20 August 2007

Flash chase

It's been a while. If you still bother to check this blog once in a while, you have my humble thanks, and my deep respect for your persistence.

Thing is, there hasn't been much photography in my life lately. Not much of an environmentalist twitch either. Hope to rectify both in weeks to come.

What I have for you today is a humble test of a piece of flash gear. I've envied other people's macro shots taken with ring flashes for a long time, and have figured it's time for me to acquire one too. However, it tends to mean a lot of money, so I've been on the lookout for cheaper options.

Over at B&H, I came across the "Digi-slave flex-ring 6400". A solution that purported to be a very flexible and decent solution. Instead of using ordinary strobes, the Digi-slave use LED technology. On the manufacturer's website, it is advertised as "super-bright" and "perfect for any kind of close-up photography".

At face value, this appealed very much to the environmentalist within, since the light yield per inputted power is traditionally very good with LEDs. But are they truly powerful enough to replace flash strobes? Well, this unit has 64 of them, and could be worth the try. So I shelled out USD 350 to B&H, and received it a couple of days later.

Would you like the conclusion first?

Here goes.

After some initial testing, I now know that this is not the unit I was looking for. It will nonetheless be very useful, but I'll get back to that.

What was I expecting?

When shooting macro with flash, I work without tripod. I use flash sync shutter-speed, typically 1/180 or 1/125 seconds. I also want to stop down a lot, say f/22 or f/16. My macro lens is a 200mm, with a working distance around 40 cm for a 1:1 subject size factor. My expectation was for the Digi-slave to provide enough light to illuminate my shots at ISO 100 or 200.

What did I get?

This unit will emanate enough light for an exposure of f/4.5 and 1/180 second at ISO 200 and a working distance of 40 cm. That's just puny. This unit is unsuitable for field work with insects and other moving critters.

How can this unit be used?

To use f/22 at the same EV as described above, you'll need an 1/8 second exposure. So, obviously, this unit is for situations where you don't need fast shutter speeds. Like flowers (at still. Don't breathe hard...) and inanimate objects.

Personally, I will put this unit too good use when winter comes, to photograph snow crystals and other frozen water shapes. I expect this unit to excellent for the purpose because the LEDs release very little heat, which is essential for frozen water photography.

Is it worth the money?

If your primary application is real field work; no. Not at all.

With inanimate objects like jewelry, flowers, etc., it might be a different story. For me, as a nature photographer, the price is too steep for the limited use I can put it to. I wouldn't have bought it had I known what I know now. The lingo used to market this unit is stretching the truth, in my opinion, beyond recognition. The wording around the superlatives is exactly imprecise enough to ward off accusations of untruth, as it does not cite anything that is positively wrong. They are even careful to omit insects from their list of typical examples of macro subjects. To call it "super-bright" and "perfect" is way beyond, though. And come to think of it, there's a conspicuous lack of reference to guide numbers.

[slaps forehead] No Guide numbers?!? Duh. I should have known better.

1 comment:

Cymen said...

I am glad you reviewed this piece of equipment but I had preconceived notions it would be as you concluded. All is not lost with LED ring lights though as the newer very powerful LEDs can provide much more light than the older models. But they are also much more expensive and produce more heat.

Hopefully, we'll see a P-TTL ring light from Pentax one day!