The other day some of us got into a discussion regarding the ethics around the treat of a moon within an image, particularly around sunrise and sunset during a full moon. including the moon within an image involves two challenges, its brightness and its size.
The brightness of the moon: Most good digital cameras today have a dynamic range of approximately 14 stops of light whereas humans can discern 24 stops of light. So what do we mean be this? Essentially the concept of dynamic range applies to the spread of darkness to brightness that that can be recognized. In a digital camera that is the brightness that has not gone totally white with no more detail and the same for the black are, there is still data there. An excellent web site for all things technical regarding photography is Cambridge in Color and they have an excellent discussion of dynamic range here. So think about this, the human visual system can “see” almost twice as brightness and darkness then the best digital cameras today. That is pretty impressive.
Now, there are only limited times during the day when the moon is within the cameras dynamic range in relationship to the surrounding scenery. However, as mentioned above our visual system is able to discern the moons surface in the dark as well as during the day much better than our camera. So the first issue is what is more right, to present the moon as we humans perceive it or to let the camera overexpose the moon and leave it as a bright blob? During film photography, a lot of good photographers would double expose the scene, once for the bright lights and another for the background. There is no a similar option in digital photography other taking two exposures and blending them together. Generally speaking, this is the approach I take and I feel compelled to take both images at the time I am shooting. I also find that I do a lot of High Dynamic Range (HDR) shooting to help compensate the shadows and the bright spots. Again, from Cambridge in Color, a discussion of how HDR Photography works.
To further complicate this discussion, film had an algorithmic curve bent at both the high and low ends which allowed film to better handle bright lights at the high end and not be so unforgiving of the shadows.
So had I been shooting film this morning I may have had a better chance of not over exposing the moon. This is in contrast to a digital camera which has a linear curve. So, even in the use of photography equipment, one can get different results.
A linear image basically means that one photon is recorded and one number is incremented as the brightness of the image increases. Double the number of photons and you double the brightness in the image. It is actually much more complicated than that, but that is a very basic explanation. All digital sensors record light in a linear manner in the raw file.
So, to end this discussion on brightness, is it more correct to display the moon as a bright blob with no characteristics because our present day technology cannot capture what our eyes can see, or is it more correct to represent the moon the way humans can see it, which involves multiple images blended together like the image displayed at the top of this post.
The focal length of the lens. The focal length of the lens. It is the common understanding that our eyes perceive the world around us at about the equivalent of 50mm. So if I were to use a 50mm lens for all of my images, they would all look to be approximately the same physical size as I saw them. However, this restricts a photographers ability to capture a wider “field of view” than what we can see. If I chose to use a lens with a smaller focal length, (the distance between the cameras sensor and end of the lens), something less than 50mm, this will make distant items smaller than our eye perceives them. Conversely, if I chose to use a lens with a focal length larger than 50mm, it will have an increasingly smaller field of view and make items in the distance look larger relative to closer items. (Understanding Camera lenses)
So if I take a picture with a 34mm as I did in the image above the moon will be smaller than what we visually see in relationship to the items close at hand. So this is our second quandary, is what is more right to slightly expand the moon to more represent what we visually see or to leave the moon smaller and bright as my equipment capture it below? This is really an important question because the moon is in almost all cases an important ingredient in the images composition.
The discussion of the moon becomes even more complex when people take artistic license and make the moon way larger than it actually is and in those cases, I don’t think there needs to be a disclosure since it is quite obvious what is going on. Here is an example of how I was able to make the moon in the scene larger than it would normally be with the use of a 200mm lens. Am I obliged to make an adjustment to make it smaller?
But I think this topic of ethics reaches a grayer area when photographers make items in the distance larger because of the focal length being used to capture the general scenery. distorts the size of distant items. I am guilty of doing this only occasionally, but it does happen. A very common Seattle view is a shot taken from the top of Queen Ann Hill of the Seattle skyline and with Mt. Rainier in the distance. Here are a couple of some old Seattle Skyline images, the first with Mr. Rainier enlarged and the second the actual one. Most of the images taken from here are of the former variety.