Skyline Arch, Juniper.

Here I've shot Skyline Arch in Arches National Park with a foreground

juniper. But the perspective makes the juniper apear larger than the

arch, which is itself massive. Have I committed a great "landscape

sin" by playing with relative sizes this much?

Picture looks wonderful! Brilliant colours that contrast well with each other and great sharpness in the photo. Great piece of work you have here.

The perspective seems off to me.

Shooting with a view camera, you should have been able to fix this with tilt and improve the overall composition.