Hi JB,
I’m not an expert on these so others may chime in . . .
In 1999 Nikon introduced the 8x42 and 10x42 HG roof prism binoculars, which were designed to compete with the alpha offerings of Zeiss, Leica and Swarovski
(see the cross-section images that I’ve previously posted at:
https://www.birdforum.net/showthread.php?t=385267 )
Prior to this Nikon had offered various roof prism models with lesser quality and features
In 2002 Nikon introduced the first Monarch branded models, initially with 42mm objectives. They were typically designated ATB in the USA and DCF in Europe
Then x36 and x56 models were added in 2006. All were a step down from the HG line but were generally upper mid range in terms of characteristics
From the start they were phase coated. And there was at least one upgrade
A 2010-2011 catalogue (verses a 2009-2010 one) indicates that by then the x42 models had dielectric prism coating (verses 'high-reflection mirror-coating')
- see the attached page, along with the specification tables from the 2010-2011 catalogue
As Bob indicates, a common characteristic was a relatively narrow FOV
A 2010 review by Jan Miejerink of several models, along with comparison to the HG line, can be found at:
https://tvwg.nl/testrapporten/kijkers/nikon_highgrade_monarch.shtml
(if you open the Google Translate application, paste the address into the left panel and then click on the right panel, you’ll get a translated version)
- - - -
The Monarch 7’s were first in a 2012-2013 catalogue, and by 2013-2014 the original Monarch’s were no longer listed
John