What CRF or settings I should choose for h265 in order to achieve a similiar quality of h264? I'm doing some experiments with HEVC x265.

I have a raw footage and the quality of details of h264 with same CRF setting looks better than h265.

Shouldn't be the opposite?

Maybe my setup isn't the best: I'm using ffmpeg for transcoding and vlc for review the videos, then i copy the screen content and compare the screens on a program like photoshop.

FFmpeg commands I using are the following:

ffmpeg -i input.mp4 -c:v libx264 -crf 30 -c:a copy output_h264.mkv


and

ffmpeg -i input.mp4 -c:v libx265 -crf 30 -c:a copy output_h265.mkv


I used 30 as CRF for testing purposes because the artifacts are more visible :)

Could the loss of quality be caused by VLC and its experimental support in deconding h265? Maybe something more visible at lower bitrates?
The CRF scales for x264 and x265 do not correspond. x265 CRF 28 is supposed to be equivalent to x264 CRF 23. But x265 is not yet as mature in its development as x264, so take that CRF equivalence with a pinch of salt. 

That said, you can try to establish your own calibration between the current versions of the encoding libraries in your ffmpeg by running the following command, which executes two popular video quality metrics:

ffmpeg -i encoded-video.mp4 -i reference-video.mp4 -lavfi "ssim;[0:v][1:v]psnr" -f null -


The final lines of the console output will contain:

[Parsed_ssim_0 @ 000000000039ad80] SSIM Y:0.984483 U:0.980458 V:0.980921 All:0.983219 (17.751712)
[Parsed_psnr_1 @ 0000000000398320] PSNR y:42.63 u:43.19 v:44.09 average:42.90 min:42.07 max:46.16


So, run the command once with the x264 output and once with x265 and compare with different x265 outputs, till you get similar measures. Of course, these metrics aren't perfect but you can use them as a rough guide to establish equivalence.