I've now spent a number of hours under the night sky with these two binoculars, and I thought I could provide a good comparison of performance. My 820 is the newest updated version with the orange lettering. It is quite different looking from the original model 820. Also, my 820 is not the ED model, so we don't have to give any allowance for a more expensive glass formula. For reference, I also used my Swarovski 7x42 in many of the same comparisons. It is roughly 25 years old, and in excellent condition. See pic below.
The original model 820 was introduced over 10 years ago, and there are reviews both here on CN and on BF that indicated some dislikes regarding the eyecups, the plastic bridge, and the diopter, as well as some other minor issues. Most were quite happy with the optics though. I have never had the opportunity to use the original 820, but the current model 820 does offer very comfortable rotatable eyecups with an appropriate minimum and maximum range that easily allows seeing the full FOV with and without glasses. It also has a thick metal bridge that is plenty sturdy, and a thumb adjusted diopter that I find very easy to use and that doesn't seem to want to move on it's own. The ergonomics also make it very comfortable to hold for extended periods.
Comparing features to my HR/5 Audubon in consideration of my needs and wants, I find the eyecups to be greatest revelation. My HR/5 is tedious to use with glasses. While the eyecups do roll down, they are very stiff and tend to wear quickly depending on how much I use that feature. Further, even with the eyecups rolled down, the eye relief still isn't long enough to allow me to see the entire FOV with glasses anyway. In fact, it's not even close. Because of all this, I tend to only use the HR/5 with my glasses off. The current 820 is about as perfect and as easy as can be in accommodating the use of eyeglasses. So if the optical performance of the new 820 is at least on par with the HR/5, I'm still a leap ahead of the game with the new model.
It really should be noted right from the start that my HR/5 is 20 years old, and has logged many hours of use in it's lifetime. The optics are, nevertheless, clean and aligned, and there are probably only a few cleaning swirls separating the optical conditions of the two. But this 820 is nearly brand new, so it certainly should have a bit of an optical advantage going in.
Unfortunately, the first optical test for the 820 was a bit disappointing. Being the self-proclaimed wide field "nut" that I am, field of view is always the first thing I check. And it was immediately obvious to me that the HR/5 has the wider FOV. The difference wasn't huge, but I estimated it at approximately between 2 and 3 tenths of a degree. However, my disappointment was then a bit tempered by the fact that the very edge of the slightly narrower 820 FOV was actually much cleaner than the very edge of the slightly wider HR/5. So what was lost in FOV wasn't anything that I was going to do much with anyway, and the better outer field corrections of the 820 gave an overall view that was actually more similar to my Swaro 7x42.
So after quickly getting over that one, I noticed yet another obvious difference. The 820 clearly had the brighter image compared to the HR/5, both background and foreground, and it seemed that contrast was somewhat improved. So I did a series of star field tests. I would either begin with the 820 and end with the HR/5, or begin with the HR/5 and end with the 820. In either case, the Swaro was inserted in the middle. All I did was identify each star in a particular grouping and then try to make the same identifications with each binocular. I probably did 15 or 20 of these tests. Whenever I began with the HR/5, it was always rather easy and quick to make the same identifications in the Swaro, and then in the 820. However, whenever I began with the 820, the whole process would take longer. Usually it wasn't the Swaro that took up most of the time, but it was the HR/5. Still, I can only remember a couple occasions where I wasn't eventually able to account for all of the stars in a grouping. And it is a fact that I originally identified those particular "missing" stars in the 820 using averted vision anyway. So while there was clearly a drop in performance with the HR/5, I still was eventually able to see much of what I was looking for in each star field test. The Beehive Cluster proved to be a more difficult test, however, and the 820 clearly provided a better defined image for easier counting.
I also took the opportunity to see how each binocular handled the full moon. With regard to ghost images, the Swarovski 7x42 was clearly the best of the three, with the 820 second and the HR/5 last. As far as putting up the highest contrast lunar image, the 820 actually barely beat the Swaro, and marginally beat the HR/5.
I should also note that despite the smaller scale and FOV, the Swaro 7x42 consistently stayed ahead of the HR/5 and kept up with the 820 throughout the testing. Tight, intense star images seemed to make up for the difference. Overall though, I preferred the larger scale images and wider FOV of the 820.
A couple other reasons to like the new 820... It stands about a half an inch taller because they added a half inch of "dew cap" after the objectives. And even though it's a bit taller, it actually weighs about one ounce less.
So I am quite happy with the new model 820 Audubon. It seems to clearly show that Swift has listened to users and studied all the reviews for input into designing this updated model.
Edited by SMark, 23 June 2016 - 11:52 PM.