Depth of Field & Exposure Calc

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.

This App will help you take much better photographs by being able to understand the relationship between the settings on your camera and the depth of field that they produce. The diagram shown is better than a thousand words of text (as the saying goes). You can now easily see what effect a change in the settings will make.

The Depth of Field Calculator allows you to quickly calculate the near and far distances of acceptable focus. Just select the distance you are focused at, the f/stop and the len's focal length and the diagram shows you at what distance acceptable focus starts and at what distance it ends. You can select to express the focus distance in metres, millimetres, feet and inches. Unlike other Apps this App does not use picker wheels for the f/stop and focal length values so you can enter whatever values you want.

It is important to select the maker and model of camera you are using otherwise the calculations are not likely to be correct. If you camera is not listed then email me and I will add it to the next release.

The other main problem this App handles is what shutter speed will be required given the lighting conditions, the f/stop used and the iso rating of the film. Once again it can all be hand calculated and looked up on lighting tables that are available but this is not easy and the tables do not have all values listed that are possible.

The Exposure Tab takes the f/stop and iso rating and in combination with the your assessment of the lighting conditions provides both an exact answer but also the generalised table for the settings and conditions.

The exact answer can be the same as the answer in the table but can also be somewhere between one answer and the next. This is because the standard tables do not list every f/stop that is possible nor is the effect of the iso rating always easy to work out.

The answer given is very precise and you may find you cannot set your camera to this value. This is not a problem because the whole assessment of the lighting conditions is very subjective. The answers given are meant to be a guide. You may wish to take a number of shots around the shutter speed given.