I took my Opteka 650-1300mm zoom to Monroe’s Louisiana Purchase Gardens and Zoo on my birthday and was very pleased with the results on my Lumix GX8. With the ‘no lens’ setting turned on the camera will operate well with the lens. Focusing is manual but automatic exposure is possible and the lens did really well in my opinion. The Bald Eagle photo was processed in Photoplus X7 with Topaz Adjust 5 and reduced in resolution for the web.
A long telephoto lens takes a bit of getting used to, this one is no exception but they are great for isolating your subject with their narrow band of focus. The band of focus with a lens of this focal length is narrow and you need to make fine adjustment, but you can melt away the cage bars at the zoo with one. Be sure to use a support, a sturdy tripod seems best and a high shutter speed to avoid ‘camera shake’ or ‘jitter’.