There are some special areas which take longer time to render and need more samples than the other areas.
In this case, that is the background with heavy DOF and bokehs.
So I rendered the image 2 times
First, 3000 samples, noise threshold 0.03 : took about 10mins to clean the image at 1600px height
Then, use region tools, select the DOF areas, raise render samples to 10000, noise threshold 0.01 : took 10 more minutes to kill all the noise.
Here is the render settings screengrab. Don’t forget to set maxdepth to 16 and light samples to 24 to have better lighting quality.
5. POST PRODUCTION
Lots of post prodcuction works can be done inside Fstorm Tone Mapping
I often play with contrast, glare power and LUT to colorgrading the rendering with strength of 0.3-0.4
After that, I open image in Photoshop and use Camera RAW to enhance contrast, sharpness and colors.
The tricks here is to save rendering in EXR 32bit format and when you open it in Camera RAW, it will automatically be way much better !!! Sometimes it is too much and you need to adjust a little bit of exposure, contrast, hilights.. but normally it doesn’t take me too long. See the result below ( raw on the left and post on the right )