<p>Thank you to everyone who replied to this question. I did another test today and found out that at the long end of my 18-300 lens, the magnification is approximately what it should be. I am assuming that to be the case, as I was not able to get a good, measurable image far enough away to use infinity focus, but close to it. I'm sure if I had, the magnification would have been equal to my other 300mm zoom lens (Sigma 70-300). I have to admit I was skeptical of the lens, especially due to the fact that at a close focus there was such a huge loss of magnification. Now that I know about the "lens breathing" issue, i will forever remember to consider this when choosing which lens to use for a certain shot. Again, thank you for the great information and to Shun Cheung for going the extra mile with a photo comparision/illustration.<br>
DG </p>