As serious photographers, we are occasionally faced with shooting scenarios that we have less experience with compared to our usual subject choices. It can be helpful if we can test several setup scenarios before doing the actual shoot.
How large can we print, which lenses do we need, how much of the subject will be in critical focus? Those are just some of the questions we may want to be able and answer in advance, and go in prepared.
Many, if not all, of those questions can be answered with the use of so-called Depth of Field calculators. Several of those calculators are available on the internet, or as a dedicated application, also for smartphones and tablets. However, one of the biggest shortcomings of those calculators is that they require to input an important calculation parameter, the so-called Circle of Confusion diameter limit, but they do not offer any guidance as to what value is best to use
In fact, most of them offer preset values based on the selected camera model, thus totally ignoring the intended output quality requirements and viewing conditions. Producing large format output requires different settings than those required for producing images for a webpage. The one-size-fits-all approach doesn't fit at all if quality is your concern.
"It's a DoF calculator, Jim, but not as we know it."
The tool I am offering is a bit different. Of course it uses the same fundamental algorithms to calculate the physical consequences of lens settings such as focus distance and aperture, but it does so with our intended shooting goals and available equipment in mind. It also applies some automatic refinements, e.g. when diffraction is a limiting factor.
Therefore those shooting and viewing goals need to be determined as a first step, and the available equipment as the second, with a few simple selections. Only then will we be able to do meaningful calculations. The results of those calculations may occasionally surprise us because the calculated results are goal specific, instead of generic. That's particularly useful in uncommon shooting situations.
The tool will try and stay close to the input that was given earlier, if possible, therefore the order in which the input changes are made matters. Some of the choices will alter prior input, which is inevitable because everything is part of a single possible solution.
The fastest way to achieve the result we are looking for is to follow the sequential settings from top to bottom, that's why I've numbered them, unless one of the later parameters is already known to be a given.
An example is the choice of aperture / f-number, e.g. if the optimum lens performance is more important than the creative DoF consequences (e.g. in case of reproductions), then by all means select it first, and the rest of the parameters will follow this setting, unless the tool is forced by your
subsequent input to adjust the aperture again.
Another example is with Photomacrography, where it is often more logical to set the magnification factor first, and then move the subject into the focus-range. Then by all means, set the focal length of your macro lens, and the magnification factor first.
To simplify this first setup, I've provided a number of generic shooting setups that you can choose from with a pull down menu. Those settings will get you in-the-ball-park.
Now, without much further ado, here is the link to the on-line web application:The Depth of Field output quality planner
As of this posting, it's a beta-testing version release, although I've tried to already eliminate as many potential issues as possible. It was tested on several web-browsers, and I've also built in some prevention for overly 'creative' input, such as negative distances. Under very rare input situations, I hope, one may run into an issue. In that case pick one of the generic scenarios to get a fresh starting situation. Refreshing the web page will ultimately solve any issue, but also requires to redo all input from the beginning.
I welcome user feedback, it will help to make it an even more useful tool.