Know your flash's guide number at a glance

    If you aren't using your flash in automatic mode, you're going to need to figure out things like aperture and power levels on your own.

    But first you need to know how much power your flash has, and for that you need the guide number.

    The guide number is a figure that shows you the flash's power, based on a formual of distance times aperture. The higher the number, the farther away a subject can be and still illuminated adequately.

    In the old days, we would have to do some math to figure out the aperture setting for a subject at a particular distance, or use a table on the back of the flash that would tell you what settings to use for a subject at varying distances.

   Today, if you want to use your flash manually, there are calculators you can use on your phone, such as the one in the Photographer's Companion, where you input a few variables, such as the guide number, flash power and either aperture or distance, and it will do the rest of the work to find the right camera settings.

   If you don't know the flash number, you can look it up in the flash manual, which you can also upload to your phone so you'll have it at all times.

    If you have just one flash, remembering the guide number is simple enough. But what if you use more than one flash, and they have different guide numbers.

    What I have done is made a label showing the guide number that I affix to the side of each flash unit, so I can tell with a quick glance what the guide number is when figuring either how far away to put the flash, or what aperture I'm going to need to get the right look.

    When I made my labels, I used a word processing program and set it for an inverted output, with white numbers on a black background, making the label look inconspicuous, even more than the old tables that used to be on flash units.

Photographer's Companion a Swiss-Army-Knife app for serious shooters

    There are lots of apps on the market that can help with your photography.

    You can find apps that will turn your phone into a light meter, tell you when blue and golden hour are in your area and do a variety of functions.

    But if you have limited space on your phones (because companies will make it virtually impossible to delete some of the apps on your phone even if you'll never use them), you may find yourself picking and choosing which program to use.

    Or, you can just download one that can do most of the tasks you'll need.

    I would submit that the Photographer's Companion, available for both Android and iPhone, fits the bill nicely. Developed by Stef Software, it comes in free and paid versions, with the main difference being that the paid version has no ads and a few extra features.

    Personally, I've found the free version suits my needs, as most of the additional features in the paid version are things I wouldn't use or, in the case of flashlight and level, I already have on my phone or on my camera.

    

    For starters, this program gives you at the very minimum a reflected light meter. If your phone has a light sensor on it (this is usually used to adjust your screen brightness in relation to ambient light), you also get access to an incident light meter. This can come in handy when you're shooting manual or, as I did when I did a little photo project with my mother's old Argus C-3, the camera you're using doesn't have a light meter.

    You can also select your camera model or input the specifications, so it will be able to calculate things such as field of view and depth of field for your specific camera and lens combination. You can also use it to calculate proper flash settings, which is helpful in studio work or if you're using a non-dedicated flash on your camera.

    It can also show you when sunrise and sunset will occur in your area, as well as when to expect blue and golden hours, those times when light is at its most magical for photography. It can also show you the phase of the moon and the optimal exposure time for getting a picture of the moon or a moonlit scene.

    For those into astrophotography, it also uses the NPF rule for calculating the best exposure time to get no star trails.

    And each section has a help button that takes you to the website to get a tutorial on how to use that particular part of the app, as well as explain the principle behind it.

    This is not sponsored content, and I only use the free version, but I recommend it as a way to get some good high-quality photo apps without straining your phone's memory.