A Postmortem: Almost But Not Quite The Perfect Capture

Broken Top No Name Lake Nikon D850, Nikon 14-24mm f/2.8 @ 14mm, f/9, 1 second, ISO 200 - Image rendered here at: 2145 x 1426 at 300ppi

Few of us like to admit mistakes or failures. But I know my failures are learning experiences in disguise. To ignore an error would be to forfeit the opportunity to learn from it. 

This blog details errors I made that resulted in a missed opportunity to create a self-proclaimed portfolio level photograph. I openly share it with you in hopes you can learn from it and avoid the same mistakes.

Because my blog audience has a wide range of photography knowledge, skill, and experience, I’ve included both a quick read summary and a more in-depth version. The in-depth version includes not only the problem and remedies but also some tips and tricks. Whether you are a pro photographer or a photo enthusiast, I hope you find the information useful.

SUMMARY VERSION

Background

It was dark and cold. We arrived at Broken Top crater in time to consider a number of possible compositions. We stood at the exit point of No Name Lake. Our back was to the rising sun and Broken Top crater peaks were across the small lake in front of us. I found a composition I felt would portray the mood and story I hoped to tell with the photograph.

I worked quickly as the sunrise light was already beginning to illuminate the mountain peaks. 

The Gear

I was using a Nikon D850 full frame 45 megapixel camera with a Nikon14-24mm f/2.8 wide angle lens at 14mm’s on a Really Right Stuff TV-34 tripod with a BH-55 ball-head and a Nikon MC-36a shutter cable release. 

The image was taken just a couple of feet off the ground.

Exposure Settings

• Aperture: f/9

• Shutter speed: 1 second

• ISO: 200

The Problem

When I reviewed my files on the computer after the session, there were two big glaring problems. 

One, there were elements in the image that were out-of-focus. Either a foreground object, a background subject, or in some files, a combination of objects. In the image shown here you can clearly see the bottom right rock is out-of-focus. A 100% magnification also reveals that the mountain peaks are not in perfect focus.

100% magnification - left side of image - not sharp & corner skew & fall-off

The second big issue was frame corner softness (unsharp, not out-of-focus). At 100% magnification every corner had fall-off, unsharp pixels. It almost looks like the image is dripping off the corners. Of course at 14 mm you must expect a bit of this, but it is exaggerated in this photo and unsatisfactory to my eye.

100% magnification - bottom right corner out-of-focus with fall-off

Causes, Solutions & Lessons Learned

Problem #1: Out-of-Focus

I am obsessed with creating images with sharp focus. Over the years I’ve created a workflow to assure sharp focus images. So what went wrong?

One of three things happened to cause the out-of-focus problem. 

1. It could have been a poor hyperlocal calculation focus point on my part, or

2. Movement of the hardware (camera & tripod) after focusing or,

3. Inadvertently movement of the lens focus ring.

100% magnification - bottom of frame - sharp rocks but fall-off towards the corner

Solutions

After taking an image checking the focus is crucial. I use the + magnification tool. I start at the bottom of the frame and work my way to the top checking for in-focus sharpness. Then I check each corner of the image.

I did practice the above technique during this session. I did make sure the test frames were in focus from front to back. So the number one listed cause above is unlikely. 

Hardware or lens focus ring movement is more likely. It was dark, the tripod was on a bed of rocks with its feet under a few inches of water. I suppose I either bumped the tripod or camera or maybe bumped the lens focus ring groping for the cable release cord.

Lessons Learned

It is disappointing to find out an image you thought would be stellar turns out to be flawed. So next time I will;

1. Check the focus regularly even after it’s been confirmed during the test shot period.

2. Be more deliberate about moving around the tripod to prevent subtle movement.

Problem #2: Soft Image with Corner Falloff

There are a couple of things that can cause image softness or corner falloff. 

1. Poor quality lens glass &/or design - a problem seen mostly with less expensive lenses. Sharpness often improves with lens price.

2. Wrong aperture selection resulting in a short depth of field. I used an f/9 aperture. This lens has performed well in the past at capturing full depth of field at this f-stop. Besides, if this was the cause, softness would be seen across the entire image not just in the corners.

3. The camera and lens were not level to the horizon. A wide angle lens pointed up or down even slightly will distort subjects in the image - trees bending, building walls not at right angles, skewing, or corner fall-off.

Solutions

Experience with this Nikon 14-24mm lens tells me number one above is not the culprit. I do not know for sure what happen, but I am convinced at some point in the capture process the camera, tripod or both moved ever so slightly. 

Here’s some solutions to prevent this problem.

• Be sure you are choosing an aperture that provides full depth of field for the lens you’re using.

• When using a wide angle lens make sure the tripod and camera are perfectly flat to the horizon.

• If you think the tripod has been bumped or moved, start over. Re-level the gear and re-focus the lens.

• Finally inspect the image after the exposure. Specifically check to be sure subjects are not distorted and check the corners for fall-off.

The Long Version

This longer review version provides more context and some tips and tricks. So, for those who may have limited experience focusing in low light, are unfamiliar with terms and techniques like ‘hyperfocal distancing’, lens fall-off, etc. read on to learn more.

A Sharp Focus is Essential

The amount of predawn ambient light was minimal. Even good quality auto focus lenses have a tough time focusing in these ultra low light situations. Consequently I use manual focus most of the time. Here’s a few low light focusing tips and techniques to consider.

• If there is not enough light for the auto focus to work, switch the lens (or camera) to manual focus.

• Open your aperture to its widest (smallest number) when focusing. Wider aperture means more light and more light makes it easier for the camera to focus.

• Use a headlamp or flashlight to illuminate a focus spot.

• Use the + magnification feature on the camera to zoom in to the focus point.

• Once you have a sharp focus consider switching the lens to manual focus. If you don’t the camera will attempt to refocus each time you attempt to take an exposure requiring you to start the focus process over again.

• Learn what hyperlocal distancing is and how to calculate it (or look up) to identify the proper focus point. The technique is most useful when using a wide angle lens (wider than 35 mm).

I choose to use a hyperlocal distancing technique because there were foreground objects at the bottom of the frame and I was using a wide focal length of 14 mm. The hyperlocal distancing concept goes like this. If you’re using a wide angle lens there is specific calculated focal distance in feet and inches that will result in an image that is in sharp focus from your closest object to infinite.

There is a formula you can use to calculate the hyperlocal point. I use an app on my phone called PhotoPills. The app has a quick look up chart. It’s much quicker. The chosen lens focal length plus selected aperture are necessary to calculate the distance.

Alternatively you can use a focus stacking technique whereby you take multiple images without moving the camera focused at different points in the image. For example, you focus on an object at the bottom of the frame and take a shot. Then move the focus area to the mid ground and take another shot. Then to the background and take a third shot. Some newer cameras have a built-in focus stacking algorithm that automates the process.

This technique works well when there is enough light for your auto focus to capture a focus. However, if like me you are taking photos in very low light, you would need to manually focus each shot in the focus stack.

Appreciate that the second step of this technique is to blend these images together in editing process. Learning the editing process is the key to success.

One other caveat to consider. Understand that if anything in the frame is moving, tree branches, clouds, etc., the editing software will have a tough time bending the focus stack files.

The Composition

I composed the scene using the foreground rocks as stepping stones (leading line) into the frame. The camera was a few feet above the water’s surface on a tripod.

My vision of the final edit was to keep the foreground, up to the midpoint of the frame, dark. The morning sunrise light would take over from there to brighten the mountain peaks. The human eye would expect this transition. 

My focal length was wide to include the foreground rocks and incorporate the two triangle shaped peripheral hills in the frame. This would help force the eye to the center of the frame and up the mountain peaks.

The glacier water was clear and I planned to edit so that the shallow rocks would be visible in the final file. 

The sky had just a few visible stars in what was left of the civil twilight. I expected these would disappear as the sun rose and therefore wouldn’t likely be visible in the final file.

I exposed for the highlights knowing the snow at the base of the peaks would be void of detail if I overexposed the shot. I did want detail in the shadows but was willing to sacrifice them to assure the highlights were not ‘blown out’ (void of detail). Exposure bracketing was also a possibility.

Camera Leveling

A level lens is critical when using a wide focal length. Failure to do so will resulting in bending subjects and/or corner softness and fall-off.

I positioned and leveled the tripod and the camera. I use an integrated leveling base between my tripod legs and ball-head. So, I;

1. Leveled the tripod itself using the leveling base - centering the bubble level on the tripod platform.

2. Next I leveled the camera on the ball-head using the bubble level on the ball-head.

3. Then I turn on the horizontal level feature in my camera as a final check.

Exposure Process

Aperture and ISO were my exposure priorities. I choose an aperture of f/9 and an ISO of 200. This was the best combination given the low ambient light. The lake water was pretty still so the resulting 1 second exposure worked.

I took a number of test frames to confirm the best exposure setting. I examined the histogram after each shot and made the necessary minor adjustments.

My practice is to checked my focus after each test shot using the check steps described above. However, I did not check the focus once I established the test shots were in sharp focus. An error that likely caused the problem! Both my level and focus were not perfect.

So when I was done I thought I was walking away with a pretty special photograph, perhaps even a portfolio image. Unfortunately I did something that disrupted my workflow resulting in a poorly focused and unsharp image.

Food For Thought

Burn this into your photo-brain metadata. There is no software out there (yet) that can refocus a  file that is out-of-focus. You can sharpen an image but this does not fix an out-of-focus file! If the file is out-of-focus delete it. Or, create a folder titled Out-Of-Focus if you think software will be developed someday to correct this problem.

I hope this self-critique was useful. If you have thoughts or comments send them my way. I’d love to hear your feedback.

Thanks for your interest and support.

Cheers,

Steve