- Status
It depends on a few factors 
1) The size of the tube installed
2) How hard the tube is being pushed by the driver circuitry. ie: the discharge curve, charge voltage and current relative to the tube's max operating parameters.
3) How many full power flash cycles you use.
4) Mechanical considerations such as heat discharge etc.
Generally I replace tubes when the light output goes off my more than 1/2 stop from the baseline that I measure for the flash, or in the case of studio strobes when there's a noticable power decrease or change in colour temperature.
A quality flash like a Metz, Sunpak, Nikon, Canon or National should last many years of amateur use without the tube being replaced.
1) The size of the tube installed
2) How hard the tube is being pushed by the driver circuitry. ie: the discharge curve, charge voltage and current relative to the tube's max operating parameters.
3) How many full power flash cycles you use.
4) Mechanical considerations such as heat discharge etc.
Generally I replace tubes when the light output goes off my more than 1/2 stop from the baseline that I measure for the flash, or in the case of studio strobes when there's a noticable power decrease or change in colour temperature.
A quality flash like a Metz, Sunpak, Nikon, Canon or National should last many years of amateur use without the tube being replaced.
- Status