Jim Chapple is now working full time on iphone/ipod touch and iPad applications.
Jim Chapple also works on Mac OS X Apps.
Please email Jim Chapple for support issues, information and quotes.
Ever taken a picture and wished that either more of it had been in focus or the exact reverse and that less had been in focus? Of course you have I certainly have. But what settings on your camera give which results and what if you change one of those settings what is the Depth of Field then. You can calculate it all yourself but it is not easy. This App takes all of those problems and makes it easy to find the answers. Just type in the distance to the subject, the focal length being used and the f-stop and the App calculates the near and far distances of acceptable focus and therefore the depth of field. This is all shown on an easy to understand diagram.
An example is: You are trying to take a photo of a bee on a flower and all but the bee is to be out of focus. Set the distance of the subject to be 200 mm (20 cm, approx 8 inches), set the f-stop to be f/5.6 and set the focal length at 50 mm. The App calculates that the depth of field is 3.41 mm (0.3 cm, a small fraction of an inch). The bee will be partially in focus but bees are more than 3.4 mm across so that depth of field is probably not what you were looking for. Set the camera to f/22 and now the depth of field is 13.39 mm (1.39 cm or just over half an inch) now this is much closer to what you wanted. Now maybe the whole of bee is in focus but still all of its surroundings are out of focus.
The small thumbnail images below will show larger iPad screenshots.
FAQ: This App does not work properly it keeps on crashing, why?
Sometimes Apps just do not download properly. You will need to download it again, for free, using itunes. See Apple Support Pages
About half way down the page there's a set of instructions that starts 'Reinstall the affected application'. Once iTunes has it then you sync your device and it should then work. If it does not then please to contact me.
When the Application Starts
The App initialises itself to read all the last settings used and the selected camera. Obviously the first time it starts there are no saved items so it defaults to some reasonable values.
At the top of the screen the camera button takes you to the camera page where you can select the camera you are using. It is important you do this when you first start because the calculations use a value called the cirlce of confusion. It's value is determine by the make and model of the camera being used.
Once the camera has been selected you can use the App to generate the depth of field for the settings you are using and the distance to the subject.
A keypad is used to enter all of the required values giving you complete control over the values you are setting.
Enter the distance to the subject, select the units for that distance (metres, millimetres, feet or inches), enter the f/stop value and enter the focal length being used. To enter the values just select the field and then enter the number required using the keyboard. Either press the field again to dismiss the keyboard or select OK.
Once all values have been entered then the diagram will change to show the hyperfocal distance, the near distance and the far distance and the calculated depth of field.
You can see any of the distances on the diagram in alternate formats by touching the screen where the amount is shown. This will show an alert with the distance specified in its alternate form.
The Camera Page
On this page are two different ways to set the circle of confusion value. Either select the make and model of the camera in use using the picker wheels OR specify the circle of confusion value using the field at the top.
Generally, it is best to select the make and model of the camera and use the known circle of confusion for the camera.
Alternatively, you may just want to specify the value you want to use. If this is so then enter the value in the field above using the number keyboard. This value always overrides any make and model of camera selected below.
Main Page - Infinite/Infinity
It is quite possible for the far distance value to be calculated as infinity and so the depth of field is infinite. The near distance will still have a value.
The far distance will be infinite if the distance to the subject is greater than the calculated hyperfocal distance.
Main Page - Zero depth of field
It is quite possible for the the near and far distances to be set to the distance to the subject and the depth of field is zero.
This occurs where the distance to the subject is less than the focal length of the camera.