Pentax Papilio II 6.5x21 vs Pentax Papilio II 8.5x21
Quick take: The Pentax Papilio II 6.5x21 costs $20 less; the Pentax Papilio II 8.5x21 reaches farther (8.5x vs 6.5x); the Pentax Papilio II 6.5x21 has a wider field of view (394 vs 315 ft @ 1000 yds).
Field of view, to scale
Top-down view · drawn to true scale — no exaggeration
Which one to buy
Butterflies that won't sit still against beetles that will: that is the whole split between these two Papilio IIs. They share the 1.6 ft close focus no other binocular matches, the 10.2 oz body, 15mm of eye relief, the built-in tripod thread and the same lack of waterproofing. The 6.5x21 costs $20 less.
The 6.5x gives you a 394 ft field and a 3.2mm exit pupil; the 8.5x gives 315 ft and 2.5mm. Owners of both agree on what that means. The wider 6.5x makes it far easier to find a butterfly again after it hops sideways, and it stays brighter as light fades. The 8.5x makes small, slow subjects fill much more of the view, which owners describe as field-microscope territory for beetles, wildflowers and pond life, and it reaches farther for casual birding. In exchange it dims sooner, and the extra power shows more hand shake.
Optics are good on both by owner account: minimal color fringing and little field curvature on the 6.5x, sharp nearly to the edge on the 8.5x. Both have the same small, low-geared focus wheel that takes about three turns across its range, no objective covers and a diopter that doesn't lock. Light drizzle is about the limit for either, so neither belongs in a kayak.
As a first Papilio, the 6.5x is the more forgiving all-rounder and the one owners steer butterfly chasers toward. The 8.5x is the specialist for subjects that hold still.
Pentax Papilio II 6.5x21
For chasing butterflies and other quick insects, with a brighter, easier view, at $20 less.
Pentax Papilio II 8.5x21
Worth the extra $20 for slow, small subjects like beetles, wildflowers and pond life, plus a little more reach on distant birds.
| Spec | Pentax Papilio II 6.5x21 | Pentax Papilio II 8.5x21 |
|---|---|---|
| Approx. price | ~$129 | ~$149 |
| Use case | General Purpose | General Purpose |
| Magnification | 6.5x | 8.5x |
| Objective | 21mm | 21mm |
| Exit pupil | 3.2mm | 2.5mm |
| Field of view | 394 ft @ 1000 yds | 315 ft @ 1000 yds |
| Eye relief | 15mm | 15mm |
| Close focus | 1.6 ft | 1.6 ft |
| Prism | Porro | Porro |
| Glass | BaK-4 | BaK-4 |
| Coating | Fully Multi-Coated | Fully Multi-Coated |
| Weight | 10.2 oz | 10.2 oz |
| Dimensions | 4.5 x 4.4 in | 4.6 x 4.3 in |
| Warranty | 25-Year Limited | 25-Year Limited |
Feature comparison
Pentax Papilio II 6.5x21
- ✗ED Glass
- ✗Phase-Corrected
- ✗Dielectric Coating
- ✗Waterproof
- ✗Fogproof
- ✗Image Stabilized
- ✓Tripod Adaptable
- ✗Magnesium Body
- ✗Locking Diopter
Pentax Papilio II 8.5x21
- ✗ED Glass
- ✗Phase-Corrected
- ✗Dielectric Coating
- ✗Waterproof
- ✗Fogproof
- ✗Image Stabilized
- ✓Tripod Adaptable
- ✗Magnesium Body
- ✗Locking Diopter
What birders say
Pentax Papilio II 6.5x21
- ✓The 1.6 ft close focus is unmatched by any other binocular - the convergent objective system slides the lenses together as you focus near, so both barrels stay on target without the image collapsing
- ✓Functions as a hands-free magnifying glass for butterflies, dragonflies, flowers, and museum exhibits - a capability reviewers say no competitor replicates
- ✓The 6.5x version's wide 394 ft field of view makes tracking fast-moving insects much easier than the 8.5x sibling - the forum consensus pick for butterfly chasing
- ✓Genuinely good optics, not just a party trick: testing found minimal field curvature, virtually no color aberration, and no color bias
- ✓Featherweight at 10.2 oz and compact enough that reviewers say you forget you're wearing it
- ✓Owners describe it as the most fun binocular they own - close-up bugs one minute, birds and even the moon the next
- ✓Helical twist-up eyecups with three stable click positions and adequate 15mm eye relief work with glasses
- ✓Built-in quarter-inch tripod thread - no special adapter needed for steady close-up study
- ✗Not waterproof or fogproof - fine in light drizzle but a real limitation for a nature binocular that lives outdoors
- ✗Small 21mm objectives and 3.2mm exit pupil mean it won't be bright in dim conditions - dawn, dusk, and forest shade are not its element
- ✗A bit of blurriness at the outer field edges noted in testing
- ✗6.5x is limited reach if this is your only binocular - distant birds stay distant
- ✗Small focus wheel takes roughly three full rotations across its range - precise, but slow, and tricky with gloves
- ✗No objective lens covers included
- ✗Diopter ring doesn't lock
- ✗Thin, unpadded neck strap is a weak point in an otherwise thoughtful package
Pentax Papilio II 8.5x21
- ✓Same unmatched 1.6 ft close focus as the 6.5x, but with 8.5x magnification - small, slow insects fill dramatically more of the view at arm's length
- ✓Forum users specifically favor the 8.5x for slower and smaller subjects, where the extra power reveals detail the 6.5x can't
- ✓Expert testing found the image sharp from center nearly to the edge with only minimal softening
- ✓Chromatic aberration control rivals far costlier glass - just a very thin greenish fringe on the harshest high-contrast edges
- ✓Won a best-compact award from a major review site, which scored it 75% overall
- ✓Low-geared three-turn focus makes critical focusing at 20 inches genuinely precise - fine-tuning is a breeze
- ✓Twist-up eyecups with three firm click-stops and 15mm eye relief let eyeglass wearers see the full field without tunneling
- ✓Thoughtful extras: snug custom case, quick-attach strap system, and a built-in quarter-inch tripod thread
- ✗Tiny 2.5mm exit pupil is the dimmest in the Papilio family - image brightness drops off noticeably in dusk, heavy shade, or dim interiors
- ✗Narrower 315 ft field of view makes finding and tracking fast-moving butterflies harder than with the 6.5x - the forum consensus favors the 6.5x for quick subjects
- ✗8.5x magnification amplifies hand shake, both up close and at distance
- ✗Not waterproof or fogproof - reviewers say light rain is acceptable but rule it out for canoeing, kayaking, or wet climates
- ✗No objective lens covers included
- ✗Small 17mm focus wheel is difficult to operate in winter gloves
- ✗Diopter ring doesn't lock
- ✗The low-geared focus that helps at macro distances makes rapid refocusing on distant subjects slower
Pentax Papilio II 6.5x21 vs Pentax Papilio II 8.5x21: common questions
Should I get the Papilio II 6.5x21 or the 8.5x21 for butterflies?▾
The 6.5x21 for most butterfly watching. Owners say its wider 394 ft field makes tracking fast-moving insects much easier than the 8.5x's 315 ft, and its larger exit pupil keeps the image brighter in shade.
Is the Papilio II 8.5x21 better than the 6.5x21 for birds?▾
Somewhat. Owners call the 8.5x the more capable distance glass of the two, though its 2.5mm exit pupil dims quickly in low light and the magnification shows hand shake. Neither is meant to be your only binocular for dawn birding.