Quick update - guide numbers and grey skies...

Hi guys.

Just a quickie to show you all an image from today’s Bridal shoot all the way down south in Yarloop. I’ll keep this one short as we will be posting some more images soon – once I have had the opportunity to actually have a good look through and pick out some of my favourites from the 400+ images we took today.

So the image you can see was taken in a paddock that was vacant and had a “For Sale” sign on it – a good candidate we thought as it was unlikely that anyone would worry about us being there.

As I said this is only a quick post – but I wanted to briefly share one thing. Today I took out with us my newly acquired Bowens GM250 monoblock studio strobe heads. I picked up a couple of these as part of a whole packaged kit by Bowens from a colleague and fellow photographer of mine. They had very little use and I got them for a very reasonable price. Awesome.

The main reason I got these heads however was to give me something smaller and more portable (and also a helluva lot cheaper) to use on location, rather than the Bowens GM500 monoblock heads that I also have. The GM500 heads are awesome but I am always very wary of taking them out of the studio – mainly because these puppies are so expensive and I really do rely on them for our everyday studio shooting requirements. What I am trying to say here is that I can’t live without them! But would the GM250 heads be able to put out enough light in a location photography environment?

But anyway, getting to the point... I was really impressed with the power output of the GM250 heads. They have an output, or “guide number” of 54. It’s a pretty exact science but it roughly translates that at 1 metre distance from your subject they will put out f/54 @ ISO100. For comparison, the GM500 heads have a guide number of 80. For the geeks out there, the next two paragraphs may interest you...

“The guide number for an electronic flash measures its ability to illuminate the subject to be photographed at a specific film or sensor sensitivity and angle of view. A higher guide number indicates a more powerful flash.

For example, doubling the guide number means the flash can illuminate an object at twice the distance, or for an object at the same distance can be used at one quarter the sensitivity. Doubling the guide number requires a quadrupling of the flash's power, as the area to be illuminated increases as the square of the distance. (cf. inverse-square law).”

Easy right? So far as to say the GM250 heads didn’t skip a beat. Yes it was overcast and most of the time we weren't shooting over about f/9, but we also kept the flash about 5-6 meters away from Tanya (our model) the whole time. And the really best bit – I was using the Bowens Travel-Pak battery to power the heads. This thing is rated to give you 200 full power “pops” of flash when using a 500 watt/second flash head at full power. We took 400+ shots today, mostly at around ½ to ¾ power on the GM250 heads. At the end of the day, the battery indicator on the Travel-Pak was reading >75% power remaining. Fantastic.

Gotta go. Keep shooting what you love and we’ll catch you soon.