I have a simple model with a metal material that has some procedural noise to give it some realism. These noise irregularities of the material show up nicely in the material preview but not in my final render. I can’t figure out why. I’ve tried adjusting lighting and tweaking things in the compositor but still can’t make the details appear. I think I am missing something about how to work with lighting and cycles and bump maps. I have a basic 3 light setup with an hdri environment. In the Render Properties panel I’ve set the Color Management look to Medium Contrast. Below are two images for comparing. The top brick is where the material detail is lost in the rendered image. A link to download the file is also provided.
The preview image, which is essentially EEVEE is lit by one of Blender’s built in HDRIs, which provides both lighting and something for the surfaces to reflect. Adding an HDRI for Cycles (even just leaving the additional lights in place) gives a more satisfactory result (imho). Turned the Compositor stuff off.
Oops… just noticed that you do have an HDRI, but with its strength set at 0.25. I used an indoor one, which often has more light sources and more interesting stuff going on than one with a fairly uniform sky. Mine was at full strength.
In Material Preview mode you can check Scene Lights and Scene World in the wee drop down to the right of the shading buttons. At least that way you can preview you actual HDRI. Then, if you enable Node Wrangler you can go to your Shader Editor, switch to World instead of Object, select the HDRI, press Ctrl+T to get a Texture Co-ordinate and Mapping node and rotate the HDRI in Z to get the best look you can.
In your case I think the result you are getting is all down to the HDRI selected plus the fact you are running it at less than 1.0 strength. I often light my scenes/objects with nothing but an HDRI and almost always leave the Background Strength alone.
