Why do most or all spinning adapters have the lens mount at the top & not the bottom?
 

I'm going to build my own adapter and would hate to make mistakes that others have already discovered. That being said, I have a question about the design of spinning-cd adapters.

I have a rectangular project box from Radio Shack and it seems to me that I should line up the camera so it mounts at the bottom of the box. In other words, when I sit the camera on a flat surface, the adapter box that holds the spinning ground glass will sit flat on the table as well.

This doesn't seem to be the norm. It seems like all the other spinning CD project box adapters have the camera attached at the top of the box, so there's a lot of the box hanging below the base of the camera. This kind of setup would prohibit sitting the camera down on a flat surface while the adapter box is attached. There must be some reason that people do this. What am I missing?

This is a pic of what I'm talking about:
http://www.makezine.com/blog/257902106_43c89d7477.jpg

All I can figure is that devices like the RedRock are made that way for their rail system and, therefore, other people do the same.

For one, having it on the top looks bulky and weird. Also, having it on the bottom allows for easier attachment to a rails support system.

It's mostly visual aesthetics, but I can't imagine having the bulk of an adapter sticking up from your camera would benefit you other than to have the ability to set it down evenly on a flat surface. Also, who knows what kind of strain you're putting on your camera threads by precariously balancing all that weight above the lens instead of hanging it below.

The main reason I didn't invest in a spinning adapter is because I couldn't stand the boxy, unmanageable shape of the thing. Good luck with whatever you figure out.

Having gone through a design process with my own homemade spinning adapter, it is a simple matter of the logistics of mounting to the base on which camera is mounted, whether it be rails or a solid mount. Nothing else really makes sense, with the necessity of an oblong box.

Ben I have to agree with you man, you'll never make one of these puppies look sleek, however good the picture.

With all the manufactures out there getting closer to each other in terms of picture, it will soon start coming down to how they look.

Another reason is to keep with standards. If you have rods support, the rods centre should be 85mm up to lens centre to remain compatible with matte boxes for example, so this naturally places the lens in the upper half of the box.

Second, the compatability with matte box etc..

Also lens closer to ground retains close to ground ability. You can always hold it high. But if the lens is high you cannot get as close to the ground unless you dig a hole or use mirrors.

Hand-held, the lens low designs seem more stable.