Canon EF 135mm f/2L on the R8 and R100: Does It Add Anything to an 85mm and 100mm Kit?
A photographer running two Canon mirrorless bodies, an EF-to-RF adapter, and a pair of fast EF telephoto primes sits in one of the most common upgrade traps in the adapted-lens world: the kit already works, the next lens is legendary, and nobody can quite explain what it would actually change. The specific case here is an EOS R8 and an EOS R100 paired with the EF 85mm f/1.8 USM and the EF 100mm f/2 USM, with the EF 135mm f/2L USM as the candidate purchase.
The honest answer requires separating three different questions that usually get collapsed into one: whether the focal length is missing, whether the optical quality is missing, and whether the lens will physically fit the way the photographer shoots.
The redundancy is already in the bag, and it isn’t the 135
The 85mm f/1.8 and the 100mm f/2 are the closest thing Canon ever made to the same lens twice. Both are USM primes from the late 1980s and early 1990s, both built around eight-blade apertures and similar double-Gauss-derived designs, both take 58mm filters, both weigh in the 425-460g range, and both focus down to roughly 0.85-0.9m. Their rendering is nearly indistinguishable in side-by-side comparisons: the same slightly nervous background transition, the same mild field curvature, the same longitudinal chromatic aberration that paints purple onto specular highlights at f/1.8 and f/2.
The gap between them is 15mm of focal length, which on a full-frame body translates to a framing difference a single step backward erases. Photographers who own both almost universally report that one of them stops leaving the house within a few months. That is the real redundancy in this kit, and adding a third lens does not resolve it.
The 135mm f/2L is not a third member of that family. It is a different tier of glass with a different job.
What the 135L actually adds
The optical case is straightforward. The EF 135mm f/2L USM carries two UD-glass elements specifically to correct secondary spectrum, which is the exact failure mode that makes the 85mm f/1.8 wobble at wide apertures. The 135L is sharp at f/2 in a way neither of the other two lenses is sharp at their maximum apertures — not marginally, but in the sense that stopping down is a creative choice rather than a corrective one.
The second gain is background separation, and this is where focal length and aperture compound. At f/2, a 135mm lens produces roughly 2.5 times the background blur of an 85mm at f/1.8 for an equivalently framed subject, because blur scales with the physical aperture diameter — 67.5mm on the 135, versus 47mm on the 85. The backgrounds do not just soften, they collapse into wash. Combined with the compression that a 135mm focal length applies to depth, this is a look the current two lenses cannot approximate at any setting.
Third, and least discussed: the 135L renders skin and hair transitions cleanly at wide apertures without the smeared edges that show up on the older primes when shooting at f/1.8 or f/2. For photographers who deliver at 100% crop, that difference is visible without pixel-peeping.
The working-distance problem, which is where most 135L purchases go wrong
Focal length is a geometry constraint before it is an aesthetic one. On a full-frame R8, framing a subject with a 135mm lens requires approximately:
- Tight headshot: 2 metres
- Head and shoulders: 3.5 metres
- Half body: 5.5 metres
- Full body: 10 metres
By comparison, the 85mm covers the same four framings at roughly 1.3m, 2.2m, 3.6m, and 6.5m. Indoors, that difference is the difference between working in a normal living room and not working at all. A 10-metre full-body shot is a parking lot, a park, or a gymnasium — not an apartment, not a hotel room, not most studio spaces under 40 square metres.
On the R100 the math becomes considerably less forgiving. The 1.6x crop factor turns the 135mm into a 216mm equivalent field of view. That is not a portrait lens on that body; it is a candid-across-the-street lens. It will produce head-and-shoulders frames from 3.5 metres and nothing wider than a half-body from inside most rooms.
Which raises the point that should probably settle the question on its own: on the R100, the 85mm f/1.8 already delivers a 136mm equivalent field of view. The photographer asking whether to buy a 135 already owns the 135 field of view, on one of the two bodies, in a lens that is 325g lighter. What the crop body cannot replicate is the optical quality and the physical aperture — but the framing is already available.
Stabilization is the second constraint, and it is not negotiable
The EF 135mm f/2L has no image stabilization. Neither the EOS R8 nor the EOS R100 has in-body stabilization — the R8 offers digital IS for video only, which crops and does nothing for stills. This means the entire stabilization burden falls on shutter speed.
The traditional 1/focal-length guideline suggests 1/135s. On a 24MP full-frame sensor with modern output expectations, 1/250s is the realistic floor for consistently clean handheld frames, and 1/320s if the subject is moving at all. At f/2, that is workable outdoors and in bright interiors. In dim rooms it forces ISO 3200 and up on the R8, and considerably worse on the R100, whose smaller sensor and older processing handle high ISO less gracefully.
The comparison matters: the 85mm f/1.8 at 1/160s and f/1.8 buys roughly one and a half stops of light-gathering headroom over the 135L at 1/250s and f/2. In marginal indoor light, the older, cheaper, worse lens is the one that comes home with usable frames.
Handling, adapter behaviour, and the practical realities
At 750g and 112mm long, the 135L is nearly twice the mass of either current lens, and it mounts through an adapter that adds another 24mm of length and roughly 110g. On an R8 — a body that weighs 461g with battery and card — the resulting combination is heavily front-biased. It is manageable, but it is a two-hand rig, and it does not disappear into a shoulder bag the way the 85mm does.
Autofocus through the EF-to-RF adapter is genuinely good. The 135L uses ring-type USM, which the RF bodies drive quickly and quietly, and Dual Pixel AF with eye detection works normally. The lens does hunt slightly more than native RF glass in low contrast, and its servo tracking for video is less refined than a modern RF design, but for stills the adapted experience is close to native.
One underrated bonus: the 135L is fully compatible with the EF 1.4x and 2x extenders, converting it into a 189mm f/2.8 or a 270mm f/4. For anyone shooting outdoor events or wildlife occasionally, that is real added range from a lens already owned.
The used market
The 135L has been in production since 1996 and copies circulate constantly. Prices vary widely by condition and region — bargain copies with cosmetic wear appear at the low end, while clean examples with hood and caps command a substantial premium. The optical formula never changed, so an older copy with clean glass performs identically to a recent one. The failure points to check are the USM ring (listen for grinding), the focus-distance window for haze, and the front element for coating damage. Patience pays here; supply is steady and there is no reason to overpay for the first listing found.
The decision
Buy the 135L if portraits are shot primarily outdoors or in large spaces, if the R8 is the main body, and if the specific look — extreme subject isolation, compressed background, clinical sharpness wide open — is the goal rather than a nice-to-have. In that scenario it is not an incremental upgrade; it is the only lens in the discussion capable of the result.
Skip it if most shooting happens indoors, in tight rooms, or on the R100. In that case the money is better spent resolving the redundancy that already exists: sell either the 85mm or the 100mm, and put the proceeds toward a wide or normal prime. A 35mm or 50mm fills a genuine hole in this kit. A third short telephoto narrows an overlap that is already too narrow.
The lens that improves a kit is rarely the best lens available. It is the one covering the ground nothing else covers.