Fits in the center slot with no problem. 

hello ， the AI to EOS adapter ring i ssuitable for nikkon AI Mount lens and canon camera body. so you need to confirm your sigma lens specific mount . We care about our customers, any questions, you can ask us directly at customer@kentfaith.com. All emails would be replied in 24 hours, no exception. 

hello,it can fit sigma contemporary 150 600mm.the compartment inside the backpack is removable, you can DIY according to the size needed. 

You can control camera shake by using your mirror lock, camera shutter release and cable, tripod securely tightened and all legs as squat as possible. The higher the tripod the less stability you have, but you can always attach your camera bag to hang on the hook, located on the bottom of the tripod to act as a center weight. And lastly, if you do not have a camera shutter release cable, the higher your Shutter Speed the more you will be able to control the “camera shake” or blur in your photos. I hope this helps.