Flash 101: On-Camera Flash

Lisa's note: Things have been a bit busy at the Jeff and Lisa household lately, which explains the lack of posting. Things should be back to normal soon though. To the new subscribers, hi! Welcome to Beyond Megapixels. Feel free to browse through the popular posts, and the rest of the archives. With that out of the way, enjoy Jeff's article on the basics of flash photography.
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There are two ways for you to use your flash: on-camera and off-camera. There are pros and cons for both and we’ll tackle the biggest ones here to get you started on flash photography. Before I forget, when you go through other websites you might wonder why they use the word strobes rather than flash. It’s the same thing so don’t get confused.

ON-CAMERA

In Part 1, we will be discussing On-Camera flash. When on-camera flash is mentioned, the first thing that comes to most people’s minds is the tiny flash unit found in point-and-shoot cameras and entry-level DSLRs. What we’re referring to in this article are external flash units mounted on a camera's hot-shoe.

PROS

1. No red-eye. Since external flash units are about a half a foot away from your lens, the chances of red-eye happening are slim to none.

2. Portability and mobility. No don’t need to bring anything but your camera and flash unit. You also don’t need to move around to adjust the settings on your flash since it’s right there. You have flash capability in a moment’s notice.

3. Bounce your flash. Most external flash heads allow you to swivel it from left to right and up and down. This gives you the ability to bounce your flash to make the light hitting your subject softer and more flattering. Take note that if the surface of wall or ceiling you are bouncing from is not white then the light hitting your subject will have some tinge of the surface color

CC Photo by Okko Pyykko
4. ETTL metering. Electronic-Through-The-Lens or ETTL refers to how your camera meters a scene. It basically measures the light as it goes through your lens. Dedicated hot shoe flash units can make use of ETTL metering when it calculates how much flash is needed to properly expose your subject. This feature saves you a lot of time if you’re just starting out in flash photography since you don’t need to fiddle with the intensity of your flash.


5. Fill-flash mode. Fill-flash refers to the flash just giving off enough light to make sure there are no harsh shadows on your subjects. What happens is that your camera measures the ambient light and properly exposes for this while telling the flash to expose for the subject. Some manufacturers require you to activate fill-flash mode either in your camera or on the flash unit while some like Nikon and Canon automatically defaults to fill-flash when there’s enough light in the background.

6. Focus assist. Built in flash helps in auto-focusing (AF) by throwing off small bursts of light when ambient light is low to help the camera focus. This is really annoying and in my opinion could induce epilepsy. External flash units assist in auto-focusing by throwing off red light which is very faint and non-obtrusive. Below is a photo of the focus assist lamp on the Canon 430EX II.

CONS

1. Full-frontal light. The reason why on-camera flash photography looks so unnatural is that the light source is noticeably coming from the camera. This is not how we regularly see our surroundings unless you walk around with a flashlight attached to a helmet on your head. This problem is being slowly addressed by manufacturers by making complex algorithms to balance flash and ambient light. You can also try swiveling the flash head as mentioned above but that only works when you’re near something to bounce the light on which isn’t always the case.


CC Photo by trentroche
2. Shadows on the wall. As a rule of thumb, you should avoid using flash when the subject is near a wall since you will mostly likely end up with the subject’s shadow on it.


CC Photo by Beige Alert
3. Flash fall off. Flash fall off refers the situations wherein the subject was properly exposed by the flash but the background is completely dark. This is due to the simple fact that you cannot light the entire background with your flash unit.


CC Photo by Dawn Ashley
The most important thing to know when purchasing an external flash unit is that you need to make sure to buy one that works with your camera. A lot of bad things can happen if you place an incompatible unit on your camera’s hot shoe. If you're lucky then the only thing that could happen is that the flash will not fire but there have been incidents where either the flash or camera short-circuited. In our opinion, it’s better to buy one that’s the same brand as your camera.

Ready to take your flash photography to the next level? Stay tuned for part 2 when we discuss off-camera flash.

Related Reading:
How To Get Soft Diffused Light From Your Flash

Filters 101 (Part 2)

You can read the first part of this article here.

•DENSITY FILTERS

Density filters are like sunglasses that you would wear on a sunny day. They effectively darken the scene and are available in different strengths. The most commonly used type of density filter is the neutral density (ND) filter since it does not add any color cast. Density filters are necessary if you plan to capture motion blur on a bright day. Without it, the extended exposure necessary for capturing motion blur will cause you to blow out your highlights.

CC Photo by MmMmMmMatt
Landscape photographers use a specialized type of density filter called the graduated neutral density (GND) filter. A GND filter is shaded at the top part of the filter and slowly fades until the bottom of the filter is clear. This filter was designed to darken the sky in a photo without affecting the foreground. The two most popular GND filter variants are soft-step and hard-step filters. In soft-step filters, the transition between the shaded part to the clear part is very gradual and subtle which is good for horizons that are not completely flat. Hard-step filters have a more defined boundary between the shaded area to the clear area.


CC Photo by ccdoh1
GND filters are also available as both the threaded and the square filter version. It is better to get the square filter GND so that you can adjust exactly where the transition of the shaded to the clear area will be.

There are a lot of techniques in Photoshop that emulates the effect of a graduated neutral density filter like the one found in our previous article. Photoshop will only help accentuate what detail you managed to retain in the sky and not save a blown photo.


•POLARIZERS

Polarizers come in two variants: linear and circular. These variants do not refer to the physical shape of the filter but how it directs the light coming into your lens. Linear polarizers direct light waves into a linear fashion while circular polarizers direct light into a spiral or circular motion.

The only important thing to remember when buying a polarizer is that linear polarizers do not work with DSLRs or cameras that have the ability to auto-focus and auto-expose. This means that you have to focus and fix the exposure before you attach a linear polarizer to the lens. Circular polarizers, on the other hand, can be attached to the lens during metering and auto-focusing.

Polarizers darken the sky, the greens in the foliage and cut reflections in your photo. In my opinion, this is the filter that does the most for DSLRs. Polarizers attach to the front of the lens much like any other filter with the addition of another rotating element at the front of the lens. The rotating element at the front is what controls the amount of polarization. You can look through the viewfinder and see the amount of polarization while you rotate the filter.


CC Photo by OliverAlex
The effect polarization is also dependent on where your camera is pointed. The effect is at its maximum when the camera is aimed perpendicular from the rays of the sun. If you’re out taking photos at noon then the amount of maximum polarization would be at the horizon. Polarizers will exhibit no effect if it is aimed at the sun.

You should also use caution when using polarizers with wide angle lenses since the amount of polarization is different across the sky. Some parts of the sky will appear bluer than the rest if the angle of view of your lens is too wide. The photo below was taken with a lens set at 10mm. You can see that the sky is bluer at the center of the photo where maximum polarization is present.


CC Photo by J.Rosario

SOME NOTES ON FILTERS

1. Filters, not just density filters, will lessen the light entering your lens since it adds another element for the light to pass through. Be sure to check the specs of your filters to see how much it affects your exposure.
2. Filters will not affect how sharp your photos are unless your filter is dirty.
3. You can stack filters on top of each other to mix their effects. The rule of thumb is that you can use three filters at the same time before the quality of your photo is affected. Be sure to double check your lens’ manual if this holds true for you.


RELATED READING:
Filters 101
How to Fix Washed Out Skies

Filters 101

Filters are basically tools to modify the quality of light hitting your sensor. They used to play a more integral role in photography before digital cameras came along. Nowadays, a lot of people discount the importance of photographic filters thinking that they can replicate any effect they want during post-processing. This is not entirely true. There are some filters that can never be replicated on the computer no matter how good you are with Photoshop.

There are literally dozens of filter types available in the market today that can cause a first time buyer some confusion.This article will discuss some of the most basic and important types to help get you started.

FILTER MOUNTING

Filter mounting refers to how the filter attaches to your lens. The two most common filter mountings are threaded and the square filter system. Threaded filters are circular in shape and just screw on directly to the lens. Square filters require a filter holder to attach the filter to the lens.

Some types of filters, such as the protect filter, are available only as threaded filters while some like gradient filters are better used in their square form. These will be discussed further in the article.

FILTER SIZE

To find the filter size that's needed for your particular lens, you need to look at the front of the lens with all the marking on it and look for the symbol in the photo below.

CC Photo by William Hook
Different lenses have different filter sizes. This means that one size will definitely not fit all. To avoid having to buy the same filter for each type of lens you own, we suggest buying converters or step-up rings. Step-up rings allow you to attach a threaded filter that has a bigger size than that of your lens. The photo below is an example of a B+W step-up ring that attaches to a lens with a filter thread size of 72mm to a filter that is 77mm.

FILTER TYPES

• UV / PROTECT FILTERS

Protect filters do just that, protect your lens. It is basically just a clear piece of glass that screws on the front of your lens to protect it from dirt and scratches.

UV filters block ultra-violet light in a scene which can cause your image to lose some sharpness. Does it work? I have no idea. We’ve been taking photos for a very long time before we attach a UV filter to our lens’ and I have yet to notice a difference in image quality. We mainly use UV filters to protect the frontal element of our lens much like what a protect filter will do.

• COLORED FILTERS

Colored filters are classified by Wratten numbers with each number corresponding to a specific hue or color. The system was named after the Frederick Wratten who established a company in the early 1900's specializing in filters. You can see a listing of Wratten numbers with their specific colors here. These types of filters add color to the scene. The most commonly used colored filters for photography are warming and cooling filters. You can try the Cokin 81 series filters to warm up a scene or the 82 series filters to cool it down.

The practically of colored filters have gone down with digital cameras. You can get the same effect by playing around with your white balance setting. Check your camera’s manual on how you can enter a specific color temperature for white balance so you won’t be limited by the usual presets of daylight, shade, etc.

• CLOSE-UP FILTERS

Close-up filters are the way to go if you don’t want to spend on a dedicated macro lens. These filters enhance your lens’ magnification power by lowering the minimum focusing distance so you can move much closer to your subject. The filter’s strength is measured in dioptres with the weakest being +1 and the strongest at +10. Your lens’ focal length will also determine the magnification factor. For example, an object will appear larger if you use a 100mm lens with a +3 dioptre as opposed to using a 50mm lens with the same filter. The photo below is a close-up filter set from Hoya.


Of course the image quality will never be equal to that of a macro lens but close-up filters are still a lot better than cropping during post processing.

(To be continued...)

RELATED READING: How to Protect Your Lens