Beyond the obvious difference in size, only three significant features separate these models:

• The D-2000S does not have the built-in aiming light on the face of the strobe. On the D-2000, this light can be activated one of two ways:
  
  
  
  • Momentarily depress the switch to turn the light on for 8 seconds.
  • Depress and turn the switch in either direction to lock the light in the On position.
  
  This light will automatically quench as the strobe fires, so it does not affect your exposure.



• The D-2000S does not include External Auto mode.
• This mode is useful for any camera that allows manual exposure setting. In this mode the strobe's aperture setting is matched to the aperture setting of the camera via the right-hand dial on the strobe.
  
  
  
  The strobe then is dependent on the camera for the trigger signal only. Some INON models feature an electrical sync port, so this trigger signal may come via the optical fiber optic cable, or from the electrical sync cable. Either way, the External Auto functionality is the same.
  
  Once the INON strobe 'sees'  the trigger signal, it fires, utilizing reflected light from the subject to determine the proper duration of the flash. If necessary, you can fine-tune exposure by 'lying' to the strobe and setting a different aperture on the strobe than what is actually set on the camera.
  
  Because the light sensor (which reads the reflected light) is mounted in the face of the INON strobe, the strobe must be pointed directly at the subject for proper metering. Some models feature a built-in aiming light which helps determine proper aiming but should not be used as a focus light as that can induce backscatter into your images.
  
  



• The D-2000 utilizes twin flash tubes in a 'T' configuration, where the S-2000 relies on a single flash tube to do the heavy lifting. The result is a round beam pattern for the D-2000 and a more oblong pattern from the S-2000. In most instances the difference is negligible, but in some wide angle instances, the S-2000 needs to be oriented with the flash tube in a horizontal position for optimal light spread.