LENS FILTERS OR PHOTOSHOP...WHICH IS ETHICAL?
There is much to the debate of using software based exposure and tonal control, but how does it compare ethically to the use of age-old on-lens filters? While volumes have been written on this subject already, we will touch on the concept of filters vs. post processing alterations. The above image was shot RAW then Light Room applied knocking down the highlights to -77 creating a nice balance of highlights and shadows in a high contrast scene. A similar effect could have been achieved with a traditional graduated ND filter but at the cost of a break-line in the highlights.
The image below is an example of the same shot with an orange graduated filter (orange to show effect) and you can see how grossly overexposed the bottom right corner and highlights could be if pushed a half stop too open without a filter or adjustment in post. The warm filter failed, but it's a good example of how much contrast there was in a canyon scene like this and how easy it would be to blow out the highlights.
Does post-processing of highlights and contrast create an ethical dilemma compared to using “at-capture” lens filters? I personally do not think so if it's done in moderation and is used to replicate nature as it was when you stumbled across it. That opinion does not include altering colors to create unreal images such as purple sky’s or red water, but the digital medium has altered our ability to simply present the original film cast of old to the viewer and forces a photographer to compensate for the medium by using LR or other software editing tools. Filters and post processing can be abused and are both subject to the ethical expectations of photography. In the digital age, we are now subject to compensating for multiple manufactures idea of red or blue or any other color at capture and then compensating again for the multiple other pieces of equipment that must be used to reproduce our images before the consumer sees the end result. In the past there were only a few brands of film that dictated our tonal range for nature and landscape photography so tonal deviation was rare and post processing was not as common as it is now.
I am a strong opponent of HDR images (which is another entire topic for the articles page) and believe it should NOT be considered photography at all and replacing content in your image via software is even worse, but to make adjustments to your final product to represent the true colors of nature and vibrancy of a scene as shot, I think there is some leeway. Even in the days of film, labs would have slight tonal variations in the processing of Velvia for example and one lab may have a more magenta cast than another lab. So, when it comes to "punching" up an image...ethically if you add content, create an unreal representation of nature and replace colors with a filter, PS or LR...then you are not a purist and for the sake of the craft do not submit your images as "photography" and find another category to submit your work.
As for filters, like my pile of Cokin plastic squares, the above image with the orange grad filter is also an ethical pickle since it's radically altering the tone of the rock. Some of the old style filters were not much different than using LR or PS to change the color of a subject and were at the time considered unacceptable for professional use except for or ad work or intentionally artistic modernism.
If you compensate digitally for contrast and the shortcomings of the medium of reproduction then you are on the fair side of ethics and are not cheating the public into thinking you captured the one time in the history of planet that the ocean was purple at sunset and the second moon in your picture gave you a green glow on the mountain top. Remember, the "enhance" button on your iphone is not photography, it's a computer deciding what a programmer thinks is "cool". Your job as a photographer is to artistically represent nature in its purest form. Use the tools of the trade and learn exposure and how to capture life as it happens and you will always have images you can be proud of and say..."I shot that image"!