Portrait photography

[DrunkenZombiee]

So I have been to lots of Black tie and White tie events over the past year where a photographer has been present and taking portrait shots. Having looked at the shots they have taken with fixed equipment (dual flash set-ups with umbrella diffuser having taken light meter readings) set up I have been very unimpressed with the outcome of the shots, they all are devoid of colour on the face however blemishes somehow seem to be amplified (don't know how they managed this), with the background also in focus! NASTY!. Granted these were taken at night and outside with a nice background of a garden or bit of architecture.
I have been far more impressed with the un-posed free roaming shots taken often without flash at higher ISO with automatic metering enabled.

I have been asked to take a few "posed" shots by some friends to celebrate their 5 year wedding anniversary which they will get blown up onto canvases, some of these will be indoors or at night and the fastest lens I have is my 50mm f1.8 which is not IS and getting to around 1/80 of a sec with only ambient light and up may be difficult. Are all of the rules of thumb to do with exposure when using flash and light meter readings the cause of these nasty photos by professional event photographers?

Are there any tips that you can give me to avoid this, other than not using flash with or without a diffuser.

DZ.

[smilodon]

There's lots of stuff you can do to make nigh time portrait photography a 'relatively' simple process. I'm sure there are some others here who (based on their Flickr pages) take a mean portrait shot as well who can add to the discussion. I'm a amazed anyone actually uses light meters any more. You already have a very good one in your DSLR so why use another is beyond me unless there are some very strange lighting set up's that might fool a built in meter?

The thing that confused the hell out of me for ages was the idea that your shutter speed isn't really important when using flash at night. What controls the exposure is aperture and flash output power, rather than aperture and shutter speed as in 'normal' daylight photography. All you need from the shutter is for it to stay open long enough for the flash to fire and the sensor to capture the image. The fastest shutter speed you can use will depend on your camera but should be around 1/125 to 1/250 second. Don't set it faster than that or you'll get very odd results. And as you will hopefully be setting aperture to control depth of field it will be the flash power that determines the exposure, or at least it will be your variable setting. If you're looking to get some clear background detail then the shutter speed will play it's part. Think of the shot as two exposures. one comes from the flash and will expose for the main subject and the other comes from the shutter speed and will expose for the background. often with night portraits you'll ignore the background as you want it dull and underexposed so it doesn't compete with the main subject.
 
So with the 50mm 1.8 lens (which is going to be great for portraiture set an aperture that will keep your subject in focus but blur your background. This isn't a set f stop so you might want to experiment but f2.8 - f4.5 is going to be close. I'm not sure what your camera is and if it's a Canon I don't know the settings at all but set your flash sync speed for something like 1/60 second which should be good for a hand held shot with a 50mm lens. You can more or less leave these settings alone now if your shooting portraits. What will vary will be shutter output. If you're shooting from the same location then you can set a flash power manually and stick to it as people will be standing in the same spot for every shot. However if as I think you said you will be moving about then set the flash to 'TTL' mode. This will allow the flash to use the cameras light meter to fire a quick preflash, meter the shot and then fire the main flash as the shutter opens. TTL is usually pretty decent but I find it sometimes shoots too bright and so dial it down by a stop.

However what will make your shots look less than great is that flash is a very hard direct light and isn't flattering at all. It's a spotlight that casts harsh shadows and bleaches out fine features. This is why in a studio you'll see people using huge diffusers to soften the light (I've even used  white bead sheet once). The bigger and less directional the light the more it wraps round a persons face and produces a much softer creamier light that can be very flattering. So it's worth adding a diffuser to your flash gun. There are quite a few cheap options from companies  such as Lumiquest (my favourite). This softer light will really flatter your subjects.

Also try to set the ISO as high as you can without adding noise to the shots. the higher the ISO the less hard the flash gun needs to work to get the shot (flashguns can read a cameras ISO when in TTL mode and will adjust their power accordingly).

In TTL flash photography the process runs something like this.

You focus and hit the shutter.
The flash fires a low powered preflash
The cameras light meter reads the exposure and sends the details to the flash.
The flash works out what the required flash power is for that specific shot.
The shutter opens and the sensor begins to collect light from the scene.
The flash fires and the light is record on the sensor and exposes your subject correctly.
The shutter closes, usually within a 1/60 of a second.

hope this helps a bit?


I've posted even more waffle here
http://www.deadmen.co.uk/forum/showthread.php?33053-Photography-102-flash-guns

and here
http://www.deadmen.co.uk/forum/showthread.php?33142-Photography-202-flash-guns

[DrunkenZombiee]

Cheers Smilo,

I think the main problem is the diffusion of the light, as I am a bit of a bokeh master with most of my shots being as low f-stop as possible but these all have been during the day. I will rig up some kind of diffuser for the built in camera flash, as I am using a non TTL flash gun which does seem to overpower everything on a very low setting.

Will let you all know the results.

DZ.

[suicidal_monkey]

There are some fun things you can do with slower shutter speeds too, to capture movement, both with and without flash.