Understanding the Trade-Off: Why High-Speed Sync (HSS) Isn’t Always the Best Choice

High-Speed Sync (HSS) is a feature on many flashes and strobes that allows you to use shutter speeds faster than your camera’s native maximum flash sync speed (often around 1/200th or 1/250th of a second). It sounds brilliant and I have used it extensively, however while this sounds incredibly useful—especially for freezing action or shooting wide open in bright sunlight—it comes with significant trade-offs that often make it the less desirable choice for professional results.

Here is a detailed look at why it’s generally best to avoid using HSS when possible and opt for alternative methods.

1. Massive Loss of Flash Power

The primary and most critical drawback of HSS is the dramatic reduction in effective flash power.

To understand the power loss, you must understand how a focal-plane shutter works:

• At slow shutter speeds (below the max sync speed), the first curtain opens completely, the flash fires a single, full-power burst while the sensor is fully exposed, and then the second curtain closes.

• At high shutter speeds (when using HSS), the second curtain begins to close before the first curtain has fully opened. This means the sensor is never entirely exposed at once. To light the entire frame, the flash must fire a rapid, continuous sequence of low-power pulses (a “strobe” effect) across the duration of the shutter’s travel.

The Resulting Power Loss

Because the flash is effectively turned into a rapid, continuous light source instead of a single powerful burst, the amount of light hitting any single point on the sensor at any given time is drastically reduced.

• This power loss can be two to four stops (a 75% to 94% reduction in light output) compared to the flash’s full power at the maximum sync speed.

• This means you lose a substantial amount of range and have to place your flash much closer to the subject, often defeating the purpose of using a powerful strobe.

2. Reduced Light Quality and Colour Shift

HSS can subtly, but noticeably, impact the quality and consistency of your light.

• Uneven Exposure: In some cases, especially with lower-end systems or at extremely high shutter speeds, the pulsating nature of the light can lead to minor vertical banding or a slight gradient of exposure across the frame as the shutter curtains travel.

• Colour Shift: Due to the flash firing a rapid series of low-intensity pulses instead of a single full-power one, the flash tube’s colour temperature can sometimes vary, leading to a slight colour shift that requires more correction in post-processing.

3. Slower Recycle Times and Higher Battery Drain

Constant, rapid pulsing of the flash tube in HSS mode demands a lot of power.

• Increased Strain: The electronics are working much harder, leading to significantly slower flash recycle times compared to a full-power single burst at the sync speed. This can make rapid shooting difficult.

• Battery Drain: The continuous power consumption dramatically shortens the battery life of both on-camera flashes and powerful battery-powered strobes.

Better Alternatives to HSS

If your goal is to darken a background or shoot with a wide aperture in bright conditions, there are more effective, power-efficient, and quality-preserving techniques than relying on HSS.

1. The Power of Neutral Density (ND) Filters

The best solution for using flash in bright light with a wide aperture is to employ a Neutral Density (ND) filter.

• How it Works: An ND filter is a darkened piece of glass placed over the lens that uniformly reduces the total amount of light entering the camera.

• The Benefit: By using an ND filter (e.g., a 3-stop or 6-stop filter), you can effectively reduce the ambient light by three to six stops, allowing you to slow your shutter speed back down to the camera’s maximum flash sync speed (e.g., 1/200th second) while still shooting at a wide aperture like f/2.8.

• The Result: You regain the flash’s full power and achieve a much brighter, punchier key light with better background separation than HSS could provide.

2. Overpowering the Sun with More Wattage

If your goal is to completely overpower the sun and make the sky look dramatic, investing in a high-wattage battery-powered strobe (e.g., 400Ws or 600Ws) or using multiple lower powered flash/strobes is a better choice than using HSS on a low-power flash.

• By keeping your shutter speed at the maximum sync speed and dialing the strobe to full power, you can often achieve a clean separation and overpower the sun, which is difficult to do once the strobe is forced into the low-power pulsing of HSS.

Conclusion

While High-Speed Sync is a convenient feature for capturing a quick shot on the fly or when an ND filter is not available, it is fundamentally a compromised technique. For photographers who prioritize maximum flash power, consistent light quality, and extended battery life, avoiding HSS and utilizing Neutral Density filters is the superior and recommended approach that I might actually start doing in 2026.

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This has been Part 7 of a 12 part series for “12 Days Of Christmas 2025”. A collection of new articles and so much more from Mark G Adams from One Camera One Lens Photography as well as guest authors. Catch them all if you missed any here.