Image Sharpness – Part III
We covered getting the image into the camera so now we’ll talk a little about what you do once you’ve acquired it.
Signal-to-Noise Ratio (SNR) is a techy sounding term for referring to what you want in your image as compared to what you don’t want. SNR is a ratio of the lightness values to the intrinsic noise values that your camera generates. You sometimes see noise as multicolored specs that show up when you lighten dark areas of an image. A camera with a higher SNR will tolerate more brightening than one with a lower SNR. And as handy as cropped sensor cameras are for giving you some free magnification, nothing in life is really free. Because the pixels in a cropped sensor camera are physically smaller than those of a full frame camera, they don’t collect as much light, so by definition, their SNR is always going to be less.
But all is not lost when using a cropped sensor camera, even if you underexpose. Hopefully by now you are shooting not in the default JPEG format, but in RAW, so that you can take advantage of the full dynamic range of the sensor of your camera. Although the learning curve for working with RAW images can be a daunting task for sure, the advantages are more than worth the effort. And if you’re not shooting RAW, you can still use much of the same software on your JPEG images. There is a lot of wonderful software available today that helps you take advantage of your camera and its features and especially can reduce the noise while adding some sharpening at the same time. Without getting into a technical discussion of JPEG images, just understand that the file format itself does add artifacts to your image that you have no control over.
Processing your images is where the magic of digital photography is leaps and bounds above that of traditional film and paper photography. Inexpensive and sometimes free software allows us to do things that were either too time consuming or near impossible in the darkrooms of yesterday.
Image blur and poor focus are hard to correct for in the processing. Both create a broadened or almost double edge. Contrast and sharpness however can be greatly enhanced, and should be since they are reduced intrinsically by the camera’s optics and electronics. And although the noise that is generated cannot be completely eliminated, it can be greatly reduced. Just realize that noise reduction tends to soften an image so sharpening will almost certainly need to be applied as well.
Especially with a lower SNR camera, you want to reduce your underexposing of your image. In the film days we were told to “shoot to the right” meaning we were to overexpose a little to make sure we didn’t generate excess film grain in the dark areas. That’s not so true today with the higher SNR cameras. I actually shoot to the left, making sure I don’t overexpose my highlights, knowing that the little noise that does show up can be mostly taken care of with my noise reduction software.
And finally, related to sharpness, contrast can be easily increased in a image as can general exposure and white balance, i.e., making sure your whites are white. This can be useful when you have a shaded subject that is illuminated solely by a blue sky. Since the illumination source is primarily blue, your subject will have a blueish cast to it which should be corrected in your processing.
While the software available to us today allows us to take full advantage of the capabilities of our digital cameras, we really need to make sure that we are starting with the best image possible. Maximizing sharpness and contrast while reducing image and camera blur can be done with some practice and the correct supporting equipment. You don’t have to buy the most expensive of everything but you do want to make sure that you are allowing your equipment to perform as best as it reasonably can by understanding its shortcomings and how to overcome them.
Interested in getting better pictures? Consider one of my private or semi-private clinics.
Image Sharpness – Part II
In Part I we covered blur induced by the subject as well as by the camera system. Now we’ll talk about other contributors to image sharpness.
Poor contrast can be the result of severe convection in the air, particulates in the air such as water droplets (fog), smoke, or dust, flare from light entering the lens at extreme angles, very dark scene (low key), very bright scene (high key), or from poor lens optics.
Although long lenses are very nice for shooting over long distances, they cannot overcome the poor optical quality of the air in between the camera and the subject. Even the best lens will only be able to capture what it has to “see” through. Beware of cool air over land that is heating up. As the heat rises (low density) it will try to mix with the cooler air (higher density) above and density has a huge effect on light (it bends it), and will tend to blur the edges in your scene, thereby reducing the contrast. Just moving to a different location where you are not shooting over the warm ground may be all that is necessary. In many cases though, you have no choice but to accept the poor quality or come back another time.
Inadequate depth of focus can greatly reduce image quality, especially if you are near your illumination limit and are restricted to using your lens wide open. If you can afford to stop down at least a little, you can get more of your subject in proper focus and help to correct for other focus inadequacies. Don’t be afraid to let your ISO creep up a little, especially if you are using good noise reduction software in your processing. I have some fine images taken with a cropped sensor camera at an ISO of 12800! Moving away from your subject, while keeping the focal length the same, can also increase your depth of focus as can switching to a cropped sensor camera.
Improper focus can be tough to tackle. Although auto focus has made amazing advances in recent years, it does not know what part of the image you want in focus. You may have to make minor manual adjustments, something I almost always do anyway. Poor vision or the use of glasses, multi-focal especially, may hinder your ability to achieve proper focus. I prefer to wear my contact lenses rather than my progressive glasses when I shoot, for this reason. Also, you may have a technical issue with your camera or lens that prevents them from achieving focus within specifications. All of these issues can work together to further degrade an image.
Poor or dirty optics can further reduce image quality. You’ve probably heard that it’s best to put your money into your lenses rather than your camera bodies and this is still quite true. The best camera out there can’t do much but capture the image that is coming through poor optics. Teleconverters are a common source of poor image quality. You want to get the very best teleconverter you can afford to put behind your expensive glass. The same holds true for filters. Personally, I don’t use any filters for wildlife photography. While some people swear by a UV or clear filter for protection, I use my lens hood for that. It also does a great job of reducing lens flare from unwanted sources of light.
Make sure you keep your lenses as clean as possible. Fingerprints, smudges, rain, condensation, splashes, etc. can all add up to reducing your contrast and sharpness and therefore reducing image quality. It is useful to carry basic lens cleaning supplies with you. And speaking of condensation, when shooting in warm, humid areas, be mindful of trying to use a cold camera when you step out of an air conditioned car. You could easily spend the next ten minutes waiting for your lens and camera to warm up enough to drive off the moisture. It takes extra long when using large aperture lenses.
Next we’ll talk about the camera sensor itself and some software resources.
Interested in getting better pictures? Consider one of my private or semi-private clinics.
Image Sharpness – Part I
All photographers want their images to be as sharp as possible. There are several factors that can contribute to unsharp images. Blur from subject movement, blur from camera movement, lack of contrast, inadequate depth of focus, inaccurate focus, poor or dirty optics, and low signal-to-noise ratio all contribute to degradation of an image. I’ll take each of these issues and describe what they are, how you can avoid them, and what you can do about them during processing.
First a little primer. Image sharpness is a factor of a number of things but visually, we see things as being sharp when we can easily discern edges. Proper focus definitely helps but even a perfectly focused image can appear out of focus or blurry if the contrast is low enough that edges are hard to detect. Try reading in dim light for a real-world example. One of the first steps in some image detection and recognition systems is to detect the edges. Much of the work I did in my professional career was that of improving image brightness, contrast, and sharpness, all of which play together to create an optimal image.
Blur from the motion of your subject is sometimes hard to control, especially if your shutter speed is already limited by the amount of light, aperture, and usable ISO values you have at your disposal. Always try to keep your shutter speed as high as possible in order to minimize motion in your subject.
Obviously, having the fastest lens and the camera body with the best high-ISO performance is a help but it can also be expensive. Although some inexpensive zoom lenses are very handy, investing in something like the very popular Canon 100-400mm f4.5-5.6 or the Canon 400mm/f5.6 prime lens may be worthwhile. In addition to being a little faster, the optics are guaranteed to be better too.
Blur from camera movement can come from several sources. Hand holding, using an inadequate tripod, having the camera or tripod resting on a moving object, motion from the camera’s mirror, or motion caused by shakey hands or improper shutter release.
Hand holding is fine as long as you follow the rule of thumb that says you want the shutter speed to be as fast as the reciprocal of the focal length. So if you’re using a 400mm lens, you want your shutter speed to be at least as fast as 1/400s. You can certainly get away with shower shutter speeds but when you are getting close to or below this threshold, consider holding your breath, resting against a tree or a solid object, resting your elbows against your chest, and locking the camera against your body as tightly as possible.
I used to avoid using tripods and I’m still not fond of them but after seeing the results I can get by using them, I am rarely seen without one. In fact I finally broke down and paid big money for one that will probably outlive me. But the quality and stiffness of this system is now so much better than anything I ever had before. And with the big supertelephoto lenses I use today, I was way overdue for such a steady support. Most affordable tripods will be made out of aluminum but the better ones are made out of carbon. They are a little lighter than their aluminum counterparts but they are so much stiffer which is important when using heavier cameras and lenses. Also the higher quality ball heads and gimbals are usually well worth the money spent. The used market often offers some good deals.
Using a high dollar tripod doesn’t guarantee great results. You also need to consider the surface you are on and whether or not there is wind hampering your stability. Be careful when shooting on piers or walkways, especially if joggers are frequent. You can sometimes feel every footstep of people who are several hundred feet away and if you can feel it, your camera can too.
And just when you think you have the most stable platform available, your hands can introduce vibrations as well. Consider a wireless shutter remote or at least using the timer which is built into most cameras. Wireless remotes can be had for very little money and are wonderful for reducing shake with long lenses and they can work while in your pocket, making cold weather days more tolerable.
In the next part we’ll talk about some of the optical degradations to image sharpness.
Interested in getting better pictures? Consider one of my private or semi-private clinics.
What’s the Best Tripod?
I often get asked, or read in forums, about what the best tripod is. Like many things in life, what’s best for one person is not necessarily best for another. Only you can define “best”. And, best may change over time as your needs change.
My philosophy about photo gear is pretty much all the same. What’s best is what you are willing to drag out with you. The most expensive tripod is worthless if you never care to take it anywhere. You can read my article about what the best camera is here.
Like most others, I started out hating tripods. After 35 years, I still dislike using them but I have realized what they can do for me so now I use one when I need one, which is much of the time. Here I will present some options for you to consider. It would be worth taking the time to read my three-part article on image sharpness before continuing with this one.
When I started shooting with lenses longer than 200mm and more than five pounds, I felt satisfied with the images I was getting by using a monopod. The monopod is quite useful because it greatly reduces the larger, low frequency movements of the camera-lens assembly – those movements induced by your arms, your breathing, and by the wind to some degree. The monopod also serves as a walking stick while hiking and could be a good item of self defense against wildlife or even other people should the need arise.
Me, using a monopod with a 600mm lens in my early days. Please ignore the goofy hat.
The nice thing about a monopod is that you can get a really good one for not a lot of money. Even the highest priced monopods are not going to be able to compete with an inexpensive tripod so I would never consider putting much money in one. Carbon ones are probably overkill since they are not saving much weight.
For the ultimate in stability, the full tripod is a necessity. Ask any serious amateur astronomer where a good chunk of their investment is and they will tell you it is in their telescope platform. Stability is a must for them and for those photographers who use long lenses, shoot in low light, or do both at the same time, it is imperative that you have a solid support.
I see many make the same transition that I did – starting out with a lightweight tripod. No one wants to carry a heavy one and the professional ones that are lightweight are quite expensive. So many are drawn to the “travel” tripods because they reduce to a pretty small size. Please resist the temptation to get one of these. They are lightweight and compact because their legs are thin and they use multiple sections to get them to a usable height. Even at their tallest length, they are usually a little short for shooting at higher elevations because they force you to bend over to compose your shots and they offer little stability over hand holding.
Using my 500mm f4 lens on an aluminum tripod with a gimbal mount. Photo by Jim Hansen.
Next is the regular line of aluminum tripods that don’t have the “travel” designation. Any of these is probably a good place to start. Even some of the best brands offer models that won’t break the bank. A good one can be had for under $300. I suggest buying a set of legs and selecting a head separately. It doesn’t even have to be of the same brand. Most tripods in this range accept almost any head.
The next step up is the carbon variety and this is where the prices start to jump. Carbon products take more time to build but they result in more stability than what aluminum can provide and they do it with less weight. The downside is their price. Although some can be had for reasonable prices, the professional level ones can easily set you back $900 and that’s for just the tripod legs.
Me, with my long lens and high quality, carbon tripod
I resisted moving to a carbon tripod for a long time. Once I got my 500mm prime lens and realized the quality I could get with it, and especially with the 2x extender connected, I really gained a lot of appreciation for higher ISO values of today’s bodies, image stabilization, and the software available to take a decent image and make it wonderful. But I wanted to shoot at lower ISO values…in lower light…and at objects that were moving. And with the heavier gear, the aluminum tripod that I had gotten used to lugging around with me was no longer stable enough for me.
The first time I literally touched one of the high end, carbon tripods, I was immediately sold on the concept. These tripods feel rock solid and not flexible like their aluminum counterparts. And with one of the quick disconnect bases, you can easily separate the heads from the legs and have a much lighter and more transportable system.
A white ibis hunts for a snack alongside a willet at Little Estero Lagoon, Florida, taken at ground level at 1000mm.
Like with many of the other photographic components, it is usually safe to pick a reputable retailer and start with your budget to find appropriate brands and models. What works for me may not be what you would prefer. I will say that once I made the tough decision to spend the big money on what I thought was just an accessory, it made me realize that the high quality tripod is an essential part of my collection of gear. And because these are at the top of the upgrade scale, they are hard to find on the used market.
Scouting for pictures the banks of the James River in Richmond. Photo by Wendy Darugar.
Whereas I used to avoid using my tripod, even when I had it with me, now it pretty much stays in my truck, whether I am shooting or not. I just don’t leave home without it anymore.
Today, my most prized items are my 500mm prime lens and my carbon tripod. Together they do more to optimize my image quality than anything else I own.
Interested in getting better pictures? Consider one of my private or semi-private clinics.
Anatomy of a Promotional Shot
When doing work for a client, it is important to understand what the images may be used for in the end. Although you are being hired to take a quality image, it is often for a very specific purpose, something that needs to be completely understood and taken into consideration before you start snapping. Remember that although you are being hired because of your abilities, your task is not to make your photography shine but to make your client or their product shine.
In this case, with the band, Runnin’ Shine, the image was to be use for promotion, primarily on social media. The two major platforms for advertising in the local scene are Facebook and Instagram. While Facebook can handle images of almost any aspect ratio, Instagram images are primarily square. The photographer needs to take these final use requirements into consideration. Photographers are taught to compose in-camera and take as tight a shot as possible. For many end uses, a tight shot will look great but be unusable.
I captured all of my shots with plenty of empty space around them to allow for cropping of various aspect ratios and placement of graphics. While I took this one horizontally, I shot all of the scenes vertically as well. Facebook in particular uses several different sizes. For example, an image for an event notice is best at 1920 by 1080 pixels, profile pictures are square, at 180 by 180, while cover photos are nearly 2:1 at 828 by 465.
Original image as captured, with plenty of extra space around the subjects. Not a great final shot but perfect considering what the image will be used for,
I considered the effect of depth of field in this scene to single out the band’s centerpiece performer while still providing adequate focus of the others. Depth of field is a product of not only aperture but also focal length and distance between the viewer and the subject. Although I could have made sure everyone was in focus, the intent of this shot was to single out one while still allowing the others to be an important part of the shot.
In this case, I chose wide open at f2.8 to provided the shallow focus. Because I was relatively close, a short focal length (57mm) allowed the background to come in just the right amount. Had I used a longer lens and shot from farther away, it would have put the background too far out of the focal plane. Camera bodies that have depth of field preview can be useful for seeing the result at stopped down apertures.
Note that I used excessive negative space. I did this to allow for expected, subsequent placement of text/artwork. In some of the images from this shoot, I placed the empty area to the left while I placed others to the right, depending primarily on specific scene composition.
Resulting image appropriate for a Facebook event photo., cropped and resized to the optimum pixel dimensions for Facebook and logo added. Click on image for larger version.
In arranging people in a group shot, it usually looks better to have them sit or stand closer together than they would be if they were in a natural, social setting. Most people like to have some breathing space around them but for photos, it usually looks better to close the gaps between people as much as possible, without making them look crowded. Note that I closed the gaps on either side of the central figure as well.
When using props like the old truck in this case, it is not always necessary to include its entirety, especially if it is large. Note also that I did not include the entirety of the barn. For this shot, the subject is the band while the props were merely accessories. It can be confusing to see more than one subject in an image. Allowing too much of the barn or the truck would have detracted from the band members.
A final consideration is point of view. While I could have taken this shot from normal standing height, I chose to crouch down a little and take it from mid-height. A higher point of view would have looked too common and more like a casual snapshot. Other options include shooting from below, looking up. Shooting from any sort of angle, especially with a wider angle lens can sometimes distort scenes and the subjects in them to the point of being distracting. My job was to highlight the band – not my photography, the latter of which should speak for itself in the final product.
A great image should be a win for your client as well as for you, the photographer.
Check out Runnin’ Shine on the web, like them on Facebook, or follow them on Instagram.
Interested in getting better pictures? Consider one of my private or semi-private clinics.