It might be good if I take a minute and go into some details about a camera’s flash system so people know why it can either enhance or ruin their photos.
Before I go into details let me explain that if you are taking photos of people (or a subject) who are less than twenty feet from you it is normally a good thing to leave your flash on. If you are taking any other type of photo chances are your flash needs to be off.
Have you ever taken a picture of Cinderella’s castle in low light to find out that you have a great picture of people nearby but the castle is not so good? This is a common flash mistake. You see it a lot. Every single sporting event, every showing of Wishes or Illuminations, or any nighttime display is loaded with a myriad of flashes. Almost none of these photos come out correctly.
When you enable your flash most cameras drop what is called the ISO level. To put it in simple terms the higher the ISO the less light you need to capture a photo. If the ISO didn’t drop with a flash everything captured would be insanely bright (that’s not a good thing).
You might wonder why you would want a flash at all if a higher ISO can be used. The higher the ISO level the higher the noise level. Noise is that grittiness that makes your photos ugly. So in theory you want the lowest ISO possible (the least noise is at 100).
I hope I haven’t lost anyone yet. When you kick on your flash your camera thinks your subject is close. That’s why it speeds up your ISO because it thinks the extra light from your flash is going to illuminate your subject. If you are taking a picture of Cinderella’s castle your flash is not going to reach that far so you would need to shut off your flash. When you shut it off your camera bases the settings it is going to use on the available light. In this case the light coming off of the castle. Your picture will be of a higher quality as long as there is enough light coming off of the castle.
How do you know if your subject is close enough to use a flash? There is a term for this. Every flash has what is called a “Guide Number” or “GN.” I’m not going to go into detail because the GN is based on a lot of factors but in really rough (and I mean rough) terms the GN normally means how far your flash will go. For example a GN of 25 typically means your flash will go up to 25 feet. If you bought your camera outside the states your GN might be measures in meters. If that’s the case remember to multiply it by about three to find out how many feet it will go. You can normally find out how far your flash will go in your user manual or online.
At this point I want to put a disclaimer in. Do not go online and but a new flash for your camera because it has a high GN. Like I said GN is based on a lot of factors. If you buy a flash based solely on GN you might as well throw your money away.
The bottom line is if you want to use your flash keep in mind how far it will go. If you subject is not in that range – turn it off!
Oh and as a side note – If you are on a dark ride or show your flash should NEVER be on. Beyond being insanely rude your pictures are not going to come out. You might wonder why. If you promise to NEVER do it I’ll tell you. The scenes in the Haunted Mansion, Pirates, or the Voyage of the little mermaid are perfectly lit. If you go busting out your flash you will never get the photo you want. You are going to get a crappy photo that you’ll most likely throw out later and you will annoy a bunch of people in the process.