Short answer: the SX740 is a 40x compact superzoom, and its main power draw is the zoom motor, optical stabilization, and the screen rather than the sensor itself. One NB-13L II at room temperature, with little zooming and single-frame shooting, will manage roughly 200-250 shots; a travel day of constant zooming drops that to 150-200. Two packs is the floor, and three is sensible for telephoto work.
This class of camera is unusual: the sensor is only 1/2.3 inch with modest pixel count, so per-shot processing costs little, but it is paired with a 40x optical zoom lens and strong stabilization. That combination gives it a power profile completely unlike the G7X you may be used to.
The SX740 drains power differently from a G7X
The zoom motor. This is the biggest variable. Pushing from the wide end to the tele end means a small motor driving the entire lens group forward and back over a long travel. On a 40x body the barrel extends further than the camera is long, and every full sweep draws a substantial pulse of current. For birding or shooting a performance, where you hunt for a subject again and again, a few dozen sweeps can eat a noticeable amount of charge.
Optical stabilization. The longer the focal length, the more handshake gets magnified and the harder the stabilization group has to work. Half-press the shutter at the tele end and you can feel the image “settle” — that is the lens group moving in real time, drawing power continuously.
The screen. The SX740 has no electronic viewfinder, so all composition happens on the rear screen. A screen that is always on and turned up is a steady baseline load, only loosely tied to how many shots you take and closely tied to how long the camera is on.
Autofocus. At the tele end depth of field is shallow and contrast is low, so autofocus has to search back and forth. That costs more than at the wide end and produces more hunting.
How many shots one pack delivers
| Usage | Approximate shots | Notes |
|---|---|---|
| Little zoom, single frames, room temperature | 200-250 | Mostly wide to mid focal lengths |
| Frequent tele zooming | 150-200 | Birding, performances, sports |
| Heavy continuous shooting | Noticeably lower | Write and buffer pressure |
| Occasional video | Counted in minutes, drains faster | Video draw is far above a single frame |
| Cold outdoor use | Two to three tenths less than room temperature | Usable capacity drops temporarily |
Treat that table as a starting point, not a promise. Two people shooting the same 200 frames can use twice the difference in charge — one standing still and composing slowly, the other tracking a bird back and forth at full zoom.
Budgeting batteries for a trip
- Estimate the day’s shot count. City sightseeing usually runs 150-300; nature subjects (birds, animals, flowers) often run 300-500 because of repeated zooming.
- Convert conservatively at 200 shots per pack. 300 shots means two spares, 500 means three. That conversion already accounts for moderate zooming.
- Add the cost of being switched on. Ten hours out means the camera may be on for six or seven, and the screen and stabilization at idle will eat close to another half pack.
- Check for a charging window. If you can charge back at the hotel, carry one fewer. For multi-day camping with no power, plan three per day plus a power bank.
- Add one more for cold trips. Winter, altitude, and early-morning shoots all lower usable capacity temporarily. It recovers at room temperature, but in the moment it is simply not enough.
Power-saving settings and choosing a pack
- Turn off continuous autofocus. Switch to single AF and focus with a half-press; it saves a lot of back-and-forth current.
- Shorten the image review. Do not auto-display for two seconds after each shot; turn it off or set 0.5 seconds.
- Turn off Wi-Fi and Bluetooth. Enable them only when transferring. Constant connection costs real standby power.
- Drop screen brightness one step. Bright outdoor light genuinely needs it; indoors and on overcast days you can turn it down.
- Compose first, then zoom. Point the camera in roughly the right direction before extending to the focal length you want, instead of sweeping from wide all the way to tele while hunting.
- Avoid power cycling. Switching off and on involves the longest barrel travel of all, which costs more than idling. For short pauses, let it sleep.
- Shoot single frames rather than low-speed bursts. Bursts load the write path and buffer, and they draw more power.
Two points on choosing a pack
First, the NB-13L is the only option for this body. Do not try to substitute another model or add an adapter. Second, rotating several packs is more practical than chasing one high-capacity pack — the physical size of the pack sets the capacity ceiling, and expecting one to last all day is unrealistic.
The YO NB-13L II is positioned as a backup: capacity close to OEM, with the improvements in cell consistency and cycle life. For a camera that burns two or three packs a day like the SX740, consistent behavior across packs matters more than a bigger single pack, because you do not want the one you just loaded to drop a bar without warning. For compatible bodies and specs, see the NB-13L II category and the NB-13L category; the G7X and G9X series use the same model.
FAQ
Is one battery enough for a day with the SX740?
For most travel, no. City sightseeing at 200-300 shots plus long hours switched on usually outlasts a single pack before evening. Two is the floor, and three is advisable for telephoto subjects.
Why is the tele end so much more demanding?
Three causes stack up: a long zoom motor travel, larger stabilization compensation, and autofocus that hunts more at long focal lengths. All three get worse as focal length increases.
Can I power the SX740 from a power bank?
It depends on whether the body supports USB power and on the firmware installed; check the manual for your unit. The safer approach is to carry more packs and recharge them in a dock or by direct pack charging, which avoids the heat of charging while shooting.
A pack sat unused for a long time. Is it still usable?
Charge it first and see whether it reaches full normally, then put it in the body and check that the charge reading is stable. Do not use it if it gets unusually hot while charging, if the case has swollen, or if it drops bars quickly once installed. The right storage level for long periods is 40%-60%, topped up every three months.