Within a month or so, it's the first time I'll see fireworks as an owner of a good camera and naturally I'm planning to take photographs of them.

By researching various fireworks photography sources, I have found that the lens does not need a fast aperture: f/8 is plenty, some sources recommend as low as f/22. ISO speed will be of course 100. Shutter speed will naturally be bulb exposure on a tripod with remote camera connect smartphone app.

However, focusing will be a problem. I have understood that manual focus to infinity should be used, with the focusing done during daylight. This makes it problematic to use some externally zooming lenses as they may not be parfocal and will shift focus during transportation. Thus, the lenses I'm most interested in using for fireworks photography are:

  • Canon EF 85mm f/1.8 USM prime
  • Canon EF 135mm f/2L USM prime
  • Internally zooming (probably non-parfocal?) Tamron EF 70-210mm f/4 Di VC USD
  • Externally zooming electronically parfocal Canon RF 24-240mm f/4-6.3 IS USM

With prime lenses, there's no focus shift during zooming so I can easily set the focus and try to avoid accidental refocusing during transportation. With Tamron EF 70-210mm internal zoom, I can set the zoom to the desired focal length prior to focusing during daylight and then maintain that zoom setting, but then the advantage vs a prime would be minor unless the focal length I'll choose is far away from 85mm and 135mm.

The problem of non-parfocality made me consider Canon RF 24-240mm. I understand that while not truly mechanically/optically parfocal, it maintains focus by shifting focus electronically during zooming. Also, being focus-by-wire, there's no possibility to accidentally refocus during transportation if the camera is turned off.

My question is: do the electronically parfocal Canon RF lenses maintain infinity focus well enough for fireworks photography that I can focus to infinity at one focal length (probably the longest) and use the lens at any focal length afterwards without needing to refocus?

Of course one option could be to use several lenses with different focal lengths, but changing a lens outdoors with air dark from particulate matter from fireworks sounds like a possibility to self-caused sensor cleaning need, considering that my mirrorless camera lacks mirror protecting the sensor (obviously) and the mechanical second-curtain shutter does not close to protect the sensor when the camera is off. Also, reacting to changes in firework shooting distance is easier and faster with zoom than by changing lenses.

I calculated that at 135mm and f/11, hyperfocal distance is 53.8 meters. Thus, even a shift from infinity to 30 meters would be a problem.

  • This question is filled with assumption after assumption that may or may not necessarily be true for the stated use case. – Michael C Dec 4 '19 at 5:38

If you have use of RF lenses, you have a modern mirrorless camera. If you have a modern mirrorless camera, you have manual focus with magnification at your disposal, and an EVF system that can deal with showing you something as bright as a fireworks spark without trouble.

You will be able to refocus with precision at any time. In any case, unless your lens has some way to lock focus, you W I L L mess up manual focus accidentally many times handling your camera in the dark. In any case, you would want to put marking stickers on your lens (which you might not be ABLE to do with some modern lenses that don't have a mechanically hard-coupled focusing ring).

The advice "focus to infinity during daylight" sounds like advice for using DSLRs without live view, which can neither magnify to focus nor give you sufficient view of the scene in low light (especially cheap pentamirror DSLRs).

As for shutter speed, there appear to be multiple schools to fireworks photography ... one that loves bulb exposures and picturing the whole fireworks shape, another that loves pinpoint sharp frozen views (start at 1/60th, f/2.8-f4 and ISO 400-800 and experiment until you nail it). Expose for context (crowds, buildings etc) more than for the fireworks themselves (well, don't overexpose them until they are blowing out). Don't overdo the ISO if you can avoid it (almost-dark backgrounds or smoke reflections can look really murky at high iso; also you lose dynamic range at high ISO, making terminally blown highlights or even channel saturation more likely), don't rely on your lens being capable of resolving fireworks dots cleanly at fully open aperture until you tested it.

The recommendation to use extremely slow apertures might be misguided film-era half-wisdom. As long as your focus is under control, usually the "cleanest" aperture is 2 or 3 stops down from wide open. f/16 and slower can actually get you in harms way (diffraction, dust...) with digital cameras.

Unless you are shooting the fireworks from a raised position far behind the crowd, bring something wide angle capable. Tele can be nice for some detail shots ... but many professional fireworks displays are 24mm-equivalent-frame-filling-BIG from a crowd perspective. If you have a reasonably fast 20mm or 24mm prime, bring it. If you have something like the Sigma 24-60 f/2.8 EX DG (optically great for fireworks IMHO, albeit easily upset handling in the dark), bring it.


Seriously, at f/22, you don't need a very accurate focus, setting the lens to infinity should be good enough, especially if you use "bulb" exposure, that coalesces the fireworks to long blurry streaks anyway(*).

(*) If you want to see actual shapes, use a much shorter exposure (around 1/20s...).

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