Monochrome Conversions

Over the past few days, I've been having a conversation in a photography forum about how to shoot monochrome images.  More specifically, someone had asked how to better utilize the in-camera color filters to get darkened skies.  

She was having difficulty seeing much of a difference between images shot without a filter and images shot with a filter.  It just so happens that I spent some time running some experiments pertaining to this topic a couple of years ago so I had quite a bit of useful advice.

This photographer explained that the skies were hazy and most of the scene was green foliage but that she could not see much of a difference between images shot without any in-camera color filters and those shot with a red in-camera filter.  Now she was wondering if she was doing something wrong or wondering if a true physical filter on the lens would be better.

I was the first in this forum to respond to her.  I explained that hazy conditions are lousy for getting darkened skies in monochrome.  Hazy gray skies are simply hazy gray skies.  I advised that she try to shoot monochrome when it was a clear day with bright blue skies and bright white clouds.  In these conditions, she would see a more significant difference in a darkened sky.

It just so happens that, on the following morning, I awoke to see the sky was clear and blue.  There weren't any big fluffy clouds but the sky was blue so I figured it might be a good time for me to capture some example images to share in this forum.  

The photo at right is a sequence of comparison images I shot.  I explained that all my basic settings were the same for each photo and that these are photos straight out of the camera without any editing other than resizing them for upload to the web.  The only thing I changed from image to image was the types of filters.  

The top image is a straight monochrome image with no filtering.  As you can see, the sky is light in this image.

I shot the second image with the in-camera red filter and the sky was noticeably darker.

For the third image, I added a polarizing filter on my lens but, again, shot with the in-camera red filter.  The sky was again considerably darker.  

For the fourth image, I went back to shooting straight monochrome (no in-camera filters, no polarizing filter) but added a 3 stop B+W 091 Red filter on the lens as though I was shooting with film rather than digital.  This is how we did it in the days of film (and how I still do it whenever I use one of my film cameras).  This red filter darkened the sky significantly but it also darkened the highlights through the entire image.

For the fifth image, I decided to use a physical filter that I knew would darken the skies almost completely.  I used a Hoya R72 filter which is a near-IR filter that cuts 10 stops of light.  I had to use a tripod for this shot because the filter cut so much light that my shutter speed needed to be open for a full second.  I also had to significantly increase my ISO.  This filter did exactly as I had expected though...  the sky was indeed dark while vegetation was light. 

So, I shared this comparison with the forum and we discussed the results.  Nobody in this group of photographers had thought of using an R72 filter for darkening the sky in monochrome so that opened up a whole new topic.  It was a "new topic" because this type of shooting is getting close to infrared imaging which is a whole different thing.  Our world looks completely different in infrared and the original question wasn't about physical filters nor infrared imaging.  Still I felt it was worth mentioning since the question was about effectively darkening the sky when shooting monochrome and anyone can screw one of these filters onto the front of their lens.

Here is a real quick and dirty explanation of wavelengths of light...

The light that humans can see is really only a relatively narrow band of light wavelengths compared to the full wavelengths of all light.  We can only see wavelengths between 400nm and 700nm.  This R72 filter is at 720nm.  Below 400nm is ultraviolet light, x-ray light, gamma ray light,   Above 700nm, we have near-IR, infrared, microwave, shortwaves, longwaves...  and really, visible light for humans is only a tiny sliver of all the wavelengths of light.  What we can see is really only a tiny sliver of light even when compared to even one of any of the other categories of light alone.  We truly are mostly blind to most of the universe.

The conversation on this photography forum then extended rather far into the weeds with geeky technical stuff related to sensors, sensor sensels, filter effectiveness and resolution.  At this point, I was beginning to be sorry for mentioning using this filter for darkening the skies in monochrome imaging.  We had strayed too far from the original topic related to the in-camera digital filters.  

In the end, a few photographers had decided they would purchase one of these filters and give it a go so that was good and I felt a bit better for mentioning the use of this filter for the stated purpose in this conversation.

Then I nudged the conversation back to how to get darkened skies when shooting monochrome which is in visible light.  

I explained that the best way I know how to accomplish this is to actually shoot in color and then develop the monochrome image in post-processing on your computer.  I explained how we did it in the darkroom when shooting with film and then explained how I do it digitally.  Naturally, I provided some example images, below...

I then explained how simple it is to darken the skies when using this technique of converting color images to monochrome while providing screenshots of how I do it.  Quite simply, you work with each group of colors individually..  red, orange, yellow, green, cyan, blue, purple, and magenta.  This allows you to control exactly how each color will be converted to monochrome and how we will see it in our monochrome image.  Consequently, each photographer's image will be unique.  

If we look at just one color, sometimes that one color will be a light monochrome tone.  Someone else may make that one color a dark monochrome tone.  Someone else may make that one color a medium monochrome tone or any tone from very light to very dark.  The same with each of the other seven color groups.  So, if you want darkened skies, darken the blue group and the cyan group. 

I also told them that if I could accomplish the same without the use of my computer, that would be great but it just doesn't happen in-camera like this...  not even close.  

We then discussed the topic of a loss in resolution when using the R72 deep red filter which is actually near-IR.  I explained that, yes, there is definitely a loss in resolution and a loss in bit depth but the images are still looking great, regardless.  Well, they will continue to look good as long as you don't try to push the processing too far.  

I then went back to the first set of comparison images to work on the R72 image again.  This is what I got...

To show the resolution of that image, above, I cropped a section of the above image, shown below at 100%.  In the cropped image, you can see that things are slightly fuzzy but this is really nit-picking because it is almost impossible to see when looking at the full image.  That image above appears crisp with great tonal qualities.  There is definitely a loss in resolution though...

Then, late last night, for my own purposes, I worked on two of my photos.

In this first one, below, I wanted to keep that barn as my subject and that is where I wanted to eye to go to when viewing this photograph.  At first, I processed the red in the barn to be a dark monochrome tone and the barn got lost in the dark trees behind it.  Then I processed the red in the barn to a light monochrome tone and it got lost in the vegetation between us and the barn.  I found that the best way to keep the barn more prominent in this particular monochrome image was to bring back some of the red.  I typically do not like selective color but, in this case, I'm liking it...

This photo, below, was shot on Lake Champlain during a cruise last summer (hmmm...  or the previous summer).  I love the clouds in this photo against the darkened sky (as well as in the photo above) but I really like the reflected light in the darkened water especially the reflected light bouncing off the big white sail.  That reflected light softly illuminating the dark tones of the water really captures your attention...

Incidentally, I have a camera that shoots in infrared light at a wavelength of 830nm.  This camera can capture stunningly crisp monochrome images.  The visible light monochrome images in this blog entry are really nice and crisp too though!