In this case, I wanted to crop out the bush in framing ( not in 'cropping after shot' ) but the terrain made it difficult. If I remember correctly, there was a big dip on the ground at where I wanted to place camera for 50. But I agree, the perspective of 50 is my fav and probably prefer to longer lens on this shot.

Maybe I don't see a point, but You may always move little forward with 50mm or move a little back with 100mm. The framing would be almost the same, little perspective changes wouldn't have been most important here. If I were there, I would have chosen then same 50mm because Macro lens have a little different DOF. It is hard to replace 100mm with 50mm or 25mm with 85mm (where difference is more than about 3:2 focal length), but I like most view of angle here.

I agree. This was the day I wished I had 85 planar. 100 was too long, 50 was tiny tad too short. I wanted to have only one bush on one side.

Well spotted place for the photo. It almost asking for a vertical (portrait oriented image) maybe with a longer FL lens eliminating the bushes from side (just the tree and the rocks).

Thank you very much. I believe I used CP Filter on this.