Welcome to FlashApp!

FlashApp is a lightweight, easy to use Android app for calculating Guide Numbers.

As someone who does a lot of photography I found myself in need of something I could use to do calculations on the move. A lot of new digital cameras have this built in, but I'm a big fan of old film cameras which obviously don't have this functionality. That's why I decided to make FlashApp.

What is a Guide Number?

A guide number is a number assigned to your flash unit which tells you how powerful it is. By using this, the ISO of your film, the aperture of your camera and the distance you are standing from your subject it is possible to calculate camera settings in order to perfectly expose your picture.

This app lets you enter the settings from your flash and camera in order to tell you how far away to stand or enter the distance you want to stand and tell you what settings to use on your camera.

How to use the App?

The app should be fairly easy to use. There are six different settings you can enter: Guide Number, ISO, Power, Aperture, Distance and the unit for Distance. The settings that can be calculated are the aperture and the distance.

Guide Number: This should be found either on your flash itself or in the operating manual.

ISO: This will be written on your film canister.

Power: Your camera flash will have the option to increase or decrease the power on your flash by fractions. When you use this functionality make sure to adjust for it in FlashApp.

Aperture: This is the setting on your camera. You should be able to change it by hand on the lens or using the electronic settings on your camera.

Distance: How far away you need to stand from your subject.

To calculate the aperture enter the Guide Number, ISO, Power and Distance (including units) and hit the 'Calculate Aperture' button. The aperture field will then populate with the raw aperture number that will best expose your photo. Set your camera to use the closest available aperture for best results in your photos.

To calculate the distance enter the Guide Number, ISO, Power, Aperture and Distance Units and hit the 'Calculate Distance' button. The distance field will then populate with the distance (in whatever units you chose) from the subject you will obtain the best results.

Complaints, Compliments and Suggestions

If you have anything to say (be nice please) then feel free to send me an email at [email protected]!