I've had both. The first one was the old grey style, which was larger in size than the newer green version. It was the AT80 HD version. Real nice, but couldn't tell the differences between them. My newer one is the STS80. If I had to do it all over again I would purchase the ATS65. It is a little smaller, compact, and for backpacking allows the same quality of optics in the larger objective. Also, when viewing animals, and looking towards the sun its allot easier to view thru the angles optics. Your hat will block the sun from getting in your eyes. I was told that the HD's would be better if taking photos thru it. I take them thru my new one and they compare almost exactly to what I took with the older style. If your going to use the optics in a stationary position the the straights will be the answer. Ie looking out your car window or standing and viewing. Later.