If your EMCCD camera doesn’t seem quite as sensitive as it used to be, you’re not imagining things. Over time, every EMCCD naturally loses some of its ability to amplify faint signals — a process known as gain aging. It’s a completely normal part of EMCCD life, but it does affect how your camera performs in the long run.
The Power — and the Problem — Behind EM Gain
One of the reasons EMCCDs became legendary in low-light imaging is their ability to see what other sensors can’t. Inside each EMCCD is a multiplication register — a clever section of the sensor that boosts weak signals before readout.
Here’s what that means in numbers:
A typical EMCCD might start with a read noise of 75 electrons. Apply a gain of 300×, and that noise drops to:
75/30 =0.25 electrons
That’s incredibly low — essentially at the theoretical noise floor, allowing you to detect even single photons.
But here’s the catch: that 300× gain setting doesn’t stay the same forever. As the camera is used, that 300× might quietly drift down to 290×… then 250×… then 200×. So while the software might still say “Gain = 300,” the sensor inside isn’t actually multiplying by that much anymore.
The result? Your effective read noise goes back up, and your low-light performance slowly fades.
Why EMCCDs Lose Gain Over Time
The reason comes down to physics. The EM gain process works by applying very high voltages inside the chip to create electron multiplication through impact ionization. Over time, those powerful electric fields cause tiny, permanent changes in the silicon structure. It’s a bit like wear and tear — every time you run your camera at high gain, it ages a little faster.
The higher the gain, the warmer the operating temperature, and the longer the camera runs, the quicker this effect builds up. Eventually, even recalibration can’t fully restore the original performance.
Recalibration: A Temporary Reset
The good news is that you can often recalibrate your EMCCD’s gain to bring it back into alignment. Some cameras can even do this automatically, adjusting internal voltages to restore your target gain (like resetting 290× back up to 300×).
And if you need a more complete refresh, many manufacturers can recalibrate your camera in the factory, extending its useful life. However, every EMCCD eventually reaches a point where it runs out of headroom — when the multiplication register simply can’t deliver the same amplification anymore.
Enter the New Era: sCMOS
This gradual aging is one of the main reasons the industry has shifted toward scientific CMOS (sCMOS) technology. sCMOS sensors achieve exceptional low-light performance without the drawbacks of EM gain — no high-voltage stress, no aging, and no recalibration needed.
And now, with the arrival of advanced sensors like the Aries 6504, the difference is striking. The Aries delivers read noise as low as 0.43 electrons rms — approaching EMCCD-level sensitivity — but with higher frame rates, larger sensor formats, and complete long-term stability.
No gain to adjust. No aging to worry about. Just consistent, ultra-sensitive imaging performance from day one to year five.
The Takeaway
Your EMCCD camera hasn’t failed — it’s just getting older. That’s the nature of electron multiplication. But for many applications, the move to modern sCMOS cameras like the Aries 6504 offers the best of both worlds: near-zero read noise, faster speeds, and a sensor that never loses its edge.
If your EMCCD is showing its age, it might be time to experience the next generation of low-light imaging sCMOS— where sensitivity, stability, and simplicity all come standard.