Something to avoid when digiscoping in dim light is the temptation to increase the ISO sensitivity setting to obtain a faster shutter speed at the expense of increased image graininess. Other times the over-ride/under-ride (+/-) exposure function is used to make the image brighter on the LCD viewfinder-making composition easier. Using the over-ride/under-ride can be very useful, but I'd recommend doing so into the minus rather than the positive. This will give you a faster shutter speed, which helps to freeze movement and improve image sharpness.
Note that I under-rode -0.7 and I have a shutter speed of 1/125th of a second. In all cases the original images were considerably darker. I intentionally under-ride in dim light because I know I have a little flexibility post-processing the image in Adobe Photoshop by increasing the brightness levels. This technique concedes the poor lighting, but opts for the faster shutter speed to freeze movement. I can guarantee this method will improve sharpness in your digiscoped images in poor lighting.
Article and Hermit Thrush photo contributed by Mike McDowell, an avid digiscoper, amateur naturalist, and Eagle Optics employee. Visit Mike's Birding and Digiscoping Blog.