Viewport "Focal Length" doesn't match Camera's focal length #78320

New Issue

Adam · 2020-06-26T17:24:03+02:00

Adam commented

2020-06-26 17:24:03 +02:00

I've noticed that camera's focal length and viewport's focal lengths don't match. I agree with the Alessandro Padovani (padone) who created the parent task.

Basically, when you have a scene and want to do a quick test render of what you see in the viewport you need to set the camera's position/rotation to viewport's view. To do that you first view the scene using the viewport then set the camera's position/rotation using Ctrl+Alt+0 (numpad) and hit F12. The problem with this is viewport's focal length and camera's focal length don't match even though they are both set to 50mm.
When you hit Ctrl+Alt+0, camera's position/rotation is set but what camera sees is actually zoomed in which seems like 100mm. So, if you want the camera to see what the viewport sees then you need to change viewport focal length to twice of what camera is.

I don't know what the parent task was closed.

I'm using Blender 2.90
Build date: 2020-06-23

I've noticed that camera's focal length and viewport's focal lengths don't match. I agree with the Alessandro Padovani (padone) who created the parent task. Basically, when you have a scene and want to do a quick test render of what you see in the viewport you need to set the camera's position/rotation to viewport's view. To do that you first view the scene using the viewport then set the camera's position/rotation using Ctrl+Alt+0 (numpad) and hit F12. The problem with this is viewport's focal length and camera's focal length don't match even though they are both set to 50mm. When you hit Ctrl+Alt+0, camera's position/rotation is set but what camera sees is actually zoomed in which seems like 100mm. So, if you want the camera to see what the viewport sees then you need to change viewport focal length to twice of what camera is. I don't know what the parent task was closed. I'm using Blender 2.90 Build date: 2020-06-23

Bastien Montagne was assigned by Adam

2020-06-26 17:24:03 +02:00

Adam commented

2020-06-26 17:24:03 +02:00

Added subscribers: @50p, @ideasman42, @mont29, @padone

Bastien Montagne removed their assignment 2020-06-26 17:31:12 +02:00

Richard Antalik commented

2020-06-29 19:41:23 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-06-29 19:41:23 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Richard Antalik commented

2020-06-29 19:41:23 +02:00

Are these steps applicable?

Press {key 0} to switch to camera view
Press {key Home} to maximize camera area so it matches viewport closely
Align view with object
Press {key Ctrl Alt 0}
Camera is placed closer to object as viewport camera was.

Are these steps applicable? - Press {key 0} to switch to camera view - Press {key Home} to maximize camera area so it matches viewport closely - Align view with object - Press {key Ctrl Alt 0} Camera is placed closer to object as viewport camera was.

Germano Cavalcante commented

2020-06-29 19:56:06 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-06-29 19:56:06 +02:00

I don't really understand the concept of Focal Length in OpenGL
https://en.wikipedia.org/wiki/Focal_length

It seems that this is related to the focus of the image and not the matrix or edges of the projection.

I also tested using the same settings for clip start and cilp end and apparently the origin point is in the expected position:

Perhaps the edges of the camera have to match the smallest side idk

I don't really understand the concept of Focal Length in OpenGL https://en.wikipedia.org/wiki/Focal_length It seems that this is related to the focus of the image and not the matrix or edges of the projection. I also tested using the same settings for clip start and cilp end and apparently the origin point is in the expected position: ![ctrl-alt-0.gif](https://archive.blender.org/developer/F8654002/ctrl-alt-0.gif) Perhaps the edges of the camera have to match the smallest side idk

Richard Antalik commented

2020-06-30 21:29:51 +02:00

Not sure how this is applicable to openGL but in context of cameras this is really just field of view. I think this report is not titled correctly. It may look like this is FL issue while it is camera placement issue. Steps I wrote down are destilled from last post in #43039.

Still not sure if this would be a bug, but it does look like a bug.

Not sure how this is applicable to openGL but in context of cameras this is really just field of view. I think this report is not titled correctly. It may look like this is FL issue while it is camera placement issue. Steps I wrote down are destilled from last post in #43039. Still not sure if this would be a bug, but it does look like a bug.

Germano Cavalcante commented

2020-06-30 22:54:30 +02:00

This change causes the projection matrix of the camera and the viewport to have the same field of view:

diff --git a/source/blender/blenkernel/BKE_camera.h b/source/blender/blenkernel/BKE_camera.h
index 812f5d520d7..2bcb055acec 100644
--- a/source/blender/blenkernel/BKE_camera.h
+++ b/source/blender/blenkernel/BKE_camera.h
@@ -88,7 +88,7 @@ typedef struct CameraParams {
 
 /* values for CameraParams.zoom, need to be taken into account for some operations */
 #define CAMERA_PARAM_ZOOM_INIT_CAMOB 1.0f
-#define CAMERA_PARAM_ZOOM_INIT_PERSP 2.0f
+#define CAMERA_PARAM_ZOOM_INIT_PERSP 1.0f
 
 void BKE_camera_params_init(CameraParams *params);
 void BKE_camera_params_from_object(CameraParams *params, const struct Object *camera);

It would also be necessary to change other default values such as the viewport depth of field and perhaps the initial camera's bounds.

This change causes the projection matrix of the camera and the viewport to have the same field of view: ``` diff --git a/source/blender/blenkernel/BKE_camera.h b/source/blender/blenkernel/BKE_camera.h index 812f5d520d7..2bcb055acec 100644 --- a/source/blender/blenkernel/BKE_camera.h +++ b/source/blender/blenkernel/BKE_camera.h @@ -88,7 +88,7 @@ typedef struct CameraParams { /* values for CameraParams.zoom, need to be taken into account for some operations */ #define CAMERA_PARAM_ZOOM_INIT_CAMOB 1.0f -#define CAMERA_PARAM_ZOOM_INIT_PERSP 2.0f +#define CAMERA_PARAM_ZOOM_INIT_PERSP 1.0f void BKE_camera_params_init(CameraParams *params); void BKE_camera_params_from_object(CameraParams *params, const struct Object *camera); ``` It would also be necessary to change other default values such as the viewport depth of field and perhaps the initial camera's bounds.

Richard Antalik commented

2020-07-02 00:18:06 +02:00

That seems to resolve issue I outlined, so I would send that for review regardless. Still I would wait for response if this is actually issue originally reported maybe.

Germano Cavalcante commented

2020-07-14 14:55:16 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Philipp Oeser commented

2020-11-20 11:42:40 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-11-20 11:42:40 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2020-11-20 11:42:40 +01:00

I'd say there is not much to add from the perspective of the triaging team, now the developer module needs to decide on how to proceed?

Philipp Oeser removed the

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Viewport "Focal Length" doesn't match Camera's focal length #78320