Sunday, August 25, 2013

Bounce Flash


So what is Bounce Flash? Specifically, bounce flash is any flash that is bounced off of a surface to illuminate the subject, so a mono-block firing into a reflective umbrella is a type of bounce flash. In more common usage bounce flash is the use of an on camera speedlite* which is being bounced off of a wall or ceiling to light the subject. 

A lot of the blog posts I have written on technic have been aimed towards the serious enthusiast or pro who has invested in a wider array of gear and has the option of shooting multiple light set ups or using other modifiers. Bounce flash is a technic which is available to any photographer using a camera that has a hot shoe supporting the use of a speedlite, who has also purchased a speedlite with a swivel head. The minimal need for equipment and the number of mid range cameras, like the SX-50, that offer a hot shoe as an option make this an ideal technic for anybody who wants to do photography on a budget, or who does a lot of photography on the go and wants to be able to travel light.

Apart from the relative in-expense of bounce flash it is also a relatively easy technic to get the hang of on most modern cameras. The majority of newer cameras offer some type of TTL metering. TTL stands for Through The Lens and the camera actually triggers a very brief pre-flash which lights the scene that the camera then uses to judge over all flash power for exposure of the image. This is the equivalent of setting the flash on automatic. This can be used in conjunction with the cameras automatic settings meaning that this technic is available even to very inexperienced photographers.

In general I recommend setting the camera to manual so that you have creative control over ISO, shutter, and aperture while leaving the flash to calculate the needed flash power. As a general rule bounce flash will be used in “Run and Gun” situations where the distance between the flash and the subject is changing and the flash output will have to be adjusted to match. This is what the TTL is designed to do, while it is possible to use this technic without TTL it then becomes more of a walk and gun situation and requires a lot more skill on the part of the photographer to be able to constantly adjust flash output to match the changing scene.

Bounce Flash is one of those technics where there is no specific “right” way to do it, however there is quite a lot of flexibility available to sculpt the light even when using TTL. What follows is a series of four images where the only change is the direction the bounce flash is being fired. All of these images where taken with the Canon 6D set to ISO 200, f8 and 1/180th with the 24-105 f4 L set to 85mm and the camera located 4 feet from the subject. The flash used was the Canon Speedlite 600 EX-RT set to ETTL. The E in ETTL stand for evaluative and refers to a Canon specific algorithm used to determine exposure. Nikon has a similar brand specific algorithm which is designated with an I in their ITTL flash units.

Flash bounced off Ceiling
Flash bounced off Ceiling 



Flash bounced off Wall Behind Camera
Flash bounced off Wall Behind Camera




















Flash bounced off Wall Camera Left
Flash bounced off Wall Camera Left




















Flash bounced off Wall Camera Right
Flash bounced off Wall Camera Right





















Looking at these four images you can see that there is a lot of flexibility in how the light falls on the subject. The primary thing to keep in mind when using this technic is where the light is coming from. In many situations your environment may dictate that by only providing one or two suitable surfaces to reflect the flash off of. It is important to remember that the flash will pick up the color of what ever surface it is reflected off of. In many cases this kind of color cast can be corrected in post as the flash will be lighting the subject and background both and the color cast will be applied to the entire scene. But when possible us a neutral surface like a white wall or ceiling.

If we look at this series a little more in depth, comparing the images where the light was bounced off of the ceiling with the image where the light was bounced off of the wall behind the camera we can see that both images are lit similarly but the light from behind the camera has a much softer quality. Similarly if we compare the images where the light was bounced from camera right and camera left we can again see that the light from camera left is softer. In both cases this is because the surface the light is reflecting off of is farther away allowing the light from the flash to spread out more. 

If you remember in this blog post we briefly looked at bounce flash in the discussion of on verses off camera light quality. In the second and third images on that post the hardness and softness of the bounced light was modified not by changing the distance of the light to the reflective surface but by changing the flash from wide angle (soft light) to telephoto (harder light). The wide angle - telephoto settings in the flash were originally designed so that when used in conjunction with different focal length lenses the flash would only light what was actually in the frame. This allowed the flashes to light subjects that were far away as the output was directed more to the front and not spread out. However for Bounce Flash it gives us more options for sculpting the light. another handy tool, particularly if you have an assistant is a piece of white foam core or other reflector. This allows you to position a reflective surface wherever you want. This is a very inexpensive way to overcome environmental obstacles.

So now you have an idea of what bounce flash is, but the way to really get an understanding of this technic is to just go out and shoot a lot, change the angles the flash is being bounced the distance to the subject, how much in front or behind the reflective surface is and you will quickly begin to understand all the potential this technic has for sculpting light. This method really opens up a lot of creative shooting options for events and parties. 


On Camera Flash for comparison
On Camera Flash for comparison

* In this post I am using the term speedlite as short hand for any on camera flash that is mounted in either a hot shoe or cold shoe and triggered by the cameras shutter.




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Sunday, August 18, 2013

What is Color Balance?


One of the more common mistakes beginning photographers make is not getting good color balance. In most situations, particularly with cameras introduced in the last 3 years the auto white balance function of the camera does a fairly good job most of the time, where it tends to fall flat are areas with mixed light temperatures, so after a brief intro to what color temperature is I am going to focus on ways to correct mixed light situations.

So what is Color Balance? To understand color balance (also commonly incorrectly called white balance) you need to first understand that all light has color. The Color of the light is referred to as color temperature and is measured in degrees kelvin. The warmer the light, that is the more yellow, orange or red the light is the lower the color temperature, as the light gets closer to white and then blue the temperature in degrees kelvin goes up. This seems backwards at first glance, but remember when iron is smelted it starts with a low red glow as it gets hot enough to forge it moves to letting off orange light and when it is hot enough to pour iron starts pushing into the yellow colors. Another way to remember that the high temperatures are the whites and blues is to think of arc welders or lighting. Electric arcs are one of the hottest things we can observe, with temperatures exceeding those of the surface of the sun, and they are in the white and blue color space. For a more complete run down of color temperature click here.

Now you have an idea of what color temperature is, how does it work with color balance? Color Balance is matching the light sources so they all of the same or very similar color temperatures so the camera can then shift the sensor to read white objects as white. It is a subtle but important difference between color balance, matching the light sources, and white balance, setting the camera to read the light sources correctly, but it is an important distinction. It is also why the auto white balance setting will always fail in mixed light. The other common mistake is having a camera set to daylight (essentially white light) and to take photos under artificial light, this is what gives photos that ugly yellow, yellow orange, or yellow/green cast. 

Modern artificial lights tend to be pretty close to 3000k without any green tint. As this gets more common, lower end cameras are tending to have one artificial light setting. High end cameras ,on the other hand, may have four or five artificial light settings (not counting flash, which is generally balanced for daylight). These multiple settings can more closely match the most common color temperatures of incandescent (orange/yellow to yellow) and florescent (yellow to yellow with a green tint) lights. Having these multiple presets can be a quick way to find a suitable white balance if you can not preform a custom white balance. I am not going to go into setting a custom white balance beyond mentioning it is a good idea to use a grey card, because different manufactures have different methods for achieving a custom white balance reading. Consualt the camera’s manual.

For this post I am going through a quick exercise of matching a 5600k Speedlite with modern florescent recessed canister lights. Here is a quick look at the equipment used. For the flash I used a Canon 580EX-II and to match the color of the ambient light I used LumiQuest gel holder. In the photo the gels on the left are used for color correction, The two at the top are a one stop and a two stop neutral density gels which can be used to cut flash intensity on flash units with a fixed power output. The gels on the right are used for Creative Lighting with Color (an upcoming post). For this entry I am only going to speak about the gels on the left. Starting at the top and moving counter clockwise we have a 1/2 stop (or cut) Color Temperature Green (CTG) followed by a 1/4 cut CTG, 1 cut Color Temperature Yellow (CTY), 1 cut Color Temperature Orange, 1/2 cut CTO, 1/4 cut CTO and finally a 1/2 cut Color Temperature Magenta. 

Speedlite with Gel Kit
Speedlite with Gel Kit

As a general rule the CTY and one of the CTGs will be used together to balance older florescent lights, newer florescent bulbs do not tend to have the green tint. The CTO,s will be used for incandescent, but actually look to see what color/s  are most prevalent. The CTM is used on your subject, usually used as fill, when the subject is placed in a green screen environment. In a green screen environment background light reflects off of the screen and will give the subject a green cast. By using a CTM on the subject the green tint is neutralized. If you use photo editing software in the white balance section you have probably noticed a slider that goes from yellow on the left to blue on the right and a second slider that goes from magenta on the left to green on the right. These colors are directly opposite each other on the color wheel and mixing them together neutralizes there impact. In effect your camera does this as its white balance function.

Ok, now you have the theory, lets look at it in practice. All four of these images are just a succession of photos of a white wall. The first image below is the color of the light in the room from the canisters lights when the camera is balanced for the color of the flash. The second images shows the flash firing and the ambient light being crushed out by the camera’s high shutter speed. When this is an option this is the best fix for the light. But it is not an option if you want a slower shutter speed to allow motion blur, or if you are shooting in an environment where blasting everything to white would not look natural, like a club for instance where doing so would destroy the ambience. I have included the histograms so you can better understand the differences in the light color that is causing the shift in the light. 

Image 1 and Image 2
Image 1 and Image 2

Looking at the first image you can see the light in this room has a definite orange cast to it, and looking at its histogram you can see how spread out the different colors of light are. Looking at the second image you can see how the light casts a gradient across the wall, even though the histogram covers a large part of the graph it is fairly uniformly grey as all of the colors are mixed fairly evenly giving us white light. 

The third and fourth images show blending and then correcting the light. In the third image the flash has not been adjusted but the shutter has been drastically reduced so that both the flash and the ambient light can expose the image. The gradient in this image from bottom right to top left clearly shows why the auto white balance in the camera can not adjust to this situation. There is not one uniform light color for it to adapt to and correct. You can also see how the histogram is all over the place even though this is just a photo of a white wall. The fourth image was taken with a 1/4 CTO placed over the flash and the white balance in the camera shifted from flash to florescent, this is because the flash is now pretty closely blended to the ambient light of the room which is pretty close to the florescent preset. 

Image 3 and Image 4
Image 3 and Image 4

Looking at the histogram we can tell it has not been perfectly balanced, but an exact balance is not possible with gels. At any rate it is much closer now the color is no longer painful to look at with only minor corrections needed in the computer. Corrections which can be applied across the whole image rather then trying to blend in different layers of correction, a much more difficult task. 

For these last two images I raised the flash to above the eye line as that is more typical for portraiture, as a result the gradient shift from the third images is seen here in the fifth images from top right to bottom left. The fifth image gives an idea of how difficult it would be to correct the color balance in the computer rather then only needing a minor adjustment to the over all white balance of the sixth photo taken in a close color balanced situation. The complete chaos in the histogram of the fifth image gives a clearer picture, even though the scene is very color neutral the histogram is all over the place.

Image 5 and Image 6
Image 5 and Image 6

All six of these images were shot on a the Canon EOS 6D camera with the 24-105 f4 L. The lens was set to 58mm the camera was set to ISO 400, f8 and a shutter of .4 seconds with the exception of the second image which had a shutter of 1/180th of a second to crush out the natural light. The flash was located 45 degrees camera right and was set to manual 1/32 power 14mm.


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Sunday, August 11, 2013

HDR


High Dynamic Range is a method of merging photographs to capture all of the visible scene in one image. HDR is only needed when the dynamic range, the difference from light to dark, is greater then the camera’s image sensor can capture. Many of todays cameras have a dynamic range of around 11 stops, the human eye has a dynamic range of around 14 stops. For this reason it is common to see photos where the landscape has a good exposure but the sky is blown out and has lost its blue color and all of the detail in the clouds, or the sky is in perfect exposure but the landscape is dark, lost in shadow. Using HDR to merge photos of differing exposures allows a person to create a photo that has detail visible in both the sky and the landscape.

Many of todays cameras have a built in HDR setting which removes the need to have software capable of merging the images for you, though software gives much greater flexibility in exactly how the images are blended. For instance on my Panasonic DMC-ZS10 point and shoot the HDR setting is a Scene function of the cameras automatic setting, as such I have no control over the aperture or shutter speed of the camera. On this camera when I use the HDR setting there is a slight lag to the shutter, the camera holds the shutter open creating an image out of the data captured. In this manner an image is created with a wider dynamic range then the camera would otherwise be capable of.

On the EOS Canon 6D the HDR functions more like it would if the photographer were to preform the image merging on computer in post production. The 6D has an HDR function that operates as part of the manual settings on the camera and can operate in M, P, Av, and Tv modes. On this camera when HDR is set you meter for the mid-tones and then select an exposure compensation value of either 1, 2 or 3 stops when the shutter release is pressed the camera quickly takes three images one exposed for the mid-tones one under exposed for the highlights and one over exposed for the shadows. The camera then creates a single image out of these three files.

In both of these cases software in the camera is attempting to mimic what can be done on computer in order to capture a wider range then the sensor normally would. Before digital HDR did not exist but other methods were employed to capture a wider dynamic range, HDR is an extension of those techniques. In the days of film when a photographer needed to capture a wide dynamic range a gradient filter would commonly be used to stop down the sky so that it was closer in exposure value to the landscape. If further correction was needed the developer of the film could selectively dodge and burn the film to lighten some areas and darken others. Gradient filters can also be purchased in blue or orange to better match the tint of the sky or sunset.

As photoshop and digital manipulation started to advance as a tool it became possible to capture a wider range of information then had been possible on film. Most film has a dynamic range of 4 or maybe 5 stops, this was particularly important in studio lighting and is where the 3/2 lighting ratio for subject and a background 2 stops brighter then subject (when you wanted a white background) come from. When you have a total of 4 stops it became critical to keep the lighting in a narrow band. The early digital sensors also had a very narrow band of sensitivity, however they had one distinct advantage over film. With digital it is possible to take several images at different exposure values stack them up and merge them into an image with a dynamic range of 10, 20 or even 100 stops if that were necessary. The spectacular images from Hubble are examples of HDR taken to extreme limits.

The other option that is available to digital is similar to the dodging and burning of the negatives during development. This is the use of RAW files, I mentioned above that many modern cameras have a dynamic range of 11 but there effective range when generating 8 bit Jpegs tends to be closer to 8 stops. By shooting in RAW and exposing for the highlights (this is key as anything lost in the highlights is lost) a photographer can then go into the file on computer and use RAW processing to pull up information that is being lost in the shadows. From this file an 8 bit Jpeg can then be produced that fully utilizes the 11 stops the camera has.

Now that we have spent a lot of time on what HDR is and where it comes from I am going to give a brief run down on how to do it. If you are about to ask why I am not spending more time on the how too, that is because it is about to be surpassed by technology, I mentioned that many cameras are already capturing 11 stops, they will soon be capturing more stops and in greater detail then the eye can see, as the greater demand for high definition moves forward the 8 bit format for Jpeg images, computer displays and printers will be surpassed by 16 or even 32 bit formats and the need for image stacking will again slip back into the realm of astronomy where it is being used to capture massive amounts of data that is not available in visible light. I have some confidence that this prediction is correct, in that, 8 years ago to get a good HDR image it required stacking 5, 7, or even 9 images to get a wide enough range of exposures. Now three images will allow you to use the 11 the camera captures plus 2 stops (or three if you use a 3 stop interval) below and above giving a rang of 15 (or even 17) stops.

So now we have an idea of what HDR is, how does it all work? I brushed over that above in that you take pictures with different exposures. The setup up is really quite simple though the blending on computer (the post) takes a bit more practice. To take the images you will need a camera and a tripod. It is possible to make an HDR with the camera set to auto (in some cases) by using the cameras exposure compensation settings to get the ver and under images, but it is best if you are comfortable shooting in full manual mode. Once the camera is on the tripod the image is framed and the focus has been set, turn the auto focus off (if you did not focus in manual) take your first images metered for the mid-tones then use the shutter speed to adjust down 2 stops, so if your mid-tones were shot at 1/125th then your shadows will be shot at 1/30th and then adjust up two stops above the first image to 1/500th to shoot your highlights. 

If you are using an older camera and need a wider range you could also shoot down an additional 2 stops at 1/7th and up two more at 1/2000th, but if you are using a fairly modern camera (made in the last 3 years or so) then you really wont need to. Once you have the 3 (or 5) images you will merge them in Aperture, Lightroom or Photoshop - depending on your software you may need to find an additional plugin to do this.

When is HDR used? HDR really is best used in situations where the dynamic range is too great for the camera and modifying the light is not practical, several examples are sunrise/sunset photos, landscapes, cityscapes, architectural photography, things that are too big to effectively light AND the dynamic range of the scene is greater then the camera can capture. If you are looking at a scene and the camera can capture the image without an clipping occurring in the histogram HDR is not needed.HDR is not really practical for subjects that move, portraits, pet photography - anything like that it is much better to correct the lighting before the image is taken then it is to try and get 3 or more images where everything but the exposure is the same.

Image created with HDR
Image created with HDR
This first image is an HDR composite.

















The three following images are the multiples used to create the HDR shot at 2 stop intervals 


2 stops underexposed to get highlights
2 stops underexposed to get highlights

Exposed for Mid-tones
Exposed for Mid-tones

2 stops over exposed to get shadow detail
2 stops over exposed to get shadow detail



This last image is the scene as the camera wanted to capture it using the auto setting














Comparing the first to the last it is possible to see how HDR both allows a photographer to capture a wider range and how close camera is getting to making HDR an unnecessary art. If you wish to explore HDR in more depth I suggest looking to the works of Colin Smith




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Sunday, August 4, 2013

3 Point Lighting

3 Point Lighting
3 Point Lighting

3 point lighting really should be looked at as the fundamental building block for all lighting in both photography and video. I do not make this statement as a judgement, in no way do I mean that the light setup shown here is “the best”. The best light is what is need for the image being created. But what I do mean is that these 3 aspects are present in all lighting setups and need to be considered whether you are using one light mounted on the camera or a 20 light studio set. In all lighting cases you will be working with and should be thinking in terms of Key Light, Fill Light and Background Light, your three fundamental lighting aspects. All other lights, hair lights, rim lights, kickers are just added fluff used to better define how the light falls on the subject and how the light separates the subject from the back ground.

A little bit of house keeping - the camera used was the Canon 6D with the 24-105 f4 L lens, the camera was located 6 feet from the subject on a tripod set to ISO 200 f8 1/160. The lights used were Canon Speedlites set to manual the background light was the 600EX-RT and the Key and Fill lights were both 430EX-IIs all three lights were set to manual. I include this information because a lot of people do ask about it - but really the equipment is not important, understanding how it is being used is what matters. If this is your first article on lighting I would suggest also reading Lighting Your Subject and Part II as well as looking at the resources linked in those two posts.

Key LIght
Key Light
Key Light, the Key Light is the main light in the lighting set up. While the methodology of studio lighting can seem intimidating when you first approach it the Key Light is really the only light you need to really understand. As long as you get the Key Light correct everything else really just slides into place. The Key Light is the main light falling on your subject and is also commonly referred to as the subject light. The Key light sets the direction and quality of the light in the image and in general will provide the mid-tones to highlights of your subject in your image. I say in general because not all photos use the full tonal range. Your Key Light will determine your exposure settings, even if you are wanting a very high key image with the background blown out you will determine exposure based on how your key light falls on your subject. In the example shown here the Key Light is a Canon 430EX-II set to camera right at 45 degrees from the subject, slightly elevated at a distance of 1 1/2 feet and sett to 1/16th power and 14mm.







Fill Light
Fill Light

Fill Light, in many ways the Fill light functions much like the Key Light but instead of defining the mid-tones and highlights it defines the shadows. While light defines your subject the shadows define the mood of the image. In the example shown here the Fill light is a Canon 430EX-II set to camera left at 45 degrees from the subject, placed at the same hight as the subject, at a distance of 1 1/2 feet, set to 1/32nd power and 14mm. Generally a Fill Light will be set somewhere between 1 and 3 stops lower then your Key Light, however there is no correct way to set it - there is only what is correct for your vision, let your vision guid both the placement and the intensity of your Fill Light. I frequently work with the fill light mounted on the camera or even set as far around the subject to be at 180 degrees from the Key Light. If I want the lighting to be quite flat the Fill will be set to almost the same power as the Key, maybe only 1/2 stop lower or if I want the image to have a lot of drama I may turn the Fill off.





Background LIght
Background Light
Background light, the background light does exactly what it sounds like, it lights the background. If you go back and look at the previous two lighting articles linked above you will notice that the background is lit by spill coming form the Key Light in those examples, in some cases it is lit quite a lot while in others there is very little light falling on the background. By adding a background light you can gain control over how the background displays in the image. The Background light was a Canon 600EX-RT placed directly behind and below the subject, gelled blue, at a distance of 12 feet from the wall, set to 1/4 power and 28mm. As you can see the background light is set considerable higher then the other two lights. This is not a hard and fast rule, it was what was need to get proper illumination of the background.

Above I mentioned that as long as you have control of your Key light all of the other lighting will slide into place. The background light can be the best example of that. In the images for the articles linked above the background light had not been considered at all. Only the manor in how the light fell on the subject was taken into account, whether or not the light also happened to spill into the background was not thought about or corrected. The easiest way to control spill is with  light fall off, by placing your Key and Fill lights as close as possible to your subject and turning the power down while moving your subject as far as possible from the background you can prevent most spill, the other option can be to use a flag (dark fabric or panel) to prevent the light from traveling in an unwanted direction.

In this post you can see that I have created 4 distinctly different images without changing any of the camera settings or even recomposing the shot. The important thing to take away from this blog entry is get your Key Light right. If you think about it all four of the above images were set and determined by the Key light, yes even the silhouette is set up by first determining the Key light. For that image I want the Key Light output to be zero and the Fill light to be less then that. Once I have a dark image I then just mix in the correct amount of Background Light to match my vision. That is exactly what happens with every other light whether you are shooting with one or 100, set the Key and then just mix the other lights in to the intensity and direction to create what you envision.

If you look at the images in An Introduction to lighting Your Subject you can see an example of how one light can be used to control all 3 aspects of lighting, all 3 points. It also helps demonstrate why the Key light firing from the camera directly at the subject is bad, it ends up functioning as fill and background light and there is no practical way to control all three aspects. However simple by turning the flash and bouncing it off of a nearby wall or ceiling you can then gain control not just of how that flash functions as a Key light but how much fill it provides and how it falls on the background.


** As an aside the lighting set up shown here is an excellent way to display products, I highly recommend it for your eBay photos, it is also a good place to start with lighting people for portraiture though for portraiture you want to pay a lot more attention to exactly where the Key light is positioned in relation to your subject and their pose. In both cases pick a background color that compliments the subject.




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