Best Lens for OM SYSTEM PEN
The $1,099 OM SYSTEM PEN kit already includes the new sealed 14-42mm F3.5-5.6 III. The first extra lens that keeps the 393 g rangefinder pocketable — and keeps the body’s IPX1 honest — is the M.Zuiko Digital 17mm F1.8 II.
Our Top Picks at a Glance
Reviewed September 2026 · OM SYSTEM PEN · 393 g · IPX1 body · kit 14-42 III 125 g / 46 mm · Live ND ND2–ND16 already in the CP button
34mm-equiv, 112 g, 46 mm, IPX1. The sealed street prime that matches this PEN.
Check Price at Amazon Read full review ↓50mm-equiv, 156 g, 46 mm, IPX1. Same seal family, $100 less than the 17mm II.
Check Price at Amazon Read full review ↓90mm-equiv, 116 g, 37 mm. Not weatherproof. The cheap portrait prime.
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| Lens | Equiv. | Weight / filter | Seal | Buy |
|---|---|---|---|---|
| 17mm F1.8 II | 34 mm | 112 g · 46 mm | IPX1 — matches the PEN | Check price |
| 25mm F1.8 II | 50 mm | 156 g · 46 mm | IPX1 — same family | Check price |
| 45mm F1.8 | 90 mm | 116 g · 37 mm | No — dry-day portrait | Check price |
| 14-42mm F3.5-5.6 III | 28–84 mm | 125 g · 46 mm | IPX1 kit zoom, not a first extra | Check price |
How We Picked
Three official facts. This is a 393 g IPX1 PEN, not an OM-1 with a 12-40 PRO on the front, and not the 12mm F2 “80 hours in the rainforest” on this site.
- Match the body seal, then the pocket. OM’s launch release: first PEN with IPX1 splash sealing, and sealing counts only with a dust- and splash-proof lens. Body $999.99; 14-42 III kit $1,099.99; double kit with 40-150 R $1,299.99. B&H: 125.8 × 74.5 × 43.3 mm, 393 g with battery, 5.5-stop IBIS class, Live ND lives on the CP button (ND2–ND16). An ND filter is not the first accessory.
- Do not repurchase the kit zoom as Overall. 14-42mm F3.5-5.6 III: 125 g, 46 mm, 28–84mm-equiv, IPX1, click-retract (no lock switch), $349.99 standalone, closest focus 0.13 m at 14 mm. If the $1,099 kit is already on the desk, the first extra lens is a fast prime, not a second copy of that zoom.
- Pick the sealed F1.8 II primes that share the kit’s 46 mm thread. 17mm F1.8 II: 34mm-equiv, 112 g, 57.6 × 37.6 mm, 46 mm, IPX1, $649.99. 25mm F1.8 II: 50mm-equiv, 156 g, 59.4 × 42 mm, 46 mm, IPX1, $549.99. 45mm F1.8: 90mm-equiv, 116 g, 37 mm, weatherproof No. 12-40 PRO and 300mm PRO stay on the OM-1 wildlife pages.
Detailed Reviews
M.Zuiko Digital 17mm F1.8 II View on Amazon View on B&H
| SKU | M.Zuiko Digital 17mm F1.8 II — OM SYSTEM |
|---|---|
| Angle | 17 mm · 34mm-equiv · 65° · F1.8–F22 |
| Build | 112 g · 57.6 × 37.6 mm · 46 mm · LC-46 · LH-49B |
| Seal | IPX1 splash / dust / freeze — matches the PEN footnote |
| Focus | 0.25 m · 0.08× (0.16× equiv.) · MSC |
| Price | $649.99 |
Why it fits the PEN. A 34mm-equivalent on a 393 g rangefinder is the everyday street width. The Mark II adds the seal the original 17mm F1.8 never had, so a sudden rain does not turn the IPX1 body into a paperweight. 46 mm matches the kit zoom’s thread. 112 g keeps the kit under half a kilo with a card and the BLS-7.
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M.Zuiko Digital 25mm F1.8 II View on Amazon View on B&H
| SKU | M.Zuiko Digital 25mm F1.8 II — OM SYSTEM |
|---|---|
| Angle | 25 mm · 50mm-equiv · 47° · F1.8–F22 |
| Build | 156 g · 59.4 × 42 mm · 46 mm · LC-46 |
| Seal | IPX1 — same Mark II family as the 17mm |
| Focus | 0.25 m · 0.12× (0.24× equiv.) |
| Price | $549.99 |
Why it is Value. Same weather rating, same 46 mm thread, $100 under the 17mm II. 156 g is still a PEN-scale prime. Take this when the kit zoom already covers 28mm-equiv and the missing look is a sealed 50, not a wider street view.
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M.Zuiko Digital 45mm F1.8 View on Amazon View on B&H
| SKU | M.Zuiko Digital 45mm F1.8 — OM SYSTEM |
|---|---|
| Angle | 45 mm · 90mm-equiv · 27° · F1.8–F22 |
| Build | 116 g · 56 × 46 mm · 37 mm filter |
| Seal | Weatherproof: No |
| Focus | 0.50 m · 0.11× |
Why it is Budget. 116 g is PEN-scale. 90mm-equivalent is the cheap portrait look the 14-42 III cannot fake at F5.6. OM’s own spec table says it is not weatherproof, so the body’s IPX1 stops at the mount in rain. Different filter (37 mm) than the 46 mm kit / F1.8 II pair.
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If You Need Something Else
The kit zoom is the sealed walk-around if the body was bought bare. 12-40 PRO is the OM-1 — too much lens for a 43.3 mm-deep PEN.
M.Zuiko 14-42mm F3.5-5.6 III View on Amazon View on B&H
| SKU | 14-42mm F3.5-5.6 III · $349.99 standalone |
|---|---|
| Build | 125 g · Ø60 × 50.5 mm · 46 mm · IPX1 · click-retract |
| Close focus | 0.13 m at 14 mm · 0.26× (0.53× equiv.) |
| PEN job | Buy this if the body is $999 bare. Do not rebuy it as the first prime. |
OM’s IBIS footnote for 5.5 stops was measured with this lens at 42 mm. The double kit’s 40-150 R is a second zoom, not a substitute for a sealed F1.8. Leave 12-40 PRO and 300mm PRO on Best Telephoto Lens for OM SYSTEM OM-1.
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M.Zuiko 12-40mm F2.8 PRO View on Amazon View on B&H
| This body | 393 g rangefinder · 43.3 mm deep · IPX1 splash, not an OM-1 weather tank |
|---|---|
| That lens | The standard PRO zoom on OM-1 pages. It works. It is the wrong scale. |
A sealed F1.8 II keeps the PEN a PEN. The PRO zoom turns it into a short OM-5. Use the CP button’s Live ND instead of hanging filters off a 12-40 for water-blur.
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Frequently Asked Questions
Why 17mm F1.8 II is Overall instead of the kit 14-42 III
The $1,099 kit already includes the 14-42 III. Overall is the first extra lens. The 17mm F1.8 II is 112 g, 34mm-equiv, IPX1, and shares the kit’s 46 mm thread. The zoom is the sealed walk-around, not a second purchase for kit buyers.
Why 17mm II instead of the older 12mm F2
This site’s older OM System primes page led with 12mm F2. That is a 24mm-equiv landscape, and it is not the IPX1 Mark II family. The PEN’s job is a pocket rangefinder. 34mm-equiv sealed is the match.
Whether the body’s IPX1 works with 45mm F1.8
OM’s launch footnote: splash sealing applies when the PEN is paired with a dust- and splash-proof lens. OM lists the 45mm F1.8 as weatherproof: no. Rain is a 17mm II or 25mm II or 14-42 III job.
Whether a 46 mm filter set covers the kit
Yes for 14-42 III, 17mm F1.8 II, and 25mm F1.8 II. The 45mm F1.8 is 37 mm. Live ND ND2–ND16 is already on the CP button, so an ND filter is not the first PEN accessory.
What the double kit 40-150 R is for
The $1,299 kit adds the 40-150mm F4.0-5.6 R. That is a light tele zoom, not a sealed F1.8 and not a 300mm PRO. Buy the double kit for reach. Buy 17mm II or 25mm II for an extra sealed prime.
Final Verdict
For the OM SYSTEM PEN, buy the 17mm F1.8 II as the first extra lens. Take the 25mm F1.8 II when the look is a sealed 50. Take the 45mm F1.8 on dry portrait days. Leave the 14-42 III in the kit box, and leave 12-40 PRO on the OM-1. This body is 393 g and IPX1 only with a sealed lens.