Well hopefully the above will be able to convince you, I know you have know reason to trust me, but hopefully the sources above will do the trick. But just know that I without doubt both based on my own experiences, the experiences of others (including active duty pilots, and the documents that I've listed above can confidently say that spotting in DCS is not as good as it should be maybe not necessarily as much in max range, that being said imo it is a bit to low especially for stuff like big jets and contrails, (depending on your graphic settings) but in particular the clarity at which you can see stuff under this max detection range. Maybe this post could be a good read in this regard: https://forum.il2sturmovik.com/topic/54749-spotting/?do=findComment&comment=838363