Hi there!
I’m currently working on a model which needs to be matched up pretty well to a concept sketch. So here’s the question: How can I make the main model transparent so that I can clearly see the concept underneath?
So far I’ve tried using image planes and activating transparency, but this only makes the subtools transparent, which means that I can only have the main model transparent if I have something else selected.
Any help here?
I tend to work the other way, by this I mean rough out my zsphere chain or mesh first and then use Spotlight to load in my images and set them to a mid transparency. I them hit hotkey Z to allow me to manipulate the mesh behind to match the reference I want to use, I find this quick and very simple to use and negates the need for reference plains.
Hope this helps 
Thanks! A nice tip. I tried it and it works, to some extent. The problem is that the image wont match the model of you scale it. Big problem. Let’s say you’ve matched the image perfectly, then you want to rotate and scale the model. Well, you will have to line it up again.
Any other ways? 
Apply your reference image as a texture to a plane (or the ImagePlaneX model or the reference image cube – they’re both included with ZBrush 4 in the Tool>ImagePlane section of LightBox along with texture templates).
Append this as a subtool to your model that you’ll be sculpting, then activate Transparency and turn Ghost off.