Showing posts with label ETTL. Show all posts
Showing posts with label ETTL. Show all posts

Sunday, 24 August 2014

USING SPEEDLITES FOR BETTER RESULTS


Speedlites , simply stated, are accessory flashes that attach to the hot shoe of your DSLR. By raising the light source above the camera, the speedlite produces a more pleasing effect than the harsh head-on shadow cast by the camera’s built-in popup flash.

But there’s more to speedlites than that. Most have swivel heads that allow you to “bounce” the flash off a ceiling or wall to provide a more diffuse light source. This has the effect of softening the shadows behind the subject and more evenly filling in shadow areas on the face. Because the flash head is now well separated from the camera body, you can also add light modifiers such as a collapsible softbox. As the name implies, it softens or diffuses the light, allowing you to aim the speedlite directly at the subject rather than depending on a bounce surface. Outdoors in daylight, these are often used as a “fill” light to overcome the harsh shadows cast on the face by mid-day sunlight.

Better yet, speedlites have their own internal battery supply, so they can be separated from the camera and used in the same way as studio strobes. By mounting them on light stands and firing them with inexpensive radio triggers, you can have studio lighting anywhere, without the need for AC power. Add lightweight bounce umbrellas to diffuse the light evenly, and you can have as many light sources as you like filling an area with even, soft light.

So how do you configure this portable studio? Most of the small stuff can be bought on eBay much cheaper than at local retailers, but bulky items like light stands and umbrellas, in my humble opinion, can be sourced locally for not much more than overseas online pricing. And you have the benefit of not having to wait 2-3 weeks for product.

When it comes to speedlites and radio triggers, however, I would like to make a recommendation. While I want to stress that I have no affiliation with the company, I have found products made by Yongnuo of China to be well made and very cost effective. Just be sure that when you make a purchase that the models you choose are designed for your specific DSLR model. In some cases, their triggers are also compatible with camera manufacturers’ speedlites, but why not buy a speedlite that works as well at a third of the price?

So what is a radio trigger? If you decide to use a speedlite off-camera, you will need a means of making the flash fire when you press the camera’s shutter button. The transmitter mounts on your camera’s hot shoe and sends a signal to the receiver, which you mount on the light stand. The receiver has a hot shoe built onto it, so you simply attach your speedlite to it. Some triggers, like the YN-603, are actually transceivers, so you can use them as either a transmitter (when mounted on the camera’s hot shoe), or a receiver (when the speedlite is attached to it).

Now, there are two types of speedlites that you should be aware of: manual (such as the YN-560 III) or full ETTL (such as the YN-565 EXII). ETTL stands for Evaluative Through The Lens, meaning the camera and speedlite work together through connections on the hot shoe to ensure that the light output from the speedlite gives optimal exposure.
YN-560 III in off-camera configuration

A manual speedlite, however, requires that you set the light output on the speedlite itself by either trial-and-error or by using a flash meter. Studio setups are typically all manual. The YN-560 III has a very nice feature: built in radio receivers that are compatible with the YN-603 trigger. This means that you only need a single YN-603 on the camera’s hot shoe, rather than also attaching one to each of the speedlites to act as receivers. One feature of a manual flash is that its hot shoe connection is comprised of only a single contact point. This makes it compatible with a wide range of cameras, as opposed to an ETTL speedlite that has an arrangement of multiple contacts that are specific to a camera brand. This is why you must buy an ETTL speedlite specifically for your camera.
 
 

Yongnuo also makes an ETTL radio trigger called the YN-622. Two of these transceivers will allow you to trigger a compatible off-camera ETTL speedlite like the YN-565 EXII in full ETTL mode, meaning you don’t have to manually set the speedlite output. The camera reads the light from the speedlite through its lens and sends commands to the speedlite over the YN-622 radio link to adjust its output. You can also control groups of speedlites with these so that each has a different output level, but still controlled by the camera.

YN-565 EXII operating ETTL through a YN-622
Another benefit of using the YN-622 and a compatible speedlite on the camera is that you can use that speedlite in ETTL mode while simultaneously triggering a manual flash with a second YN-622 off-camera. That way, you can quickly move from a studio setup with two lights to a roaming subject using the single ETTL speedlite on your camera (such as in a wedding reception). The YN-622 simply attaches to the camera’s hot shoe and the speedlite attaches to the YN-622’s hot shoe.


Stacked YN-603 on a YN-622
While the Yongnuo product line is great value for money, however, I get the sense that the company doesn’t have a uniform design vision. For example, the built-in trigger receiver in the YN-560 III doesn’t exist in the YN-565 EXII. Where this becomes an issue is if you want to use the 560 and 565 together in a setup (with the 565 set to manual mode) and trigger them both from a single YN-603 trigger on the camera. Also, you can’t mix and match YN-603 and YN-622’s in a setup because they’re not compatible. You can, however, stack one on top of the other on your camera’s hot shoe and have each trigger their respective receivers.
By doing a little research, you can configure a professional lighting setup for well under $500. Just be sure that you are buying product that is 100% compatible with your camera make and model

Thursday, 6 February 2014

WINTER EXPOSURE


Have we had enough of cold and snow yet? Unfortunately, it doesn’t look like it’s going away any time soon.

So – if you have the itch to get out and take some photos anyway but are disappointed with the results, the problem may be with exposure. The photographic kind, that is. The camera meters (measures) the light coming through the lens and tries to ‘average’ the exposure to a mid-grey (referred to as 18% grey).

With Evaluative (Canon-speak) or Matrix (Nikon-speak) metering, the camera reads the light over several zones in the viewfinder. If a bright scene covers most of these zones, the computer in the camera will calculate the exposure based mostly on these bright zones. In winter scenes – guess what – snow tends to dominate the scene and the camera tries to expose it to a mid-grey. So, if your winter shots are a little dark, that’s the reason.

There are two fixes for this: spot/partial metering and exposure compensation. I find the latter is the easiest solution so I’ll address it first.

 
Exposure compensation is a means of overriding the camera’s metering, by allowing you to over- or underexpose by an amount chosen by you. It’s normally controlled by pressing the +/- button and turning the command wheel on the camera. As you do, a bar graph (depends on the camera) will indicate by how many stops you are changing the exposure.

Since the snow caused your camera to underexpose, you need to dial in some overexposure or + exposure compensation. I typically use about one and two-thirds stops, but you may need to use something different depending upon how much of the scene is occupied by snow. Just don’t forget to dial it back to zero when finished, because it won’t go away when the camera is turned off.
 
Partial or Spot metering relies on something that has a mid-grey tone (although it can be a colour like facial skin) centred in the viewfinder. It effectively ignores all the white snow around it and exposes based on the face or mid-grey object.

I hope this helps, because there’s nothing I can do about the weather. If you need a little more help,  check out my photography courses at www.filmscapes.ca

Wednesday, 8 May 2013

Meter this.

We’ve all seen the portrait photographer holding a white-domed object next to the subject’s face to take a light reading. So why is that being done? Why not just let the camera do its automatic exposure thing and take the picture?



 


It’s a good question in this digital age, where we can instantly review our shots to see if we need to re-shoot with a little exposure compensation. After all, the histogram in the camera tells us just about everything we need to know about the exposure in the shot – is it under- or over-exposed and is the exposure evenly distributed over the entire tonal range?

The short answer is that the handheld meter is mostly used to measure the light falling on the subject from studio strobes or flashes mounted off-camera.  In this scenario, the camera doesn’t typically have the ability to control the flash output, as it does in ETTL mode when the flash is mounted on the camera’s hot shoe.  Hence, studio photographers usually work with the camera in manual exposure mode, where they manually set the shutter speed to a value that will synchronize with the flash and the aperture to a value that gives the correct exposure. Alternatively, they can use the  meter reading to set the brightness of each flash in a multi-light setup to give a particular effect while ensuring a proper exposure.

Here, I’ve used the words ‘light falling on the subject’, meaning incident light. Hence, the incident light handheld meter measures the ambient light and ignores how much light the subject is likely to reflect.  The metering system in our camera, on the other hand, does rely on the light reflected from the subject to determine exposure.

Which is more accurate? The incident meter is, because it is calibrated so that it will give camera settings to make an 18% grey card look like 18% grey (middle mark on the histogram) when photographed.  The reflected meter, however, relies on the subject's tone averaging out to 18% grey in order for the exposure to be accurate. If the subject is overly dark or bright (such as a snow scene), the reflected meter gets fooled because it tells the camera to expose as if the subject is mid-grey. The incident meter would read the light falling on the snow rather than the light reflected from it, thereby resulting in the snow looking like bright white snow rather than grey slush.

I started out stating that the incident meter is used in the studio to measure the light from strobes or flashes, but obviously it has a function in outdoor ambient (continuous) light photography as well. Some photographers work in manual exposure mode all the time and therefore rely on an incident meter for camera settings.

So why bother? Part of the answer may be a throwback to the film days, where you never knew until it was developed whether you got the exposure right or not. An incident meter (and a little exposure  bracketing) gave you the confidence that you got the shot. That way of working may still influence the photographer who has made the transition to digital, partly because it’s good practice.

The bottom line, though, is that anyone seriously considering turning pro using studio lighting setups should consider working with a combination flash/continuous incident meter, if for no other reason than to save time. The alternative is to shoot, tweak, shoot and then tweak some more.

Combination meters can be a bit of an investment, so they’re not for everyone.  If you’ve got the spare change, though, a meter can help you understand the exposure mystery a little better and hit the bullseye every time.

Thursday, 10 January 2013

Fill Flash: Balancing Ambient Background and Subject

I've often ranted in my courses about how horrible mid-day light is for photography. Apart from the colour temperature concerns - an overly bluish, cold tinge to the light - harsh shadows cast from overhead are unflattering, particularly on human subjects.

The flash, either the built-in pop-up variety or the accessory hot shoe type, can assist if you are forced to shoot in the daytime outdoors. Weddings fit this scenario. Turning on your flash to shoot outdoors may seem absurd, but pros use it all the time as 'fill flash'. The word fill refers to the fact that the flash illuminates the face to fill in shadows in the eye sockets and under the nose and chin. Photographic Botox®, as it were.

The modern digital SLR does its best to balance the ambient outdoor light and the fill flash through ETTL (evaluative through-the-lens) metering. ETTL uses a number of different points on the image to determine what the correct exposure setting (ie. aperture and shutter speed) should be, and controls the output from the flash to properly illuminate the subject.

As brilliant as the microcomputer in the camera is at doing this, results can sometimes be other than expected. Let's say the background looks properly exposed but the subject looks a little dark. If you have a strong backlight, this may mean re-positioning your subject. If that's not possible, you can adjust the flash output, independently from the camera's exposure setting, by using flash exposure compensation.

Accessory Flash Exposure Compensation
There are two ways you can change flash output. The accessory hot shoe flash will allow you to adjust output using either the buttons on the flash itself OR through the flash exposure compensation setting in the camera. Depending on the camera, either the camera's flash exposure compensation will be used or the setting dialled into the accessory flash will be used: they cannot be used in combination. For the built-in pop-up flash, you can (obviously) only use the camera's flash exposure compensation setting. So, for the underexposed subject, set the compensation for, say, +2/3 stop and try again. The subject should brighten and balance with the background. 

Exposure Compensation button on camera
For the opposite scenario - the subject is properly lit by the flash but the background is too dark, you can use exposure compensation to control the background exposure. This is different from flash exposure compensation in that it controls the choice of aperture and/or shutter speed but not flash output. For a dark background, dial in a positive number, and for an overly bright background, dial in a negative number. You may have to tweak the flash exposure combination again to get the best result.


Negative Exposure Compensation plus
positive Flash Exposure Compensation

So, by setting flash exposure compensation and exposure compensation independently, you can achieve a balanced image.

Let's leave the mid-day scenario and think about doing a portrait just after sunset ('magic hour'). Using aperture priority or shutter priority modes, the camera's metering system will try to expose the twilight sky properly before lighting your subject with the flash. If the subject looks overly bright and unnatural against the sky, you can balance them by using negative flash exposure compensation or a bit of positive exposure compensation, or both.

The results from doing so will amaze you. After all, the pros adjust their light sources to balance them against the ambient light.