cowasaki
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Is it safe to use my old flash?
I have seen this question come up numerous times so I thought I would do a mini tutorial.
The history and theory
Back in the time on film cameras most flashes were simple devices which explains why they were so cheap in comparison to modern flash systems such as an SB600. Basically you had a power source (usually a couple of AA batteries) which charged up one or more capacitors. This took a few moments in which time you often heard a wining noise and then once the capacitors were fully charged a small light would illuminate. In order for the camera to make the flash light all it had to do was complete a simple circuit at which point the voltage stored in the capacitor was discharged into the flash bulb. On these models you will see a voltage (trigger voltage) of typically 250V DC.
On some flashes (and all modern ones) the two contact points are not actually connected directly to the capacity but short it via a relay, transistor or similar. On these models you will see a voltage (trigger voltage) of typically 6V DC.
The circuit is complete once two small connectors are shorted out on the flash. These are the CENTRE PIN and the HOTSHOE GROUNDING POINT. These can be seen in this diagram:
Now that is the HOW THEY WORK question sorted but what YOU want to know is "Can I use my grandad's old flash gun on my sparkly new D3?". This is a question that we need several variables to answer.
This first thing we need to know is "What is the trigger voltage of my flash?".
Well you can often look these up the internet but the problem with this is that anyone can put things on the internet and anyone can make a mistake. You would not be happy connecting an old flash up that you read uses 6V only to find it was 256V and you now need a new DSLR!!
Don't worry it is very simple, what we need to do is place new batteries into our flash and switch it ON. Once it is fully charged we connect a multimeter across the two contact pins and read the DC voltage.
Right now with the probes connected to the pins (it does not matter which way round they are as we will ignore the sign in the result) we can read the trigger voltage off the multimeter's display.
This is the result for MY Praktica 1600A flash.
We can see this again doing the same to the other flash.
As can be seen, the Vivitar 16A Auto gives a different voltage.
This second thing we need to know is "What is the safe voltage for my camera?".
Right well this is something you will need to check in your manual.
The voltage of my flash is too high for the camera, is there anything I can do.
YES. There are devices that you can plug into your camera's hotshoe and attach the flash to. They are the equivalent of the extra level of circuitry that modern flashes have and are acting like a relay does with the spot lights on your car!
I have four extra posts below that I will update with the information when other TPers give me their figures! I thought that this would help us avoid answering the same question over and over again.
WARNING: As always with hardware tutorials, follow this tutorial at your own risk. I might have no idea what I am talking about
I will not be responsible if you blow up your Nikon D3x using a £12 Sunpak flash.
Hope people like the idea.
I have seen this question come up numerous times so I thought I would do a mini tutorial.
The history and theory
Back in the time on film cameras most flashes were simple devices which explains why they were so cheap in comparison to modern flash systems such as an SB600. Basically you had a power source (usually a couple of AA batteries) which charged up one or more capacitors. This took a few moments in which time you often heard a wining noise and then once the capacitors were fully charged a small light would illuminate. In order for the camera to make the flash light all it had to do was complete a simple circuit at which point the voltage stored in the capacitor was discharged into the flash bulb. On these models you will see a voltage (trigger voltage) of typically 250V DC.
On some flashes (and all modern ones) the two contact points are not actually connected directly to the capacity but short it via a relay, transistor or similar. On these models you will see a voltage (trigger voltage) of typically 6V DC.
The circuit is complete once two small connectors are shorted out on the flash. These are the CENTRE PIN and the HOTSHOE GROUNDING POINT. These can be seen in this diagram:
Now that is the HOW THEY WORK question sorted but what YOU want to know is "Can I use my grandad's old flash gun on my sparkly new D3?". This is a question that we need several variables to answer.
This first thing we need to know is "What is the trigger voltage of my flash?".
Well you can often look these up the internet but the problem with this is that anyone can put things on the internet and anyone can make a mistake. You would not be happy connecting an old flash up that you read uses 6V only to find it was 256V and you now need a new DSLR!!
Don't worry it is very simple, what we need to do is place new batteries into our flash and switch it ON. Once it is fully charged we connect a multimeter across the two contact pins and read the DC voltage.
Right now with the probes connected to the pins (it does not matter which way round they are as we will ignore the sign in the result) we can read the trigger voltage off the multimeter's display.
This is the result for MY Praktica 1600A flash.
We can see this again doing the same to the other flash.
As can be seen, the Vivitar 16A Auto gives a different voltage.
This second thing we need to know is "What is the safe voltage for my camera?".
Right well this is something you will need to check in your manual.
The voltage of my flash is too high for the camera, is there anything I can do.
YES. There are devices that you can plug into your camera's hotshoe and attach the flash to. They are the equivalent of the extra level of circuitry that modern flashes have and are acting like a relay does with the spot lights on your car!
I have four extra posts below that I will update with the information when other TPers give me their figures! I thought that this would help us avoid answering the same question over and over again.
WARNING: As always with hardware tutorials, follow this tutorial at your own risk. I might have no idea what I am talking about
I will not be responsible if you blow up your Nikon D3x using a £12 Sunpak flash.Hope people like the idea.
