March 29, 2013 | Leave a Comment |
There are several ways to get more resolution out of your photographs. Remember these three words: upsample, stack and stitch. Which method you choose will depend on how you shoot a scene. Once you know these techniques, you can choose an exposure and processing method that’s best for a given situation.
If you have only one exposure, your options are limited to upsampling or using software to create more pixels. While the information rendered by software is never as rich and sharp as information that’s optically captured, it nonetheless can be both pleasing and convincing. Upsampling is the best method for images containing moving objects, as other methods require multiple exposures and may produce motion artifacts.
How far can you go? I could give you an overly simple answer: up to 300%. But the true answer is, it depends. Knowing what it depends on will help you choose a method, modify a routine and evaluate results to get optimal results for individual images. How far you can upsample an original depends on many factors found in the source, the destination and the statement you’re making.
You can increase the resolution of a file and improve the detail an image renders by making multiple exposures of the same composition and combining them into a single file. To do this, try PhotoAcute—super-resolution is its specialty, and using it’s as easy as 1-2-3.
How far can you go? A little more than you can with upsampling. Just as with upsampling, how far you can go depends on many factors, including source, destination and the statement being made. The overhead is high with this technique (merging six files takes a little time), but the results are good. Using this exposure and processing method isn’t something I would do with every image, but I would strongly consider it for images where resolving fine detail is particularly important and the technique is practical.
Another method for increasing the resolution of your image files is to break a scene into pieces with separate multiple exposures and then stitch them together using panoramic merge functions in today’s software. It’s a matter of simple addition—two files are better than one, three files are better than two, etc. With this method, detail is optically captured, though you also can choose to enhance it further with software. While you can consider dedicated panoramic software like Kolor Autopano Pro or PTgui for challenging images, it’s highly likely that Photoshop is all you’ll need.
How far can you go? The lens is the limit. Theoretically, you can stitch an infinite number of images. The true limits lie in how much your lenses will allow you to zoom into a scene. Yet, the most important factor still remains: What’s practical in a given situation? Other questions arise. What’s better? Fewer exposures made with a higher-quality lens? Or, more exposures made with a lower-quality lens? The answer lies in how much the quality of one lens exceeds another. Compare manufacturers’ MTF charts (they’re readily available online) for useful objective data that will shed light on this.
So, when you want sharper, bigger digital images from your existing cameras, you have options. Remember, upsample, stack and stitch.
January 14, 2013 | Leave a Comment |
No one needs to learn to “think outside the box” more than photographers. The frame, literally a box, is often our greatest ally. Learning to see photographically is, in part, learning to see within the limits of this box and use them creatively. But there are times when this limits our vision unnecessarily. Once we’ve learned to see within the box, we then also need to learn to see outside the box—and start extending the frame with multiple exposures to perfect select compositions. Extending format techniques aren’t just for panoramic image formats. They can be used to give you the extra inch that can make all the difference in the world for your compositions …
How deep would you like your depth of field? The choice is yours. Today, there are virtually no limits. You can extend depth of field beyond the physical limitations of any lens/camera system with multishot exposure practices and software that composites multiple exposures.
To do this, you first need to make a set of focus-bracketed exposures, optimizing focus in different image areas. How many exposures you’ll need will depend on how much depth of field a scene contains. At a minimum, make two exposures: one focused on the foreground and another focused on the background. Making three exposures is better, one each for foreground, middle ground and background. When dealing with extreme depth of field, like macro photography, you’ll want to make more exposures, at least three, probably six, possibly more. When in doubt, make more exposures than you think you’ll need; you don’t have to use them all when you stack the separate exposures, but they’ll be there if you need them. Unlike bracketing for HDR, it’s almost impossible to automate these types of bracketing sequences in-camera as focus needs to be adjusted for each frame. However, for tethered shooting, you can use software such as Helicon Remote to take control of your camera and automate this process and other bracketed sequences like HDR and time-lapse. Whenever possible, use a tripod to make focusing during exposure more precise and registration during postprocessing easier. While using a tripod always delivers more reliable results, don’t let this stop you from trying this technique handheld, especially with simpler sequences, like those used in landscape. You may notice that in cases involving extreme depth of field, the relative size of objects may change between individual exposures. These effects will be adjusted automatically during the merging process.
You can get highly technical with this technique, but I recommend keeping it as simple and practical as possible—so that you’ll use it more frequently. Develop this new habit, and you’ll quickly find many situations where focus stacking will help you make images of superior technical quality …
November 20, 2012 | Leave a Comment |
Use these 8 essential practices to achieve optimally focused exposures.
Set focus in an image intentionally; placing focus in an image unintentionally is usually a deal breaker. Switch autofocus mode to AI Servo only for subjects that are moving predictably. Use manual focus for times when auto focus is likely to fail you, typically scenes with low contrast, including but not limited to low light and night photography.
2 Eliminate Camera Blur
Use a tripod whenever practical. Lacking a tripod, use a nearby prop to stabilize the camera during exposure. When shooting hand, held brace your body in a stable position. Whenever appropriate use the minimum shutter speed you can hand hold without motion blur; for most people this is 1 second divided by the focal length – i.e. 50mm + 1/50th of a second. Shoot in bursts of three or more; nine times out of ten one exposure will be sharper than the others.
3 Use Sharp Lenses
Higher quality lenses not only deliver sharper images, they do so from center to edge and with minimal chromatic aberration (caused by a lenses inability to focus all wavelengths of light on the same plane). Compare lens MTF charts to see how sharp a lens is and when it is sharpest.
4 Use The Sharpest Aperture
The sharpest aperture, generally f8 or f11, varies from lens to lens. Test your lens to find out which aperture is sharpest. The smallest aperture (f22 or equivalent) delivers the greatest depth of field (acceptable lack of focus) but slightly compromises sharpness in image areas that are perfectly focused. It’s a trade off; make it only when it’s beneficial.
5 Use Image Stabilization
Use image stabilization for hand-held exposures, especially for exposures with shutter speeds slower than 1 divided by the focal length of the lens. Don’t use image stabilization while shooting on a tripod; here it will compromise rather than improve sharpeness.
6 Use Lower ISOs
Keep noise low. It can compromise inherent sharpness.
7 Optimize Contrast
Higher contrast images look sharper.
8 Master Digital Sharpening
While they can’t make an out of focus look in focus, digital sharpening routines can make a perfectly focused original look even sharper.
November 9, 2012 | Leave a Comment |
What settings should you use when making exposures in low light or at night? Use a tripod and cable release, set ISO to 800 (or higher), open up f5.6 or wider, focus at infinity and keep exposures below 20 seconds. While this is a good starting point, that’s all it is, as you’ll need to modify settings based on the specific light(s) in a location, the equipment you’re using, and the effect you want to produce. Instead, ask, “What concerns do I need to be mindful of and what points of control do I have when making low light or night photographs?” Develop your sensitivity to these factors and you’ll know why and when to improvise and even what more you can explore. These twelve tips will give you a solid foundation from which to begin your explorations in low light and night photography.
1 Use A Tripod
Tripods are essential for long exposure techniques. The tripod head you use is as or more important. Use good ones.
That said, don’t feel like you have to make all of your low light exposures on a tripod. Today’s digital cameras offer exceptional high ISO performance that open up a whole new range of light for us all.
2 Use A Cable Release Or Intervalometer
Minimize camera motion by using a cable release to make exposures. (In a pinch, you can use the self-timer mode to delay exposure at least 2 seconds after you touch the shutter release.) Once you’ve composed an image, touch the camera / lens / tripod as little as possible.
If you’re stacking multiple exposures to create star trails, consider using an intervalometer to automate timed exposure sequences.
3 Use Bulb Mode
Bulb exposure mode is the only mode you can use to make very long exposures. Most other camera modes won’t exceed 30 seconds.
4 Use Mirror Lock Up
Further reduce motion blur by using the mirror lock up function on your camera.
5 Use A Fast Lens
Use a fast lens. Each fstop offers twice the amount of light as the previous one, which will translate into an exposure that lasts half as long (reducing motion artifacts) or one lower ISO rating (reducing noise).
If you can pick up the speed you need with high ISO (without noise becoming unacceptable) and image sharpness is a primary concern, consider using sharper apertures. The sharpest aperture on most lenses is either f8 or f11. Confirm if this is true with an individual lens by testing it, preferably before making exposures at night.
When you’re shooting on a tripod don’t use image stabilization, it will reduce rather than increase sharpness.
6 Find Infinity Focus Point
Test your lenses and find the most used point of focus - infinity.
When possible, use a flashlight to illuminate objects to focus on, focus, then immediately turn off auto-focus, if you haven’t already.
7 Use High ISO
New digital cameras offer extraordinary high ISO performance. Test your camera to find the upper limit when noise becomes unacceptable. Use this when long exposures are likely to cause unwanted motion artifacts.
8 Check Histograms
Monitor histograms after every exposure. An exposure’s histogram will tell you if the shadow or highlight detail has been lost, if underexposure is likely to produce noise, and if you need to make multiple exposures.
9 Consider HDR Techniques
Histograms will tell you if you need to bracket exposure. Remember, data in the lower half of the histogram tends to be noisy and gets noisier the closer to the black point it gets. To reduce noise, you’ll want to bracket exposures more frequently than you might think, even if you only use the additional exposure(s) for one part of an image (such as the parts without motion) and not another or even one small piece, like the moon. There’s a progression of HDR techniques that will help you with a majority of your exposures, not just your low light photography.
10 Use Long Exposure Noise Reduction
In camera long exposure noise reduction works by taking a second exposure of the same length with the shutter closed to map fixed sensor noise and then remove it from the first exposure. This is particularly useful with longer exposures when sensor noise becomes most pronounced. But doubling exposure times for every exposure may not always be advantageous, especially with shorter exposures at lower ISOs when noise is less pronounced – so learn how and when to turn this camera function on and off.
11 Master Noise Reduction Post-Processing
Learn what kind of noise and how much of it can be removed in post-processing and you can comfortably use even higher ISO settings.
12 Consider Adding An Artificial Light Source
At a minimum bring a small flashlight to help you check camera settings and find equipment in the You don’t have to be in the dark to prepare to make exposures in the dark.
In addition, consider bringing a strong flashlight for light painting techniques. Light up an existing visual element or add a new one with the light itself. Some of today’s compact flashlights are surprisingly strong. Flash units can be another excellent source of artificial light.
You can blend multiple exposures, with and without artificial light sources to control where and how much to introduce light into a composition.
Before you shoot, test, test, and retest. Test what you can ahead of time; familiarize yourself with camera functions, find infinity focus, identify acceptable ISO including post-processing, know at what exposure times you can expect motion artifacts like star trails, etc. The last time and place you want to be testing your equipment is while you’re trying to make finished exposures in exciting locations. Testing ahead of time will greatly reduce but not entirely eliminate on site testing. To optimize your exposures for each unique situation you’ll need to make minor modifications to the general practices you’ve previously established. On site you’ll most likely want to make two types of test shots. First, make a test shot at exceptionally high ISO to confirm composition – and possibly focus. Second make a test shot at acceptable ISO to confirm optimum exposure – if you’re lucky this may be your final exposure, but quite often you’ll find you need to make a slight modification to that exposure or a second or even third bracketed exposure to enhance the first. Optionally, you may want to test what motion artifacts are introduced by extended exposures and if they are pleasing.
There’s a lot left to be discovered in night photography. Use these tips to help guide your explorations.
Many people find it easier to see composition in black and white. If you’re one of them, try setting our camera’s preview to black and white. When you do this, seeing line, shape, form, and relative light and dark relationships may become easier. Doing this will also help you get a better sense of how an image will look in black and white. Remember though, the saturated hues in your image can be converted to black and white as either light or dark, so the relative tonal distribution of your image is quite fluid – and seeing the hues in the image (whether with your naked eye or on the camera’s LCD) will inform you how fluid you can expect it to be, where it will be fluid and where it won’t.
Setting your camera’s preview to black and white will only affect the JPEGs your camera creates; your Raw files will still be in full color.
Here are some commonly asked questions that, once answered, will demystify setting camera file format.
“Should I set my camera to JPEG, Raw, or JPEG and Raw?”
If you want to create files with the highest quality, set your camera to create Raw files. Raw files contain the widest color gamut, highest big depth, have flexible white point, can have highlight and shadow detail recovered, can be reprocessed infinitely, and are free of compression artifacts. Raw files are larger and require post-processing before presentation. They take up more room and they take longer to use.
If you want files to create files to share immediately without (or with minimal) post-processing, set you camera to create JPEG files. JPEGs are excellent for transmission, posting to the web, and print on demand. (Remember, the highest quality JPEGs are the ones created by post-processing Raw files, not the ones created by your camera.)
If you want both Raw and JPEG, set your camera to create both.
A camera creates a Raw file every time it makes an exposure. Setting a camera to create a JPEG file requires it to make a conversion to JPEG, which it does with incredible speed. If a camera is set to JPEG, it will replace the Raw file. If a camera is set to Raw, only a Raw file will be created. If a camera is set to Raw + JPEG it will create a JPEG copy in addition to the Raw file.
“How do you set file format on a digital camera?”
Camera interfaces and terminology vary. On the Canon 1Ds Mark II, you can set image- recording quality by pressing the Quality button (a square icon that breaks into pixels) and dialing to the setting of your choice. Four quality settings are available – one Raw and three JPEG: Large/Fine, Large/Normal, and Small/Fine.
“Should I save my JPEGs in another file format?”
If you edit them, once you edit them, save copies of JPEGs as TIFFs to avoid additional JPEG compression artifacts. Every time you save a JPEG file it’s re-compressed, which causes progressive artifacting and cumulative damage.
Here are five commonly asked questions that, once answered, will demystify camera color spaces.
“Why do my digital camera files have an sRGB profile?”
sRGB is the default color space for most digital cameras today. Most camera interfaces will allow you to change this default. Interfaces and options will vary. The widest gamut default color space most digital cameras support is Adobe RGB (1998). The profile for the camera’s default color space is attached to JPEG files but not to Raw files.
“Is Adobe RGB (1998) the widest gamut I can get with my camera?”
No. The camera sensor is capable of quite a lot more. To access color spaces with a wider gamut than Adobe RGB (1998) you typically need to shoot in a Raw file format. This also allows you to acquire a high bit file – 16-bit instead of 8-bit.
“Where do Raw files get their profiles?”
Raw files don’t have profiles until they are converted into a standard editing space, either with the manufacturer’s software or another Raw file converter like Adobe Camera Raw or Lightroom. Most Raw converters offer a choice of editing spaces including sRGB, ColorMatch, Adobe RGB (1998), or ProPhoto RGB.
“Which color space do you recommend using?”
Use ProPhoto RGB for digital output. It’s the only editing space that can encompass the full gamut of both your camera and your inkjet printer. Use ProPhoto RGB for master files. Make all output specific derivatives from them.
Use sRGB for the web. If a browser isn’t color management compliant, colors won’t be distorted as much as wider gamut color spaces. Use sRGB for derivative files.
“How do I set color space on a digital camera?”
Camera interfaces and terminology vary widely. On the Canon 1Ds Mark II, you can toggle between sRGB and Adobe RGB (1998) by pressing the Menu button and going to the Recording menu (the first icon, a camera), then dialing down to Color matrix and continuing within that to Set up.
During my White Sands, New Mexico workshop, we’ll be photographing in the same area for the next four days. On our first sunrise shoot, I timed the light and how it affected subjects.
5:45 Color on horizon
6:00 Color in sky
6:15 Color bright on horizon
6:30 Highlights on dunes
6:45 Strong texture Large areas of shadow
7:00 Less Less
7:30 Less Less
8:00 Less Less
8:30 Dark sides of dune affected by substantial fill light
12:00 No shadow
3:30 Long shadows
4:00 Substantial shadow
4:30 Fifty percent shadow
4:40 Highlights are accents only
4:50 Sun below horizon, definition falls, pink mountains to east
5:00 Color in sky blooms
5:30 Color in sky largely gone
5:45 Dim light in sky
Now I know what the light will do and when. I’ll use this information everyday for the next three days. So will everyone else. Making notes on site can really pay off. And this is just one kind of note you can make.
Noise comes in three types or patterns:
1) Random noise 2) Fixed-pattern noise 3) Banding noise
Noise often has two components—brightness and color:
4) Image noise 5) Luminance noise 6) Chrominance noise
Knowing the type and kind of noise produced will help guide you to solutions to reduce it. There are three types of noise: random noise, fixed-pattern noise and banding noise.
Random noise appears as both luminance (light and dark) and chrominance (hue/saturation) variations not native to an image, but produced by the electrical operation of a capture device. The electrical signal produced in response to photons is commingled with electrical variations in the operation of the capture device. Random noise patterns always change, even if exposure conditions are identical. Random noise is most sensitive to ISO setting. Again, digital cameras have one native ISO setting; higher ISO settings artificially boost the signal produced by the sensor and the noise accompanying it. The results? You get a brighter picture from less light and exaggerated noise. Since the pattern is random, it’s challenging to separate the noise from the image, especially texture, and even the best software used to reduce it through blurring may compromise image sharpness; how much depends on the level of reduction.
Fixed-pattern noise (“hot pixels”) is a consistent pattern specific to an individual sensor. Fixed-pattern noise becomes more pronounced with longer exposures. Higher temperatures also intensify it. Since the pattern is consistent, it easily can be mapped and reduced or eliminated.
Banding noise is introduced when the camera reads the data produced by the sensor; it’s camera-dependent. Banding noise is most visible at high ISOs, in shadows and when an image has been dramatically brightened. This type of noise is obvious and objectionable; the regular row and column patterns from the sensor quickly call attention to the presence of banding noise, and it’s challenging to reduce without severely compromising image sharpness …
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