sCMOS and EMCCD cameras are the two main types of scientific camera used in fluorescence microscopy. EMCCD cameras amplify the signal before readout, giving them the edge when only a handful of photons reach each pixel. sCMOS cameras combine low read noise with large sensors and high frame rates, which has made them the default for most modern microscopy, including light sheet microscopy. This article compares the two and explains how to choose.
How each camera works
EMCCD: electron-multiplying CCD
An EMCCD is a CCD sensor with an extra gain register. Before the signal is read out, the charge from each pixel passes through hundreds of multiplication stages that amplify it many times over. Because the signal is boosted before the noisy readout step, read noise becomes effectively negligible, and the camera can detect single photons. The cost is an excess noise factor from the random multiplication process, and generally smaller sensors and lower frame rates.
sCMOS: scientific CMOS
An sCMOS sensor has an amplifier and converter for every pixel or column, so millions of pixels can be read out in parallel. That gives high frame rates on large sensors with very low read noise, typically around one to two electrons. There is no multiplication gain, so there is no excess noise, but read noise sets the floor in the dimmest conditions.
sCMOS vs EMCCD compared
| sCMOS | EMCCD | |
|---|---|---|
| Read noise | Very low (about 1–2 e⁻) | Effectively below 1 e⁻ with EM gain |
| Excess noise | None | Multiplication adds an excess noise factor of about √2 |
| Sensor size | Large, often 2048 × 2048 pixels or more | Smaller, often 512 × 512 or 1024 × 1024 |
| Frame rate | High, tens to hundreds of full frames per second | Lower at full frame |
| Dynamic range | Wide | Narrower at high gain |
| Best signal level | Moderate to bright, and most live imaging | Extremely low light, a few photons per pixel |
| Shutter | Rolling, global or both | Frame transfer |
Which camera for which microscope?
- Light sheet microscopy: sCMOS. Large sensors and high speed match the wide field and fast volumetric imaging, and rolling shutter readout can be synchronized with a scanned sheet.
- Spinning disk confocal: usually sCMOS; EMCCD where signal is very weak.
- Single-molecule and super-resolution: both are used; EMCCD for the faintest emitters, sCMOS where field of view and speed matter more.
- Widefield fluorescence: sCMOS in most cases.
- Photon counting and extreme low light: EMCCD.
Rolling shutter and light sheet readout
Many sCMOS cameras read the sensor row by row in a rolling shutter. In a scanned light sheet microscope, that readout can be synchronized with the beam as it sweeps across the field, so each row only collects light while the sheet is passing over it. The rolling readout then acts like a moving slit, rejecting scattered light and improving contrast. Getting this right depends on precise timing between the camera, the galvo scanner and the laser. See microscope hardware synchronization.
Other factors when choosing a scientific camera
- Quantum efficiency at your emission wavelengths; back-illuminated sensors reach over 90% in the visible
- Pixel size relative to the microscope’s resolution and magnification
- Data interface and sustained frame rate; full-speed sCMOS output can exceed what standard interfaces and disks handle
- Cooling and dark current for long exposures
- Triggering modes and timing outputs for synchronization with other hardware
- Software support for your acquisition platform
Sciotex has integrated both EMCCD and sCMOS cameras into custom microscopes, including multi-camera systems. See Sciotex’s custom microscope software services.
Frequently asked questions
An EMCCD amplifies the signal before readout, making read noise negligible and enabling single-photon detection, but adds excess noise and usually has a smaller, slower sensor. An sCMOS reads pixels in parallel with very low read noise, giving large sensors and high frame rates.
For most fluorescence microscopy, including light sheet and widefield imaging, sCMOS is the better choice because of its speed, field of view and dynamic range. EMCCD still wins when only a few photons reach each pixel.
sCMOS cameras are standard for light sheet microscopy because their large sensors and high frame rates suit fast volumetric imaging, and their rolling shutter can be synchronized with a scanned light sheet.
Electron-multiplying charge-coupled device: a CCD sensor with a gain register that amplifies the signal before it is read out.
Related articles
- Light Sheet Microscopy: How It Works, Types and Instrument Control
- Lattice Light-Sheet Microscopy: How It Works and Where It Fits
- Adaptive Optics Microscopy: Correcting Aberrations in Deep Tissue
- Microscope Hardware Synchronization: Galvos, Piezos, Lasers and Cameras
- Laboratory Automation Software: Custom vs Off-the-Shelf
