I'm using Cycles and finding that the image I see in the 3D Viewport (when using rendered shading) is far crisper than the final render produced with Render Image (F12). I can't work out why.

First, the render as seen in the 3D Viewport (you can see the 3D Cursor) etc.:

3D viewport render

And now the dramatically blurrier Render Image result:

render image result

I'm guessing this bluriness is somehow supposed to be truer? I.e. the crispness seen in the 3D Viewport is a result of not being such a true renderer, i.e. various short cuts (in addition to fewer passes) are at play here. Other differences, I can see are e.g. that the final render includes a definite shadow (that for some reason is not visible in the 3D Viewport view).

I've looked at the Compositor and Shader nodes and I see no obvious reason for the bluriness.

This sphere has been added into an environment created by tracking. I.e. I shot the background footage, solved for the camera motion and then let Blender set up the tracking scene which resulted in a cube (which I replace with a reflective sphere), a shadow-catchter plane and the following Compositor nodes:

Compositor nodes

And then I added my own HDRI (which you see reflected in the sphere) with the following Shader nodes:

Shader nodes

The .hdr file, the .blend file and the background .mkv can be found here:

Any insight into what's going on here would be much appreciated.


You have motion blur enabled. This, understandably, makes the render blurry. Because motion blur can dramatically increase render times, it is not calculated for a rendered preview.

  • $\begingroup$ Super - I really appreciate people taking the time to answer questions that must seem painfully obvious to them but are completely non-obvious to people like me who are just trying things for the first time. I looked for issues with the nodes etc. and it never occurred to me that it might be a desirable effect, enabled to make things look better when movement is involved. $\endgroup$ Nov 24 '21 at 21:04
  • $\begingroup$ @GeorgeHawkins No problem-- I hope I didn't sound like I was talking down. I know that it's often nice just to get another set of eyes on a problem. In general, render/preview disagreement isn't going to be from mats, but from object visibility, render settings, subdivision settings, or particle settings. There may be an exception here and there; it's kind of a shame that there's no "make it like preview" button. $\endgroup$
    – Nathan
    Nov 24 '21 at 21:23

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