With this Addon you will be able to zoom out even further. Works on base game and all expantions.
I take no credit for this addon. I decided to upload it since Relic forums went offline and I had a hard time looking for it.
First extract the file you downloaded with 7zip/winrar, then move the lua file to W40k\Data folder.
Full 3D-Camera needs to be on in the graphic options, otherwise the mod will not work.
For the complete camera mod files click here.