Photography 101

A Beginner’s Guide to
Flash Photography
Power Management of Your Flash
(Part 43)–

In our past three issues (Photography 101 December 22, 2009, January 5, 2010, and January 19, 2010), I have discussed the fundamental theories and some basic information about the powerhouse of electronic flash – the battery. To continue our discussion, I will answer a timely question from our INBOX.

 

From Maya Avila of Cavite City

 

Dear Mr. Rivera,

 

Dear Maya,

Your query is a timely topic, therefore I can answer you with an elaborate explanation.

 

On which type of Battery

There are two popular AA battery types currently available in the market today: The nickel cadmium (NiCad) and the newer one called nickel Metal Hydride (NiMH). Both cells have the same voltage of 1.2 volts when fully charged. The NiMH has the advantage over the NiCad because it is available in high capacity (as high as 2900maH in a single cell). It is also very light in weight and environmentally friendly to dispose of when dead. And because the NiCad has been around for quite a long time, its qualities and attributes have already been known and covered in many publications. That explains why this chapter mainly covers the newer type battery – the NiMH.

It is likely that you will prefer to buy the NiMH type because the price is nearly the same as the NiCad. Also, you can get the higher capacity cell in terms of maH. The higher NiMH capacity cell (typical 2000 to 2900 maH per cell) provides more flashes per charge.

I have read two of your articles last month (Part 41 and 42) and learned so much from them. We are a group of mostly beginners in photography and not yet technically oriented. We plan to buy a flash and of course, battery and charger. As there are many kinds (and brands) of battery in the market, what can you advise us?

 

In terms of performance with respect to flash recycling time, both types of battery are at par in performance. The trade-off, however, is that the high capacity NiMH takes a longer time to charge. (See table, Photography 101, Jan. 19, 2010 issue)

 

On what type of charger

Use Overnight Charger because it is good for starters. Most hobbyists shoot on pre-scheduled dates (normally weekends). This means that you have the luxury of time to charge your battery unlike professional photographers where they must be ready to shoot in a few hours notice; you don’t really need a fast charger as a professional requires it. The advantage of using a slow charger may be summarized as follows:

• Economy. Slow Charger or Overnight Charger is the cheapest one you can buy. This is because of its simplicity of product design and low in electronic parts count.

• Comfortable to Use. Once the number of charging hours is already known to you, you can plug it when you arrive home, retrieve it tomorrow without worry of overcharging because of the low charge rate of this type of charger.

• Gentle to your Batteries. NiMH and NiCad batteries are known to have longer life with overnight chargers because they do not get hot during charging. When AA battery becomes extremely hot due to overcharging (occasionally happens in fast charging), safety vents inside the cell opens. This prevents pressure build-up inside the cell that may cause explosion. Gases that are part of the battery chemistry escape from the cell body, thus reducing its life.

 

Concerns in buying Overnight Charger

The first to note when buying an overnight charger is the total number of charging hours for your battery. Charging hours are determined by charge rate (in mili-ampere current) of the charger and the capacity (in mili AmpereHOUR) of your AA battery. If this is too complicated for you, the store’s technical staff should be able to tell you the recommended charging hours. In this respect, it is advisable to simultaneously buy your choice of battery to determine the correct charging hours. Some branded AA batteries are often sold in packaged with a charger. You may also refer to Part 42 (Jan. 19, 2010 issue of Photography 101) if you prefer to determine yourself the total charging hours. Failure to know the correct charging hours will likely lead to undercharging of your battery.