I've been birding on and off for 44 years now, and recently had the nostalgic urge to document the various combinations of binoculars (bins) and field guides that I've used over the years:
1978: Boots Pacer 8×30 + Usborne Spotter's Guide to Birds
This is the book that started it all. It was a present from my parents on a holiday to the Lake District in 1978. Usborne books were a big presence in my youth (especially The Detective's Handbook), and the illustrations in this guide prompted my interest in nature. My first bins were an own-brand model from Boots the Chemist, but didn't come until Christmas three years later. All glossy black and silver detailing like a Peter Cushing era Dalek.
1990: Swift Audubon HR/5 8.5×42 + Hamlyn Guide to Birds of Britain and Europe
These Swift Audubon bins where my 18th birthday present, and a big step up from the budget Boots ones. Bright image, great field of view, and along with my first 'proper' field guide, my birding became more serious. They were bought from 'InFocus' just outside Coventry, a perfect shop-with-nature-reserve that was ideal for testing optics. Sadly it's no longer in business.

I hadn't looked in this field guide since the mid 90's and found my old birding permit for Draycote Water reservoir in it:

This was when the combination of my pursuing illustration at further education college, and my hobby, made my decision to go on to study wildlife illustration. It turned out there was very little money in it, and the UK already had 5 wildlife illustrators thank you very much, so after college I got a job as a designer instead.
1999: Pentax 8×42 DCF + Collins Bird Guide
I managed to break my Audubons, so with my first freelance work payment in 1999 I bought my first roof prism bins from InFocus. The recently purchased Collins Bird Guide was a revelation - such high quality illustrations, but my copy became chewed by Olive when she was a puppy!
2019: Swarovski EL 8×32 + Collins Bird Guide iOS app
The boat was well and truly pushed out, and I got these amazing Swarovski bins for my 47th birthday from The Birders Store in Worcester. Compact, light (which is really important these days) and a wonderful large field of view. Even though they're only a 30mm objective lens, the image is so bright that I felt I didn't need the much heavier 8×42's. The ability to have a field guide on my phone means I can easily carry it out with me, as well as get extra features like bird songs/calls and video.
Birding is very much a relaxing, mindfulness, anxiety-buster for me. At the end of the day, the equipment doesn't matter as much as the actual time spent doing it. It's more that these bins & field guide combinations represent milestones in my life.