Backdrop selection

I believe I can add a third backdrop, and still easily handle the swapping method, so I'll try that. 

I've ordered proper green screen material that will replace the light green fabric.  

The Ivy fabric was also something I had lying around, and might leave it just as a patterned backdrop until I find something else I like better.  Most of my sewing is with solid colors, so it'll have to be something I buy just for this.

As a third, I'll probably put a bit darker solid color from the spare bolts I have.  

I tried using black, and while I like the effect a lot, it messes up the exposure on the laptop, and I can't find any way to adjust that.  The auto exposure seems to be doing area metering, not using face detect or anything, so it sees all the back and ups the exposure, saturating my image.

Backdrop length

While the fabric I'm using is all 56" wide, the height I mounted the pole(81 inches from the floor) means that when the backdrop is all the way down, the lower edge is right at the bottom of the laptop camera frame.  This would have been better if I'd mounted the pole 5" lower, as the top extent of the backdrop is never on camera.

To adjust for this, I might sew on a bit of leader, perhaps a 12inch strip of scrap fabric to the top edge of the backdrop, and attach it to the pole.  This will give plenty of margin to lower it.

Control

It seems like it would be pretty easy to put a color sensor pointed at the front side of the roll, and automate switching colors.  Further, with a simple rotation sensor (such as magnets and hall effect sensor) I could automate the down motion to stop at the correct spot. 

I'd considered making the control wireless, perhaps operating with a keyfob, but I really only want to control it when sitting at my bench, so reaching to the switch isn't an issue, and the wire is run around the back of the bench, so it's not in the way.

I'll use it for a bit to decide if it's worth putting in the extra effort when it's simple to use as-is.