Is anyone able to list the history of the Swift 820 binoculars. For example, when were they first released, when were significant changes made to these binoculars and what were these changes? How does the 820T differ from the 820, if at all? When I look at the 820 for sale at the moment on Amazon it is designated the 820T (https://www.amazon.com.au/gp/product/B00009XW5N/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1) but looks different to the 820T advertised at swift-sportsoptics.com. Which is the correct photo of the 820T? I am confused.