The post Photo Mistakes? Learning from a “Photo Autopsy” appeared first on Digital Photography School. It was authored by Rick Ohnsman.
Sometimes things just don’t work out, you make photo mistakes and your resulting image is DOA – Dead on Arrival. What went wrong? To borrow terminology from the world of forensics, determining the “cause of death” might require a “photo autopsy.” A session using investigational tools and procedural techniques can reveal the fatal factors involved. You would hope to learn how to prevent such photo mistakes in the future. You might also sometimes discover that the image may not be dead after all, but only wounded with the opportunity for recovery.
What Photo mistakes killed your photo? Learn some photo forensic techniques to discover what happened.
I hope you will not find my use of these terms overly morbid. I use these analogies because they lend themselves well to the methods of discovering what may have gone wrong with your image.
In criminal investigations, it is a forensic pathologist who would perform an autopsy. Using medical knowledge, training and skills, they hope to gain insights that might assist criminal investigators and ultimately provide evidence such that a jury can render a verdict.
So let’s learn about some tools and techniques to solve the crime that is a bad photo.
Physical examination
You make a shot, chimp your image on the LCD, and doh! You see that you blew it. The photo is bad.
Other times, you don’t discover you’ve made serious photo mistakes until you see your images in an edit session. That’s why they made the Delete button, right? Just make those mistakes go away.
But wait…
Might taking some time to investigate the “cause of death” teach you something?
Failing to understand and learn from your mistakes is a sure way to repeat them. Learning how not to make photo mistakes is the key to becoming a better photographer.
Don’t be so quick to hit the Delete Button. Learning what happened can teach you a lot.
So, as a forensic pathologist might do, take some time to look at the “victim.” What do you see? Is there anything that doesn’t look right? What does a visual examination of your bad photo show you? Chances are, bad photos will have one, or sometimes both, of these things wrong:
- The photo is poorly exposed
- The photo isn’t sharp where you want it to be
Let’s explore those two things a bit more.
Bad exposure
How do we define “bad exposure?” One way is the simple visual examination.
Are the tones in the photo rendered such that we can see some detail in both the brightest and darkest parts of the image? Are the highlights “blown out” with no detail or the shadows “blocked up,” also with no detail? Does the image “feel” too dark or too light? Is it rendered how you want it to look?
The more scientific “forensic way” of determining whether an image is exposed correctly is learning to use a histogram.
I won’t spend time discussing the fine details of this tool, as there are many good articles here on DPS that do that. Briefly, a histogram is a bar graph of the 256 shades of luminance (brightness), in your photo from total black on the left (RGB 0,0,0), to total white on the right (RGB 255,255,255).
The highlighted photo is underexposed. Visual examination tells you that and the histogram confirms it.
To borrow a football analogy, an image that is “between the goalposts,” that is, not smashed up against either side of the histogram, is a completely editable image. While that may not mean it was “properly exposed” in the camera (it still could be too light or dark and need editing), both the darks and lights have details you can recover.
The caveat here is that you shot in Raw mode. Adjusting exposure in edit, bringing up the darks, bringing down the lights, redistributing the tones works quite nicely with a Raw image. A JPG…not so much.
The extremes of dynamic range, from deep shadows to bring sunlight, make this a tough photo to expose correctly. You can use the Shadow and Highlight Clipping indicators in Lightroom to see what’s clipped. The blue areas are totally black (0,0,0) and the red areas are totally white (255,255,255). No details can be recovered in these spots.
Internal examination – learning to use EXIF data
To really understand the factors that created an exposure, and why it might not have turned out as we hoped, we will need to go further with our “photo autopsy” and get inside.
As you likely know, three factors control exposure: Aperture, Shutter Speed, and ISO.
In the film days, photographers had to make written notes if they wanted to recall exposure settings for an image. With digital cameras, you can find that information stored in the image file using what is called EXIF (EXchangeable Image File) data.
Viewing EXIF data
The camera writes the EXIF data. It contains a wealth of information about the image; the date and time you shot the image, the camera make and model, the lens used, whether you used a flash, all kinds of exposure data, and if the camera has GPS capabilities, the specific spot you took your photo.
Also called “metadata,” think of this information as extensive notes about the photo.
If you’re trying to understand why your image isn’t exposed as it should be, the ability to see exposure settings – specifically Aperture, Shutter Speed, and ISO – can be very insightful.
If your camera records GPS coordinates to the EXIF file (one advantage to cellphones – most do), you can use Lightroom to find the specific spot on a map where the photo was taken. I want to get back to this great aspen grove in the Sawtooth Mountains of Idaho again… it was spectacular in autumn.
So how do you see this information?
Most good photo editors allow you to view EXIF information. The means of invoking this command and how much data is shown may vary depending on the program.
Let’s take a look at how a favorite program of mine, and one I recently wrote about, Irfanview displays EXIF information.
Looking at the photo below (IMG_3845), straight out of the camera without editing, it visually looks like the image was underexposed. It’s too dark, and a look at the histogram confirms this.
Using Irfanview to show the EXIF data, here is just some of the data recorded (I’ve extracted just the useful data for our discussion).
You can see visually this is underexposed. Now, what does the EXIF data tell you?
Filename – IMG_3845.CR2
Make – Canon
Model – Canon EOS 6D
ExposureTime – 1/500 seconds
FNumber – 4
ExposureProgram – Manual control
ISOSpeedRatings – 1600
MeteringMode – Spot
Flash – Flash not fired
Lens Model – EF24-105mm f/4L IS USM
Quality – RAW
Flash mode – Not fired
Focus mode – AI Servo
White Balance – Tungsten
Irfanview gives very comprehensive EXIF data results.
Here is the EXIF data for the same photo as displayed by Lightroom.
The same photo with EXIF data as displayed by Photoshop.
The three exposure factors were: Aperture – f/4 | Shutter Speed 1/500 | ISO 1600. We also see the camera was set to manual mode, the metering mode to spot, and there was no flash used.
A bit of background on the photo session – I took these at a dance recital where flash was not allowed. I set the ISO to Auto so that it would adjust as the stage lights varied.
So what went wrong?
My guess is that the spot metering gave too much priority to the white outfit of the ballerina.
Although the ISO went to 1600, when I tried to freeze the action with a shutter speed of 1/500 sec, the aperture opened to f/4, the widest for this lens – a Canon 24-105mm. That still wasn’t enough to properly expose the image.
So let’s look at the EXIF data for a better-exposed shot taken at the same event with similar lighting.
This was a better exposure under the same lighting conditions. Why? The EXIF data tells the tale.
Filename – IMG_3122.CR2
Make – Canon
Model – Canon EOS 6D
ExposureTime – 1/250 seconds
FNumber – 2.80
ExposureProgram – Shutter priority
ISOSpeedRatings – 800
MeteringMode – Multi-segment
Flash – Flash not fired
ExposureMode – Auto
White Balance – Manual
ISO Value – Auto
Metering mode – Evaluative
White Balance – Tungsten
Lens Model – EF70-200mm f/2.8L IS USM
Note the metering mode here was Evaluative. The ISO was lower at 800, but the shutter speed was slower at 1/250 second. The real difference is the f/stop.
Using a faster lens, the Canon 70-200mm with a maximum aperture of f/2.8, combined with the slower shutter speed, and the exposure is closer to correct without editing. The evaluative metering mode also did a better job.
The ability to view EXIF data later is like reviewing your notes for insights into what worked and what didn’t.
The beauty is, your camera keeps those notes. As a forensic pathologist might use the tools, lab tests, and analytical methods when performing an autopsy, you as a photographer investigating your photo, can learn much from EXIF data.
I like Irfanview for its simple means of viewing EXIF information. However, more standard programs like Lightroom and Photoshop can easily view EXIF data as well. Many other programs will show EXIF data, some displaying more information than others.
Focus
If your photo is incorrectly exposed, you may still be able to make it acceptable with editing adjustments, especially if you shot in Raw and didn’t push the highlights or shadows too far.
When an image is out of focus or blurred, however, there are no tools to resurrect it.
So let’s look at how our forensic analysis of an image can help us understand what photo mistakes we made and how to avoid them in the future.
No guessing here… this one is way out of focus. You can fix exposure mistakes, but out-of-focus photo mistakes render your image DOA.
Out-of-focus vs blurred
When what we want sharp in a photo isn’t, there are two possibilities; the image wasn’t focused properly, or the image is blurred. What’s the difference?
Being able to look at your image and detect the problem and then further using EXIF data will tell the tale.
There are two reasons why things may not be sharp in your image:
1. Out-of-Focus – The lens was not focused on the subject you wanted in focus.
There are two subcategories of this:
- Nothing in the image is focused, or
- Some things are focused, just not what you wanted.
The image at left is totally out of focus, while the image at right has focus, but at the bottom of the frame and not on the rider. The image in the center is what we want. Using continuous-servo autofocus was the ticket to getting sharp shots of these fast-moving riders.
Breaking those two down, if nothing in the image is focused, was auto-focus turned off? If you focused manually, did you fail to achieve sharp focus?
If some things are in focus, but not what you wanted, where did you have your focus point? Often newer photographers fail to realize, by default, most cameras use the center focus point. If what you wanted in focus wasn’t in the center of the frame, it may not be in focus.
The rail is in focus, but is that what was wanted? There’s also something on the lens. There’s little chance for fixing this one.
Depth-of-field is also something to take into consideration. If focus falls off too much in front or behind the spot where the camera focused, it’s time to check the EXIF information to determine what your aperture was.
A wide aperture (like f/2.8 or f/4), will produce an image with much less depth-of-field than a small aperture (like f/16 or 22).
What was your intent?
Understand and use your aperture settings to manage depth-of-field. When things go wrong, also understand how to examine the EXIF data to review what your settings were.
This was purposeful focusing on the shoes of the center dancer. I then used a wide aperture to limit depth-of-field. 1/200 sec. f2.8 ISO 800
Seeing just where the camera focused may take other tools. Many cameras can be set to highlight the focus point(s) used when viewing the image on playback in the camera.
After the shoot, while editing, if you are using the editing tools provided by the manufacturer (i.e Canon’s Digital Photo Professional DPP, or Nikon’s Capture NX-2), the software can show you what focus points you used when you made the image.
I use Lightroom and like the Show Focus Points Plugin (which is available for PC or Mac). It does a nice job of showing the focus point(s) used.
One thing to keep in mind, if you use the “focus-and-recompose-method,” (where you use the center focus point to focus, hold the shutter button down halfway, {or use back button focus}, to lock the focus, recompose and shoot), the display is still going to show which focus point you chose. In this case, the center one.
A good practice is to intentionally select your focus point, not simply using the center one all the time.
The free Focus Points Plugin for Lightroom is a handy tool. Note from the legend, this shot used the focus-and-recompose technique as the focused flowers are not directly under the center point hence the red and white square.
2. A blurred image
It’s possible to have good lens focus but still have a blurred subject. Out-of-focus and blur are different things. There are two kinds of image blur:
- Camera movement blur
- Subject motion blur
Camera movement blur
You can often detect this because the entire image will be blurred. None of it will be in sharp focus.
The common denominator in a blurred image is insufficient shutter speed. In the case of camera movement blur, this happens when the camera is handheld, and the shutter speed is insufficient to freeze the shake (often very subtle) of the camera when taking the shot.
Remember, this doesn’t have to be a particularly slow shutter speed, particularly when shooting with long telephoto lenses. The “reciprocal shutter speed rule” says that when shooting handheld, the minimum shutter speed to eliminate camera shake needs to be the inverse of the focal length. So, for example, if you’re shooting a long 400mm telephoto handheld, the minimum shutter speed needs to be 1/400 second or faster.
Image stabilization can help here, so use it when you can. Just don’t expect miracles. A tripod is always the best prevention for camera movement, and when on a tripod, switch off image stabilization.
Subject motion blur
Things that were still in the image may be sharp, but moving subjects may be blurred.
When subjects are moving, and we are taking still photos, we need a shutter speed sufficient to freeze the action if that is our intent. What shutter speed that might be is dependent on the speed of the subject, the direction the subject is moving relative to the viewing angle, and the size of the subject in the frame.
A racecar moving perpendicular to the camera angle, say left to right, at close range, will require a faster shutter speed to freeze it as compared to the same car at the same speed moving directly toward or away from the camera.
The table below may help you understand typical shutter speeds to freeze moving objects.
Aaron Sussman’s The Amateur Photographer’s Handbook (7th ed., 1965, Thomas Y. Crowell, New York) p. 210. *A=toward you, B=diagonal movement, C=right-angle movement, as the arrows show.
The subject is in focus, but the slow shutter speed wasn’t enough to freeze the action. This is motion blur. 1/25 sec. f2.8 ISO 1000
Sometimes we want some creative blur with moving objects. Understanding how to use shutter speed, intentional camera movement (like panning), long exposure techniques, and things like second-curtain sync flash, can add creative looks to our images.
Remember our friend, EXIF data, however, when you make those photo mistakes, and things don’t go as planned. Practice photo forensics to determine what killed your photo.
The was desired motion blur combining a relatively low shutter speed, panning with the action, and second-curtain sync with a flash. 1/60th sec. f/5 ISO 400
Lens hygiene
You look at your images in edit and see a big fuzzy spot on them in the same place on sequential images. Most of the image is in focus, but an area may be blurred or show lens flare. This is when you’ll likely do a facepalm. Arrghh!
You had a big smudge on your lens!
Unfortunately, there is no edit fix for this, no warning in the camera that it’s happening, and EXIF data will not diagnose it later.
Yet if you don’t detect it while shooting and clean your lens, you can ruin a lot of shots. You may even ruin an entire session, making this photo mistake. Prevention is the only answer.
Periodically check your lens, especially in harsh environmental conditions. Be sure there aren’t water drops, smudges, dirt, or other guck on the lens. Carry a lens cloth and keep that lens clean.
Yes, cleanliness is next to godliness when it comes to lens hygiene.
Keep it clean! An unnoticed lens smudge can ruin a lot of shots if you don’t detect it sooner than later.
Photographing waterfalls in the Columbia Gorge of Oregon on a rainy day is a recipe for water drops on the lens. If you don’t catch them, they can ruin your shot.
ISO and noise
We haven’t discussed the third leg of the exposure triangle – ISO.
In the film days, faster films of 400 or 800 ISO (called ASA back then), would be “grainier.” Today we have cameras that can shoot over 100,000 ISO.
The penalty is that higher ISO settings produce what we call “noise.” This is the digital equivalent of grain. So, if you look at your image and see what seems like too much noise, as a forensic photographer, turn to that same tool, EXIF data. See what ISO you used.
With experience, you will learn what is tolerable for your particular camera. If you use auto ISO, you can also set limits so the camera will not exceed the maximum you set.
It might be hard to tell from this online image, but the photo on the right, taken at ISO 1600, was a bit “noisy.” The “after” version on the left is after a pass with Topaz DeNoise AI… which did a nice job and still retained detail.
It’s important to note that there are tools (and they are constantly improving), to reduce noise in a photo without sacrificing too much sharpness. The new Topaz DeNoise AI, which uses artificial intelligence, is quite remarkable.
Note that in low light situations, where it can be a choice between higher ISO and sufficient shutter speed to freeze action/prevent blur, that while noise reduction tools can help remedy a noisy photo, there is no cure for a blurred image. Cranking up the ISO may be the lesser of the evils.
Photo CPR
Using photo forensic tools like the histogram, EXIF data, and editing programs that can adjust badly-exposed images, you may find that the image you pronounced dead can still be resuscitated.
It could be it’s time for some CPR – Critical Photo Recovery.
Viewing the histogram can tell you if you crushed the shadows or blew out the highlights. If there’s no detail left or if you might still recover them.
Using the highlight and shadow clip warning tools in Lightroom, you can check. The highlight clip warning displays completely white pixels in red, and the shadow clip warning shows totally black pixels in blue.
Even with a poorly-exposed image, if when turning on those features, you see little or no red or blue, you have not taken the image outside editable limits.
The image straight out of the camera was underexposed, but the histogram showed it was recoverable. Using some “CPR” – Critical Photo Recovery techniques, it came back quite nicely. You don’t want to have to routinely rescue images with editing, but it’s nice to know how when necessary.
Many photographers preach that “getting it right in camera” is the ultimate goal. I would concur the closer you can come to this ideal, the better.
In the real world, however, the variables of lighting situations and the limitations of camera dynamic range can make getting the “perfect exposure” an elusive goal.
Part of being a good photographer is being a good photo editor. Yes, editing should not routinely be a “rescue mission” where you’re constantly working to compensate for poor camera skills. On the other hand, even the most perfect image out-of-camera will still need some skills to put the polish on the camera’s Raw file.
A good editor can use CPR skills to bring back many photos, and when the image is good right out of the camera, take them from good to really great.
Warning signs – Photo triage
You can learn a lot by reviewing your poor images and performing “photo autopsies” on them after you’re back in an edit session. You will hopefully discover what went wrong and not make those photo mistakes in the future. However, discovering a problem while still out shooting is even better.
Making a bad image happens to even the best photographers. Not discovering the mistake quickly, however, and shooting a whole sequence of poorly exposed, out-of-focus, or blurred shots…that’s a disaster.
Fortunately, modern cameras have built-in warnings and assist features that, if you pay attention, can help you avoid photo mistakes. Here are a few to get familiar with:
- Over-exposure warnings – “Blinkies” or “Zebra Stripes” are indicators of blown highlights. Understand how they work and use them.
- Live Histogram – We spoke of the value of a histogram in determining if your exposure is in-bounds. One advantage of mirrorless cameras is many will allow you to view a live histogram before you make the shot. Being able to do so will tell you if you need to make adjustments for exposure. Some DSLRs will allow for a live histogram on the LCD with the mirror flipped up. On others, you’ll have to settle for a histogram on a previously shot image. Even so, checking it, especially when shooting in difficult lighting situations, is a good idea.
- Focusing aids – Indicators like focus peaking, focus point indicators, and the focus lock beep can help you determine when and where focus has been achieved. Using Live View on a DSLR and digitally enlarging a portion of the image (or doing the same on a mirrorless camera) can help you get critical focus where you want it.
- Spot-Metering Warning – Many cameras will warn you if you leave the camera in spot-metering mode. Spot metering can be useful in special situations, but leaving it on when you don’t need it will cause all kinds of exposure havoc.
- Chimping – Some photographers will disagree, but I’m a big believer in taking advantage of image playback and review on your LCD. You may not want to do this after each and every shot, but especially when shooting in difficult lighting conditions, it can help you make corrections if needed. Check exposure, focus, for lens smudges, or any other “gotchas.” Far better to chimp, discover and be able to remedy a problem in the field, than to get back and find your photo mistakes when editing.
Some might scoff, but I’m a big believer in “chimping” my shots. Far better to discover and fix photo mistakes in the field rather than wait until you find them in an edit session.
Learn from the dead, save the wounded, and fight on!
“There are no mistakes or failures, only lessons.” – Denis Waitley
If you are a new photographer, you might think that one day after much experience, you will no longer make photo mistakes. All your shots will be keepers. They’ll be perfectly exposed, sharply focused, so good they will never need editing. They will be superb right out of the camera.
Here’s a reality check – that won’t happen.
Further, if you never make a bad shot, chances are you’ve stagnated and are not trying new things.
So, the take-away from this article should be that you will use the “photo autopsy” method I’ve described to analyze and learn from the “dead.” The unrecoverable images you will ultimately delete. You will learn to determine which images you can save with editing techniques and the tools to do that.
And finally, you will pay close attention to what you’re doing while photographing, so you have turned previous failures into lessons.
To modify the quote above, remember – “There are no photo mistakes or failures, only lessons.”
Feel free to share some of the big photo mistakes that you’ve learned from in the comments!
The post Photo Mistakes? Learning from a “Photo Autopsy” appeared first on Digital Photography School. It was authored by Rick Ohnsman.
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