For quite a while I didn't have problems using my 350D over 5m USB extension leads, and I thought it went away when I started powering the 350D from my SLA, but on the weekend just gone at astro camp the problem reared it's ugly head big time.
I ended up borrowing a USB 1 5m cable with reapeater from someone else at the camp, solved my problem.
I'm now going to take drastic action:
- ditch the 5m cables i have except for one
- put a 4 port hub at the scope, with the one remaining 5m cord to the laptop
- use a powered hub
- build a 12v - 5v box and power the hub from the SLA.
My understanding is that a powered hub is as good or better than an unpowered repeater so should be good.
Now I just need to find the coolest looking USB hub to match the style and class of the GM8
So in summary, I would recommend not using 5m unpowered/un-repeated SUB cables for DSLR's. Seem fine for webcam, RS232, etc.
Roger.