I see some DOF effect close to camera and further down but not much Bokeh effect at all.

Is it supposed to be like that or am I doing something wrong? Please help.

[Beanzvision]

Is your scene to scale?

[sailor]

Yes, scale is correct.

[sailor]

BTW, the image is from IR and I run it for a couple of mins.

[romullus]

A. what is target distance? B. did you change film width/sensor size and/or zoom factor?

[sailor]

The target distance is 43305.371mm and I tried both the target and an object target of the center table. They were pretty much  same.

I didn't change film width(36mm) and zoom factor(1.0) but did change the focal length to 105mm. The Exposure is set to "Use photographic(ISO).

[romullus]

If we enter 105mm, F-1.0 and 4330 cm into online DOF calculator, we get DOF size of 1032 cm. That means 10,3 meters of "razor sharp" DOF. I think that perfectly correlates to what we see in your render, isn't? :]

[sailor]

Yeah, the 10,3 meters of "razor sharp" DOF sounds right, romullus. How did you get that DOF size of 1032cm? Do I still need to move the camera further away from the table to get Bokeh effect? or the subject in this scene is too big for Bokeh effect?

[twcg]

you could increase the sensor-size to simulate a medium-format (~45-90mm) or large-format camera, wich should give you a more shallow DOF with the same FOV and f-stop... you have to increase the focal-length to get the same FOV with a bigger sensor size. that would be the photographic approach...

or you could just lower the f-stop value :)

[romullus]

Yeah, the 10,3 meters of "razor sharp" DOF sounds right, romullus. How did you get that DOF size of 1032cm? Do I still need to move the camera further away from the table to get Bokeh effect? or the subject in this scene is too big for Bokeh effect?

As i already mentioned, i entered your camera parameters into DOF calculator (link is in my previous post) and got the result.

I'm not sure what exactly do you mean by bokeh effect and i have no clue what table you're talking about, but asuming that you want to get more shallow depth of field, i.e. more blurry foreground and background, you have several options. 1. further open aperture (decrease F-stop value), although 1.0 is already unrealistic - AFAIK there's no camera in the world that would have F1.0 aperture at 105mm focal length. 2. increase sensor size - that would give identical output as in step 1, but would be physically plausible :] 3. decrease target distance, but that would bring building out of focus - probably that's not what you would want. 4. choose lower focal length  - that would require to bring camera closer and would change image composition. If you don't want to change composition, and don't care much about physical correctness of the DOF, then i suggest to stick to step 1 and decrease F-stop value even more. Be aware, that this may make your scene look like miniature world :]

[maru]

If you want to force (unrealistic) DOF, then the easiest way is increasing sensor size - that's basically a multiplier for your DOF effect.
If you want to see how DOF really looks, you should allow more passes to be rendered. Reduce GIvsAA in the Performance tab to 2 to make it render faster.

[sailor]

Thank you guys for your advice. Yes, I'm aiming for shallower DOF with bokeh effect and sorry, romullus, what I meant by table is that there is a table under the sun shade umbrella at the center of the image, left side of the woman, and I put the focus right there.

I was trying to find realistic camera setting for DOF bokeh effect but it is already impossible to do so since I can't change camera angle and composition. I did some research on sensor size and got reasonable result with increased value. Also, I tried lower value of F-stop and got similar result but have to decrease light intensity, will play around with those values a bit more.

I have GI Primary solver : Path Tracing and Secondary : UHD Cache in the setting. Do you guys think those would be ideal for this kind of scene and DOF?

[Frood]

Also, I tried lower value of F-stop and got similar result but have to decrease light intensity,

Compensating exposure with shutter speed or ISO value would save you from doing so. And if you change from photographic (ISO) to "use simple", the basic exposure setting is not affected by F-stop/shutter any more and you can tweak both, dof (f-stop) and motion blur (shutter speed) seperately.


Good Luck