Tuesday, 19 October 2010

Unit 205, Speedlites and other flash equipment

In this post I shall be talking about flash and flash equipment, 

To start with I shall talk about my two Canon Speedlites, a 580 EXII and a 430 EXII. The 580 EXII is the flagship flash gun in the canon range, it has a guide number of 58, the guide number is the numerical measure of the flash guns power, so the guide number of 58 means that it can correctly expose a subject 58 meters from the camera with a focal length of 105mm. As this is top of the range flash gun it has all options possible to start with It can swivel 180 degs in each direction of it's horizontal plane and 90 degs in its vertical plane, (it can also deflect down by 7 degs which is suitable for close macro shots. it has a flip up diffuser panel for use with ultra wide angle shots and a white card reflector, again this is flip up to aid fill flash and catchlights when bouncing light.

On the technical side this flash is able to use high speed strobe flash up to 1/8000 sec when fitted to my Canon 5D MKII, which is well beyond the cameras shutter speed of 1/200sec, this is particularly useful when I want to use fill flash in sunny high contrast conditions conditions. it also has a slow sync mode which is the opposite end to the high speed mode whereby the shutter is kept open longer to record the ambient light  then using the flash to freeze any movement, this is also called dragging the shutter.  Sometimes when you use slow sync you get a blur in front of the subject so this flash has the ability to change the timing of the shutter to what is called rear curtain sync, this make the flash go off at the end of the exposure rather than the beginning, in this way the blur is then behind the subject creating a more pleasing result particularly with moving subjects. It has flash exposure compensation which can be used to decrease the flash output in fractions of a f stop, just as you would if you were adjusting your ambient light exposure compensation on a DSLR. this speedlite has the ability to be used a master flash by sending a infrared transmutation to another (slave) flash, This option is a redundant feature for me because I use wireless transmitters and receivers with the speedlights set on manual. The most important thing in my opinion is that the flash gun can be used totally automatically when mounted on top of my camera, this achieves constant results due to it's TTL capability, this is known as through the lens metering and is the way in which the camera and flash work together to properly expose the image.

There are various ways to use flashguns when mounted on top of  the camera, the obvious first choice is to fire the flash directly at the subject, this is OK when you are in harsh sunlight and you are wanting to give some fill to the shadows, but in any other situation the light is too harsh and is not flattering to the subject.  So what do you do there a two options, whilst on camera, you diffuse the light by fitting such things a Stowen diffuser which gives ok lighting, I prefer to bounce my light off an available wall, making sure the wall is white or cream as this will give a colour cast to the subject, or use a  reflector to bounce off.

To achieve better more flattering lighting it is better to get the flashgun off the camera by using a hotshoe 1.5mtr cable, obviously this has range limitations, the benefit is that you can still use TTL capability I prefer to use my wireless transmitter on the top of my camera and transmitters connected to the hotshoe of my Speedlites.this gives me the freedom to use my flash on manual setting up to 30 mtrs away through walls, I would use this to full advantage by positioning a flash inside a car to illuminate the interior or to create side lighting and better modeling light, or by using two one behind creating rim lighting.

My other Speedlite, a 430 EXII has almost identical operations and controls but hasn't the capacity for a master wireless control, slave only and has less power of 43 mts and 105mm focal length.

Another benefit of wireless/ remote flash is the option to paint with light, this is a process where you have a long exposure and then illuminate parts of a scene with multiple triggers of the flash, such as in in one of my previous blog entries of the car shoot in complete darkness.
What I have been trying to do with my car shoots is to mix ambient light with balance flash exposure, such as when I was photographing my Kia.

There are limitations to Speedlites, mainly power output, so what other option is there? the solution is to use studio flash units, all of them use mains power supplying them, and some have the option of connecting a separate battery power pack which of course give you the option of taking then almost anywhere. The College have some of these portable lighting outfits and these are what we will be using on my car shoot, just like on my trial run with the equipment with Eric's car in another of my blogs.

The units that the college have are the Bowens Gemini 500 kits, each kit comes with a sizable carrying case with castors, a single flash 500 watt monobloc units a silver reflector brolly, lighting stand and battery pack and all cables that I would require to do the job. The flash unit controls consist of two power dials on the side, one to adjust the power in full stop 1-5 and the second in tenths of stops, a red LED to indicate the power level situated between them. As I will use a flash meter to set my exposure it will be quite easy to adjust the flash instantaneously in tenths of stops. on the rear you have to usual on off switches, and also one to change fro unfortunately you don't have the option to use the modelling light whilst using the battery, I assume this is to save the battery life. Again I will be using my wireless receiver/ transmitters so I won't have to worry about trailing cables or pulling flash units mains to battery over. The battery pack is reasonably compact with carrying handles, an on off switch, power indicator and cable terminals points, you have to make sure when using one flash per pack to fit the blanking plug to create a connection otherwise it would never work. the flash units have a sturdy bracket with a large knurled knob to adjust the angle of the unit whilst fitted on the stands.

The other alternative to studio strobe lights is continuous lights, these light are just like a fluorescent low energy lightbulb, no flash of light. They are very easy to use as they a continuous you can see exactly where the light is falling and to what intensity. these lights produce minimal heat and are balanced to daylight colour and are naturally softer than flash. The down side is that because they cannot be a intense as strobe flash your shutter speeds may suffer.

the reason I will be using strobe battery powered flash is obvious, as I have the option to use the college units and are better than my Speedlites.

Next installment..... Lenses

1 comment:

  1. Hi Jim
    as usual you technical detail, etc with kit is spot on and very detailed and targeted well to criteria.
    Your label system is very comprehensive and will allow you to achieve a high grade on this course, again.