I recently discovered butterflies and dragonflies and took out my 105 lens which is perfect for this. I was having trouble getting close to my subjects and decided to put the 1.4 TC that I use for my 300 mm for birds and got what I thought were pretty decent shots. Then I got online to begin researching possibly getting a 2x TC for my 105 and found that all of the TC's are supposed to be incompatible with this lens. I've used it twice and the lens has worked flawlessly. What are the issues; will I damage my D7100, or the TC, or the lens?