8-25x super zoom lenses

Introduction

a holy grail of lens design for many people would be a compact super zoom lens with high image quality across the zoom range at a reasonably affordable price, preferably with a relatively wide aperture, weathersealing and image stabilisation with a wide angle coverage starting around 24mm in full frame terms
Olympus has created an 8x lens which fits the above criteria - the Olympus mZD 12-100mm f/4 IS PRO lens which makes a great travel lens with high image quality, 6.5EV Dual IS image stabilisation (can hand hold wide angle to 2-8 secs with care!) and weathersealing
Tamron has created the Tamron 18-400mm f/3.5-6.3 APS-C lens which gives 22x zoom although it is not as weathersealed as the Olympus option, and the image stabiliser is not as good and is not as sharp, particularly once you get past 100mm while the wide end is limited to only 29mm which is problematic for the travel photographer

designed for APS-C sized sensors which gives 29-640mm field of view in full frame terms
moisture-resistant and dust resistant
optical image stabiliser
zoom lock
16 elements in 11 groups
7 rounded blades
works with Tamron’s TAP-in console system for fine-tuning focus
reviews:
- https://fstoppers.com/originals/only-camera-lens-youll-ever-need-fstoppers-reviews-tamron-18-400mm-f35-63-di-ii-245480
  - lots of distortion at the wide end and lots of pincushion starting around 50mm
  - CA can be an issue
- https://www.ephotozine.com/article/tamron-18-400mm-f-3-5-6-3-di-ii-vc-hld-review-31259
  - best image quality wide open is at 18mm
  - at 200mm onwards need to shoot at f/11 to get sharp images in the centre (edges remain soft)
  - mod CA at edges