1. I read about guide numbers, and how to work out what aperture you should be shooting with your camera, you divide the distance the light source is to the subject by the guide number eg. if your flash head with a guide number of 80 ft is 8 ft away from the subject, then you should be shooting with a camera aperture of f/10. Correct?
Actually you divide the guide number by the distance to arrive at the aperture. You need to be aware that there are two different ways of expressing guide numbers, metres and feet - but the answer is the same, whether you divide the distance in metres into the guide number in meters or the distance in feet into the distance in feet. Guide numbers are measured with a specific lighting modifier (e.g. a standard reflector) and at 100 ISO and (should be) measured in a space that's large enough for ceilings and walls not to inflate the figures.
In another (slightly confusing) tutorial I then came across the phrase "measure your flash aperture" and couldn't figure out whether measuring flash aperture was the same as the above (measuring what aperture to set your lens to for correct exposure with external flash heads using guide number and distance) or whether this was a separate thing altogether?
There are a lot of tutorials on the interweb that I don't understand either.
Maybe s/he was talking about using a flash meter.
2. Will it be easy to get good lighting with two shoot through umbrellas as compared to softboxes? I have read your studio lighting theme guides Garry and you mention that shoot throughs aren't much different to softboxes, so I guess it's just more to do with my familiarity with softboxes/complete inexperience with umbrellas more than actually thinking that softboxes are significantly better than umbrellas. This is because I have been at a couple of studio shoots where the photographer used two large softboxes, at around 30-40 degrees either side of the subjects and achieved some good results with them, whereas I've never seen umbrellas being used and would feel more out of my depth with them!
Shoot through umbrellas have the
potential to produce similar light qualtity to softboxes simply because they can be placed as close to the subject as softboxes can, this is different to reflective umbrellas because reflective ones face the wrong way. But this doesn't matter to you, because for this job you won't be able to place them close anyway - so reflective umbrellas are a much better choice than shoot throughs, which will scatter light everywhere.
Umbrellas are very portable and very cheap. Softboxes would be fine too, but they are neither portable nor cheap and I feel that ones big enough for your purpose may be outside your budget.
3. Regarding lighting positioning. I mentioned in No. 2 above about seeing a photographer (in an identical setting to the one I have been hired to do - full length shots of couples or groups up to 10 people in front of a 3m wide backdrop) use two large softboxes 30-40 degrees either side of subjects and slightly elevated (perhaps 7-9 ft high?). The results of that shoot came out pretty well and I thought to myself to use the same set up. Now some more people have recommended that set up to me, whereas others have told me to avoid it like the plague as if it is a really bad way to do things. This has made me very confused as to where to put the two lights, especially the fill flash, as some people have said to go with the above example, someone else said the fill flash should be behind the camera, elevated to 12 ft and others have recommended other conflicting positions etc etc... Any help?
The lighting arrangement you describe is known as 'event lighting'. That's a perjorative term but this type of lighting does actually work for this type of shoot.
The advantage of 'event lighting' is that it's extremely easy to set up and to get consistent results and there isn't a big problem with shadows from one person getting on to someone else's face. The disadvantage is that the lighting is bland and everyone ends up with a fat face, but that is the accepted standard for event photography.
A lot of people get confused about fill lighting. A fill light is a light that illuminates ALL of the subject as seen by the camera, therefore it has to be on axis with the lens, either immediately above, below or behind the camera, never to one side.
But don't worry about that. What you need is one light each side and a bit above for your purpose, and set at equal power, even though one light each side wouldn't cut it for portrait photography (unless you believe what you read in some camera magazines)
A better arrangement, if the venue is suitable, is to have one light with an umbrella off to one side and above a bit and to bounce the other light off of the white ceiling, using a standard or high intensity reflector. But of course, for that to work, you will need the ceiling to be both white and low enough.
I can vouch for the fact that the lencarta kit is 'awesome' and does everything I need and has plenty of power, don't let Garry's understated support deflect you from the fact that they should be a serious consideration.
You can spend less, you can spend a lot more, but I'm not sure you can get a better price/quality balance
Thanks for that Keirik, yes I suppose I do understate. That's just my personality (or lack of it)
I try to be even-handed and I feel that I can be, simply because I've tried out most of the equipment that's out there. The problem is, there are a lot of people posting on forums who wax lyrical about the 'qualities' of their own kit, when all they are actually doing is quoting the suppliers' sometimes untrue statements and they don't actually have any basis for comparison.
I think it's called human nature...
