On August 21st, a total eclipse will be passing over the entire United States. This hasn’t happened for almost 100 years. The total eclipse will pass over many states: Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky Tennessee, Georgia, North and South Carolina. It will take several hours to pass across the U.S. with it only being visible as a total eclipse for as short as 2 minutes in many locations.
Don’t look directly at the eclipse with the naked eye or through a view finder without appropriate eye protection.
Photographing an eclipse without appropriate filters can cause damage to your camera.
The links below will provide details on How to Photograph and View the Eclipse Safely.
Recently, it become apparent that some students have trouble understanding the relationship between Aperture, Shutter Speed and ISO and how they effect exposure for a given photograph. First let’s define each:
Aperture or f Stop – is the size of the opening in the lens that allows light to hit the camera’s sensor. f stop is expressed as a fraction. An f/3.5 lets in a larger amount of light than f/16. Aperture also effects the Depth of Field (DOF). Depth of Field is area in front of the subject and behind the subject that is in focus. More about DOF in a later blog, except to say that larger f stops give smaller/narrower DOF’s.
Shutter Speed – is the length of time the shutter is open allowing light coming through lens to the camera’s sensor. If you are taking photos handheld, my recommendation is to never use a Shutter Speed less that 1/50 second, often displayed as 50 on your camera’s LCD and/or in the view finder.
ISO – is the sensitivity at which the sensor operates. The higher the ISO number used, the greater the sensitivity, the better the camera’s ability to shoot in low light conditions. However, higher values may give the photo a grainy appearance. I recommend not using Auto ISO. From my observations of students photos, the quality of the photos suffer because Auto ISO often allows for too slow a Shutter Speed and results in a blurred photo when the camera is hand-held.
When shooting in Automatic Mode the camera controls all three, Aperture, Shutter Speed and ISO. Automatic does not necessarily give a good photo. I’m an advocate of taking control of the camera. Once you understand how your camera works, you will take better photos.
Below is a student photo taken in Automatic Mode. This photo is one of the first pictures taken with a new camera. The photo is dark and blurred. Note the Shutter Speed of 1/20 second.
Aperture, Shutter Speed and ISO are all tied together to get a photo with the correct exposure. In Automatic Mode the camera makes all the choices. When you shoot in any mode other than Automatic, such as Aperture or Shutter Speed Mode you have more control over the resulting photo.
In manual mode, you have total control of all three which gives you the greatest amount of control, but also the opportunity for failure. I recommend new students start with Aperture Mode and use Shutter Speed Mode when you want to stop the motion of the subject.
Where do you start?
When you use your camera in Aperture Mode, denoted as an A on your camera’s mode dial, you control the size of the lens opening and the camera sets the Shutter Speed. Remember you want the minimum Shutter Speed to be 1/50 or faster for hand-held photos.
In Shutter Speed Mode, denoted as S or Tv, you are selecting the Shutter Speed and the camera controls the Aperture.
First set your ISO. What setting do you use? Are you outside on a sunny or partially cloudy day? Try ISO 200. If you are inside a building with good lighting ISO 200 or 400 could be a good place to start. In early morning or evening around sunrise or sundown you may have to use something like ISO 800 or higher.
In a concert hall you may have set the ISO much higher depending on the lighting. The concert photo to the left ISO 2500 was used.
In Aperture Mode, remember that the camera determines the speed for the ISO and Aperture you set. Let’s look at the Photos 1 & 2 below. Do you see any differences in the photos?
Hopefully your answer is no. In Aperture mode, the camera compensates for the different values in aperture f/5.6 and f/22 by a corresponding change in the time the shutter is open. You see that for the smaller aperture f/22 the time was 1/125 much longer than the 1/2000 for f/5.6. Let’s see what happens when we change to ISO 800, but still use the same Apertures as before.
All four photos look about the same. Why? Because the camera compensates for changes in Aperture and ISO to always yield a good exposure.
What would happen if you chose to operate the camera in manual mode, which would allow changing Aperture, Shutter Speed and ISO independently? How would Photo 4 change if the Shutter Speed was 1/125? Would it brighter or darker?
Scroll down to see.
The answer is “Brighter”. Did you get the answer correct? The slower speed 1/125 lets in more light than 1/350, so the photo would be over-exposed, i.e. Brighter.
Had an ISO higher than 800 been selected the resulting photo would have been darker than in Photos 1, 2, 3, and 4. At a higher ISO, the sensor would have been more sensitive to light and would require a Shutter Speed faster than 1/8000, or an Aperture smaller than f/22 both of which are beyond the capability of the camera and lens used in the photos above.
I hope this helps you better understand the relationship between Aperture, Shutter Speed and ISO.
The link below from PetaPixel.com should help with your further understanding of Aperture, Shutter Speed and ISO.
Sorry it’s been so long since I last posted to my blog. My wife and I recently took a road trips to New Orleans and Boston. Needlessly to write, I was preoccupied. At the end of this blog I’ve shared a short video with some of the highlights from both trips.
Here’s my long ago promised discussion of metering modes.
Today’s digital cameras have several available metering modes. Below you will find the most popular. Icons shown are typical on most cameras.
Evaluative/Matrix/ESP/Pattern (Overall)– Determines exposure based on the entire image. Some cameras have a bias to the exposure at the point of focus. I’ve found for most situations this mode of metering does quite well.
Center-Weighted – Determines exposure based on the subject and background lighting with a bias to the center of the view finder.
Partial – Determines exposure over a large circular area than with spot metering. This mode is available only on Canon cameras and it appears has replacde the spot metering on the newer models.
Spot – Determines exposure based on the small area in the center of the view finder. Best for strongly back-lighted subjects.
So do all cameras yield the same results? Generally, I think they do when using the Overall metering mode. Here’s a couple of comparisons under the same lighting conditions and settings.
A second pair:
As we look at each pair of photos and observe the Histogram in the upper right, we see each is quite similar. With these combination of cameras, Sony, Canon and Olympus, the results are similar with the small differences likely due to how the photo was framed/composed.
So what happens when you use Center Weighted vs. Overall mode?
As we see in the Center Weighted metering, Photo 1, the color of the flags are brighter and more true in color than Photo 2 where Overall was used. Obliviously, the camera did a better job with Center Weighted metering, under these lighting conditions.
What metering mode is best when taking a photograph with a bright sky and dark foreground? In Photo 3, the metering mode chosen was Overall, in Photo 2 Center-Weighted was used. As can be seen the foreground in Photo 4 is slightly brighter that in Photo 3.
What would happen if Spot metering is used? In Photo 5 you see the sky is too bright, i.e. over exposed. The best exposure for this scene was gotten using Center-Weighted.
What if you were to use the Spot metering, vs. Overall metering? Photo 6 below was taken using Overall metering.
In Photo 7 below Spot metering was used. The metering spot was taken on the bright face of the building. This photo is too dark i.e.under exposed.
Photo 8 below was taken using Spot metering. The metering spot was taken on the dark face of the iron. This photo is also dark i.e.under exposed.
What do we see here? Once again the Overall mode, Photo 6, had the best exposure. In addition, when we compare Photos 7 & 8, we see where the spot reading is taken can make a significant difference in the resulting photo.
What are the lessons learned:
Overall mode works well a good portion of the time.
Where the subject’s exposure is important Center Weighed Metering may provide a better result.
Spot metering should be only used in back lite situations. Where the Spot metering reading is taken has a significant effect on the photo’s exposure.
My advice to better understand metering modes, is to take many different photos under different lighting conditions using all metering modes. Compare the photos and see which are best with your camera. Getting consistently good photos takes practice.
What is white balance? White balance (WB) is the process of adjusting the colors in an image so they are realistic and accurate. Our eyes have no problem with white balance, but cameras can have problems. As my students know I place emphasis on getting the exposure correct in the camera. It’s equally important to get WB correct and make the best choice in your camera.
If the WB is not correct your photos may have a blue, orange or yellow cast . These color changes are caused by the color temperature of the light sources in the photo and the camera’s difficulty in choosing the correct setting.
The chart below illustrates how the Color Temperature varies with different light sources.
Each of the six photos below were taken using different camera white balance presets.
The photos below were taken on a sunny day (no clouds) at about 10 AM. As can be seen the Auto WB (AWB) and Sunny preset yielded the similar results. Makes sense, right? Sunny day!
But what happens when you use the wrong preset? In the next four photos I used the Shade, Cloudy, Tungsten (domestic lighting) and Florescent settings. You will note that with each of these settings the photos have yellow or blue casts when compared to the photos above. Here the camera was set to the wrong WB for the lighting conditions.
OK, with AWB the camera did a good job of determining the correct white balance. So why not use it all the time? I would agree under some conditions it works well, however there are cases when AWB just doesn’t work.
The AWB photo (below left) gave a result that is too yellow.
In the photo you will see a card is propped up against the lamp.
Professionals sometime use something called a ‘gray card’to assist in
getting a reference point for the correct WB. A gray card can be purchased, if you want, at most photography stores or online.
In the photo (below right) I used the gray card and the levels adjustment in Photoshop** to correct WB. I could have used the card to create a custom WB setting in my camera, but didn’t because I wanted to easily compare results. (See your camera manual for how to do custom WB with your specific camera)
I then re-shot the photo using the camera’s Tungsten WB setting as you see in the photo below, the results are similar to the Photoshop** corrected photo, though a little less yellow cast which personally looks more natural to me.
A second example below left, was taken by a friend, using AWB . The colors of the four rings are turquoise, purple, cobalt blue and red. As can be seen, the AWB didn’t do a good job of getting the colors correct. I learned the photo was taken with lighting from a table lamp. Using a white balance correction in Photoshop** I shifted the color temperature towards yellow, Tungsten. This improved the colors, but further color adjustment would be required in Photoshop** to be able to better distinguish purple and cobalt blue rings. If the Tungsten WB had been used in the original photo, colors would have been closer to the actual from the start.
Summary: What does this all mean? I believe the best choice is to use your camera’s WB, presets, i.e. Sunny, Shade, Cloudy, Tungsten and Florescent.
However, when taking photos outside in generally sunny, partly cloudy or a mixture of sunny and shady conditions AWB should work satisfactorily most of the time. Otherwise, I’d use the WB presets, your choice and preference. Explore the different WB’s available on your camera for different lighting situations and see what works best for you.
Using the WB presets is specially important for indoor available light photography i.e. Tungsten and Florescent. In the case of mixed lighting, where you have both natural i.e. sunlight and indoor lighting it becomes a little trickier. I’d recommend taking photos with both AWB and the appropriate WB for the indoor lighting. In the case of mixed lighting, the use of the gray card should be helpful. When using a flash indoors I’d recommend setting the camera for Flash WB. I’ll share my thoughts on flash photography in a future blog.
The links below will give you greater detail on How to Set a Custom WB.
** When I use the term Photoshop, I’m using it generically to mean any photo post processing software that allows for making corrections to your photos.
See my prior blog post Photo Processing Software if you wish additional information on photo processing software.
If you have any Questions please feel free to contact me
In my last blog post, I introduced Auto Exposure Bracketing (AEB) and Exposure Compensation.
Here I would like to explain more about using Exposure Compensation .
The photos below were taken using AEB in Aperture Priority Mode i.e. the camera determines the shutter speed. (Note: I targeted the train station using spot metering)
A total of five photos each one exposure value (EV) apart were taken. It’s important to note the change in the speed for each of the EV changes and how the histogram shifts right or left with the change in EV.
As you decrease the exposure by 1 EV the photo gets darker and the speed increases i.e. doubles 1/250 to 1/500. If you increase the exposure by 1 EV the photo gets brighter and the speed decreases 1/250 to 1/125. For a decrease by 2 EV the speed doubles again from 1/500 to 1/1000 and if you increase by 2 EV the speed changes from 1/125 to 1/60.
Normal (1/250 sec)
-1 Exposure Value (1/500 sec)
– 1 EV
+ 1 Exposure Value (1/125 sec)
+ 2 Exposure Value (1/60 sec)
-2 Exposure Value (1/1000 sec)
Digital cameras allow you to set EV Step to either 1/3, 1/2 or 1. (See your camera’s manual on how to set the EV step for your particular camera.)
In the photos below I adjusted the camera by +1/3 EV each time. As you can see the difference in each photo is very slight. Therefore, I believe an EV step of 1/2 would have been sufficient as there is only a very small change in each of the exposures.
Remember the goal is to get as close to ideal exposure as possible. While you have the ability to make corrections to exposure, along with contrast, highlight and shadow detail using photo processing software, it’s important to get the exposure correct in the original photo. When making changes to exposure on your computer/tablet there is the potential to add noise that will degrade the quality of the image. Had I chosen a different metering mode the image results would/could have been slightly different, but that’s a topic for a future blog post on metering modes.
In a previous blog on Histograms, I included photos where I had used Auto Exposure Bracketing (AEB). So why and when would you use AEB? I see a couple of times when it really makes sense: 1) when you are not sure what is the best exposure set-up under changing light conditions, 2) when you have high contrast lighting such as in night photography.
When AEB is used, the camera will automatically adjust either aperture, speed and/or ISO while keeping the other two constant depending on the camera shooting mode you are using. I believe that setting the ISO and aperture and having the camera bracket the exposures by changing the speed provides the best results under most circumstances. In fact, when using AEB I use aperture priority for most of my photographs. Using aperture mode allows me to have better control of what is in focus and the depth of field of my photos. Actually, aperture priority is my go to mode for 95% of my photos. Your camera’s user manual will go into the specifics as to how to set your specific model for AEB.
1) Several years ago on a trip to Amsterdam, my wife and I took a boat trip through several of the canals. As we traveled along the canals, we were moving from shadows, to cloudy and sunny conditions. I set the camera up to do AEB with three exposures: normal, plus one f-stop and neg one f-stop.
– 1 F stop
+ 1 F stop
– 1 F stop
+ 1 F Stop
Photos above are unprocessed Raw Files
Also the camera was set to use continuous focus (CF) and multi-exposure mode, so when I depressed the shutter button all three photos were taken one after another. Why didn’t I just take a single photo and correct the exposure when I downloaded it to my computer? When you make adjustments to your photo on the computer, there is always the potential of increasing the noise in the original photo. So, it’s important to get the best exposure possible when taking the photograph. I could have accomplished the same correction when I shot the original photo by using the exposure compensationfeature, but when you’re standing on a moving boat it’s impossible to make the exposure compensation correction and still capture the picture. The continuous focus (CF) and multi-exposure mode, is just as I recommended in my blog on Photographing Children , where I wanted to stop the motion of a constantly moving child. Here I wanted to compensate for the moving boat.
2) I’ve used AEB in night photography because it often presents a high contrast situation, i.e. bright lights and dark shadows. In situations like this it’s important to use a wider range of F stops: normal, plus 2 F stops, and neg 2 F stops. This technique is referred to as High Dynamic Range (HDR).
Always use a tripod as the exposures can be long. It’s imperative that you also use a cable release, or remote triggering of the camera. Any contact with the camera will cause the images to be blurred. In the example below the exposure times ranges from 0.6 to 10 seconds.
Normal 2.5 sec Exposure
-2 F stops 0.6 sec Exposure
+ 2 F stops 10 sec Exposure
Using the three photos above, I combined them using Photoshop’s HDR Merge, and then cropped, sharpened and increased the clarity.
Private/Semi-private lessons are available see Classes
A week ago on Saturday morning, I held a photo walk in Fells Point, one of the oldest sections of Baltimore. The early morning light provided a lot opportunities for good photos in different lighting situations. When we completed the walk I asked if there were any questions? The students felt they would like a cheat-sheet on camera controls.
[At the end of this post there is a Link to a one page PDF copy of the
Camera Controls Cheat-Sheet.]
Shooting Modes: Automatic (Auto) – Camera sets speed and aperture to what it determines to be the optimum exposure for the selected ISO. Program (P) – Camera sets speed/aperture, but you can change the combination of aperture and shutter speed while still at the optimum exposure for the selected ISO. Aperture (A) – You set the aperture and the camera determines speed for the selected ISO. Speed (S/Tv) – You set the shutter speed and the camera determines aperture for the selected ISO. Depth of field (DoF) – Remember a larger aperture, lower f stop (f/3.5), gives a shallow DoF. Smaller aperture, higher f stop (f/16), gives a wider DoF. The closer you move to the subject, the DoF gets shallower. As you move further away the DoF gets wider. ISO – Controls the camera’s light sensitivity. The higher the ISO number used, the greater the sensitivity, the better the camera’s ability to shoot in low light conditions. However, higher values may give the photo a grainy appearance. I recommend not using Auto ISO. From my observations of students photos, I see the quality of the photo suffers because Auto ISO often allows for too slow a shutter speed and results in a blurred photo when the camera is hand-held.
Evaluative/Matrix/ESP– Determines exposure based of the entire image.
Center-Weighted – Determines exposure based on the subject and background lighting with a bias to the subject.
Spot – Determines exposure based on the small area in the center. Best for strongly back-lighted subjects.
AF Target Selection – Camera’s today provide sophisticated focusing capabilities with as many as 11 to 153 individual points determining the image focus.
I prefer more control and recommend to my students to use a single point centered in the viewfinder. The image to the right provides a good example of when you don’t have the camera set to a single focal point. The woman behind the children is in sharper focus. In using the single point focus, you align the center point to your subject then depress the shutter button half-way locking in the exposure.
Exposure Compensation – In some situations you could get better results if you manually compensate the exposure automatically set by the camera. In bright sun on snow objects will seem darker than their natural color. Adjusting toward + will make the subject brighter and closer to their real shade.
Flash Compensation – Adjusts the intensity of the flash. This may be required when shooting a close-up or distance objects.
Digital Cameras have an important feature that you couldn’t get in the days when film cameras were the only choice. Now you get instantaneous feed back as to the quality of the exposure when it’s displayed as a JPEG image on your camera’s LCD screen. In addition, cameras give you several choices of information that can be displayed, such as shutter speed, aperture, lens parameters, “blinkies” called highlight warnings (or highlight alerts) and histograms. I recommend you set up your camera to be able to view the histogram along with the JPEG.
[At the end of this post there is a Link to a printable PDF copy of the text of this blog]
In my last blog I shared this photo and its associated histogram below.
As I noted then, the photo was underexposed.
Below you will see a series of photos and the associated histograms, each with a different exposure. I had set my camera to shoot in AE Bracketing mode. Here the camera shoots a series of photos. In this case, three photos are each 1 exposure unit apart (more about how and why you might want to use AE Bracketing in a future blog).
1 Stop underexposed
– 1 F stop
1 stop overexposed
+ 1 F stop
As you can see from the above photos as each gets brighter the corresponding histogram shifts to the right. Ideally, you would like to see the histogram all the way across, but that doesn’t happen all the time. The shape of the histogram is a function of the tones (bright/dark areas) in the photo. I’ll provide a few examples at the end of this blog, so you can better understand this concept.
Now, looking at both the 1 stop overexposed and the normal exposure photo, I decided that the correct exposure should be somewhere in-between. I made the adjustment you see below on my computer using Lightroom/Adobe Camera Raw. I could have accomplished the same correction when I shot the original photo by using the exposure compensationfeature on my camera. More about the use of exposure compensation in a future blog.
Other photos and histograms examples:
Tybee Island, GA
The Tybee Island Lighthouse photo is correctly exposed. Notice how the histogram fills almost the entire width.
Mt. Saint Michel
In this photo, taken at Mount Saint Michel in France, the area on the left side of the histogram corresponds to the dark areas surrounding the opening. As you see, this area is along the vertical axis and indicates there is some loss of shadow detail. Here’s another opportunity to use exposure compensation in the field. If you can’t make the correction in the field there is some good news. It is possible you can recover some of the shadow detail using Lightroom/Adobe Camera Raw or other photo processing software.
OLYMPUS DIGITAL CAMERA
The Patton Memorial in Avranches, France is over-exposed. Here you see the histogram is shifted way to the right. When this occurs you need to make the adjustment using the exposure compensation feature on your camera. Why? Because it is almost impossible to recover highlight detail using photo processing software. You always need to try to expose your photos to the dark side so that the highlights are not over-exposed as in this photo.
I’ve been teaching basic digital photography for a number of years and have students with just about every make and model camera. I have come to the conclusion that the camera menus are getting more complicated. The features are more numerous than it is practical to learn without many months/years of study. In fact, some features remain automatically activated even when you shoot in other than full automatic mode. These observations were recently magnified when I taught a couple who had just purchased a new camera and were heading to Africa for their honeymoon in a little over two weeks. I was able to spend a total 3 hours with them over two evenings.
This photo is one of the first pictures taken with their new camera in full automatic mode. The photo is underexposed. The histogram shows that clearly!**
In addition the photo is blurry. Why? The shutter speed of 1/20 sec that was determined by the automatic mode is too slow for the camera to be hand-held. I always recommend not shooting with the camera hand-held at any speed less than 1/50 or 1/60 sec. This works well for a normal lens (18-55 mm), but for telephoto lenses you should use a speed at least equal to the 1/focal length (i.e. 150 mm focal use 1/150 sec, 500 mm use 1/500 sec).
My advice to all students is turn off the automatic features. The full automatic mode will, for some percentage of the time, will give you unacceptable results as the photo of the bull dog shows.
I emphasize the use of aperture priority mode as it allows you to better control the depth-of-field (DoF). By controlling DoF you can take control of what is in focus and what is not in focus. Controlling DoF allows you to blur the background and make your subject standout, as can be seen in the photo to the left.
In aperture priority the camera automatically sets the shutter speed based of the aperture selected and ISO you have chosen. If the photo is too dark or blurred, you then adjust the ISO higher to get a correctly exposed and sharp photo. To do this you will need to disable Auto ISO (consult your camera manual or search the internet for a video on how to do this).
Today’s DSLR cameras provide sophisticated focusing capabilities with as many as 11 to 153 individual points determining the image focus.
I prefer more control and recommend to my students to use a single point centered in the viewfinder. The image to the right was supplied by one of my students and provides a good illustration of when you don’t have the camera set to a single focal point. The woman behind the children is in sharper focus. Clearly the camera was set to multi-focus point mode. In using the single point focus, you align the center point to your subject then depress the shutter button half-way locking in the exposure. While still holding the shutter button you re-position the camera to the desired composition and then full depress the button to complete taking the picture.
I was very pleased to see how good the couple’s photos turned out. I can see that they made a real effort to follow the basic techniques we had worked on together. Below are some of the photos they shared with me. All were shot using aperture priority. I am impressed how sharp and well exposed their photos are under different lighting conditions, even the one that was shot at 1/20 sec is good. They really did a great job.
Private/Semi-private lessons are available see Classes
** In a future blog, I’ll be explaining how to utilize the histogram to improve your photos.