Photo — Telephoto
#photo/tele · Note 5 of 7 · part of Photography
I do not own one yet. This is the note for when I do.
What the 35mm cannot reach
At ~56mm equivalent (Photo — The kit), everything distant stays distant. No wildlife, no candid street from across a road, no moon bigger than a dot, no compression — that flattened, stacked look that only long lenses give.
What I would buy
| Lens | Reach on APS-C | Why |
|---|---|---|
| RF-S 55–210mm f/5–7.1 IS STM | ~88–336mm eq | The sensible first one. Light, cheap, stabilised, made for this body |
| RF 100–400mm f/5.6–8 IS USM | ~160–640mm eq | Enormous reach for the money. The birds-and-moon lens |
| RF 70–200mm f/4L IS USM | ~112–320mm eq | Optically superb, constant f/4, several times the price |
The 55–210 first. It costs little, weighs nothing, and will tell me within a month whether I actually shoot long or just like the idea of it.
The catch on all of them: they are slow. f/7.1 at the long end is roughly four stops darker than the 35mm at f/1.8. Telephoto is a daylight activity unless there is a tripod involved.
Technique, which changes completely
Shutter speed. The 1/(focal × 1.6) rule bites hard here. At 210mm that is 1/336 → round to 1/500. For birds in flight, 1/1000 to 1/2000. IS helps with shake, not with a bird.
Stability. Long lenses magnify every tremor. Support the barrel, not the body. Tuck elbows in. A monopod is transformative and packs down small.
Depth of field is thinner than you expect. At 210mm and f/7.1, focus is still critical — reach compresses depth as well as distance.
Atmosphere is the real limit. Heat shimmer over a long distance destroys detail no lens can recover. Shoot early, shoot across cool ground.
The moon, specifically
The moon is a sunlit rock, so it is far brighter than instinct suggests. Metering for the black sky around it is what blows it out to a white disc.
- Manual mode
- f/8, ISO 100, 1/125–1/250s
- Manual focus, live view zoomed to 10×
- Spot metering if you stay in auto
At 400mm on APS-C (~640mm eq) the moon fills a useful part of the frame. At 210mm it is small but croppable from 24MP.
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