1. Use a solar filter
Don’t point your camera directly into the sun! If you plan to shoot outside of totality (the period where the sun is completely obscured by the moon), you will need to use a solar filter to protect your lens and camera sensor. Solar filters are designed not only to reduce light entering the lens, but also reject IR and UV light. The reduction in light—which is far more dramatic than that of a typical neutral density filter—will allow you to avoid overexposing the bright sun detail. This is difficult to achieve without a filter, even with a small aperture and the advent of faster electronic shutter speeds.
When shooting during totality, however, you will find you need to remove the solar filter since the opposite requirement is now true: you will need as much light hitting the sensor as possible!
2. Bring a sturdy tripod
Do use a tripod (preferably a sturdy one that can accommodate the weight and balance of a telephoto lens). You may need to use very low shutter speeds to capture faint detail during totality, which will prove difficult, if not impossible, handheld.
3. Capture a range of exposures
Use bracketing to capture a range of exposures for each shot. Since the time you’ll have is fleeting, setting up bracketing on your camera will help you achieve the most suitable exposure by having several to choose from.
You can also merge the different exposures together—using Affinity Photo’s HDR Merge, for example—which will align them and then pick the most detailed pixel at each location. The merged image can then be tone mapped if required, or simply worked on but with the benefit of a higher signal-to-noise ratio and 32-bit precision editing (meaning less noise and banding).
4. Use a telephoto lens
In terms of focal length, you will typically be looking at longer telephoto lenses if you want a really impressive image that fills the frame—think 600mm and higher. Don’t forget to take into account your sensor’s crop factor. A micro four thirds camera with a 300mm lens, for example, will have an effective focal length of 600mm. Add a 2x teleconverter to that and you have 1200mm. Even with this focal length, some cropping may be required!
During totality, this long focal length requirement could be relaxed slightly, since you’ll also want to capture the corona detail around the edges of the sun. Using a zoom telephoto lens (as opposed to a prime) will give you more flexibility here and save you the time of having to swap lenses.
5. Go for landscape shots
If you don’t have access to a long telephoto lens, all is not lost: consider acquiring landscape shots, which can add some great context to the event happening in the sky. You may, of course, have to pick your location more carefully for this approach. You will absolutely want to bracket your exposures as well and consider HDR merging or exposure blending in post-production since the difference in brightness between the sun and foreground will be huge.
6. Shoot manual
In terms of camera settings, there is nothing too dramatic to consider here: keep your ISO low (native/base is good) and your aperture wide open (or close to wide open if your lens isn’t very performant at its largest aperture). With a solar filter attached, you’ll probably find you won’t need to stop down at all. During totality (with the solar filter removed), you may have to go down to very low shutter speeds to capture the dimmer detail.
7. Use an electronic shutter
In addition to a tripod, consider using an electronic shutter feature if your camera has one. Some camera models may reduce the readout precision (e.g. from 12-bit to 10-bit) when using electronic shutter, which may put you off, but if you’re bracketing your exposures and merging in post-production you can mitigate any loss in quality here.
8. If your camera has it, use live view
Focussing can be tricky to get right. Obtaining accurate focus is much easier with modern cameras that have live view, as they often allow you to “punch in” and see a portion of what’s being imaged. Focus peaking can also be enabled so you’ll get further visual confirmation that your target is sharp.
If you’re really unsure, try pointing your camera towards a very distant landmark at horizon level and focusing on that. Take a test shot and make sure it’s sharp, then lock your focus and move back to composing for the eclipse.