Maniphest T66167

depth of field not working fully
Closed, Archived
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Assigned To
Philipp Oeser (lichtwerk)
Authored By
grant abbitt (grant.abbitt)
Jun 27 2019, 9:22 AM
Tags
  • BF Blender
Subscribers
Brecht Van Lommel (brecht)
grant abbitt (grant.abbitt)
Philipp Oeser (lichtwerk)
William Reynish (billreynish)
Yevgeny Makarov (jenkm)

Description

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.67

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-26 19:03, hash: rB155c62b070a9
Worked: (optional)

Short description of error
the depth of field doesn't seem to work properly here is a video explaining the fault
https://drive.google.com/open?id=1vpr8nS0feH-mMYD1PyJd6iAMHkFAp3qF
The f-stop is very unnatural and render times go very long when it's down to 0.1.

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]

Event Timeline

grant abbitt (grant.abbitt) created this task.Jun 27 2019, 9:22 AM
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).Jun 27 2019, 11:02 AM

Not 100% sure about this, but real world scale has an important influence on the effect.
Here are 3 files (all with camera f-stop 2.8), but with different object scales / camera distances:

T66167.blend632 KBDownload

T66167_b.blend632 KBDownload

T66167_c.blend632 KBDownload

Framing is the same in all, but DOF effect is different in all of them.

Philipp Oeser (lichtwerk) added a subscriber: Brecht Van Lommel (brecht).Jun 27 2019, 12:19 PM

@Brecht Van Lommel (brecht): Think this corresponds to how this is working in reality? Could this be closed (or are we indeed misbehaving)?

William Reynish (billreynish) added a subscriber: William Reynish (billreynish).EditedJun 27 2019, 1:37 PM

Keep in mind that the DOF depends on the world scale, the sensor size, the focus distance and the distance from the camera.

AFAIK, the DOF size in Blender is correct.

Here is an example of various identical poles placed at different distances (10cm, 30cm, 1m, 2m) with the focus set to 2m. F-stop is 2.8.

As you can see, you get a lot of bokeh blur on the objects that are out of focus. With a real-world 35mm camera, you actually don't get extreme shallow DOF with f2.8, if you photograph objects at a distance To see strong DOF, you'll have to have something closer to the camera to see it more.

Photographers use large sensors, long lenses, large apertures and distance separation to get extreme shallow DOF, if that's what you are after.

William Reynish (billreynish) lowered the priority of this task from 90 to 30.Jun 27 2019, 1:51 PM

Unless you can prove the DOF is wrong, by comparing to an exact match real-world setup, I am marking this as invalid

grant abbitt (grant.abbitt) added a comment.Jun 27 2019, 4:27 PM

<Keep in mind that the DOF depends on the world scale, the sensor size, the focus distance and the distance from the camera.>
and also the focal length of the lens but i cannot get the depth of field to be effected by the lens size.


in this picture i just quickly took on my canon 600d crop sensor. 135mm lens, 3.5 fstop there is a lot of blur in the depth of field. I am about 1.3 meters away from the radiator (subject in focus) and around 3 meters from the blue bed sheet. I cant seem to mimic the same effects in blender

sorry if I have made a mistake I'm just trying to fully understand it. I hope to do a tutorial on this so others can understand it as well. Thanks for your time

Yevgeny Makarov (jenkm) added a subscriber: Yevgeny Makarov (jenkm).Jun 30 2019, 11:01 AM
In T66167#708022, @grant abbitt (grant.abbitt) wrote:

I cant seem to mimic the same effects in blender.

On your screenshot the camera is 18 meters away from the object! On photo "about 1.3 meters".

In my test, the DOF is very close to reality:

grant abbitt (grant.abbitt) added a comment.Jun 30 2019, 11:09 AM

thanks for your time on this and sorry if I have been frustrating I must need to look into cameras further to try and understand what's going on more. Many thanks

Philipp Oeser (lichtwerk) changed the task status from Unknown Status to Unknown Status.Jul 1 2019, 10:51 AM
Philipp Oeser (lichtwerk) claimed this task.

Will archive for the time being then...