Speedlights, brollies and zooming flashes
If you’ve used a Speedlight then you’ll have spotted the zoom setting which can be used to make the spread of light from the flash match the angle of view from your lens. When it comes to on camera flash that’s great news as it helps to maximise t
he efficiency of the flash but go off camera and it’s something that can easily get over looked. Setting the zoom for off camera speedlite work is one of the handy tools in a photographer’s bag of tricks. It can be used to shape the light into a tight rectangle or spread it wider and rounder. Most speedlight’s even have a pull out diffuser for a crazy wide spread of light. So what should you do with the zoom setting when you’re shooting your flash into an umbrella or softbox? In a nutshell I tend to zoom out to the wider end of the flashes zoom range but I wanted to see how things changed at different zoom settings so I did a little experiment. 
Let’s start with the side view. At my Canon 580EXII’s maximum zoom of 105mm the flash is diffused fairly well but it’s noticeably bright in the centre with a lot of fall off at the edges. Things don’t change much even at 50mm zoom but by 24mm zoom the light spread from the umbrella is a lot more even. Flip out the wide angle diffuser and zoom reads 14mm, now that’s wide! The resulting light is amazingly soft and diffused but it’s so wide it actually passes the edges of the umbrella completely! 
It’s the front view which probably make things clearest. The hot spot at 105mm to 50mm is clear to see. At 24mm the flash coverage is better but at 14mm it’s very VERY even. So what conclusions can I draw from this? Well the obvious one is don’t zoom the flash when using an umbrella or softbox. 14mm looks very tempting but one thing to note is the flash power was roughly a stop less than at 24mm. So I’ll be sticking to 24mm for my brollies but I might consider going for 14mm in softboxes when I can accept shallower depth of fields or higher ISO in my photo.
- Related:
- flash
- photography
- speedlight
Greetings Gavin!
Thank you for the great post. I recently watched a video by the legendary Joe MacNally where he uses a diffusion dome through a shoot-through umbrella to have a softer spread of light. In fact, he almost always employs diffusion domes when using Speedlites. http://youtu.be/h25IURGFv9M?t=5m37s
My question would be whether this technique would theoretically would be an improvement in power (since you do not need to mechanically zoom out within the Speedlite), whilst still benefiting from from a dispersed light spread through using the dome? The diffusion dome would still eat up some of the flash power, of course.
Cheers from Canada!
Nice idea but I don’t think it will help with the power too much. Full power is full power, zooming simply squeezes it into a tighter cone. Adding a diffuser will help spread the light but it will always cost some power. Sounds like a good idea for another test/blog post 🙂
I would certainly be keen in reading about it and particularly how this would apply in real world conditions with a subject.
PS – my apologies in my initial post and the over usage of the word “would”; I was too caught up to proof-read before posting. 😉
Thanks Gavin, another great little tutorial, love ’em!
Hi Gavin,
Did you see similar results when using a more reflective umbrella rather than a shoot through?
I don’t use reflective umbrellas to often but I would expect the advice to be the same… go wide but not crazy wide.
What about using a more zoomed flash to concentrate the light forward but extending the brolly away from the head so that the light hits the whole surface? Would that give the softness but with more power? Or just make the stand fall over!!
Lol, falling over is always a worry but some umbrella holders will also slowly drop with the weight.
Zooming the flash doesn’t give it extra power it just squeezes the light into a smaller area at a given distance. There’s also the inverse square law to consider when backing off the light.
Best practice is to ensure maximum coverage of the umbrella but not to the point of going beyond the span of the modifier.
Gavin,
Great post. I just recently purchased a pair of radio triggers and a soft box. I’ll be experimenting with zoom settings this weekend.
Maybe an umbrella like westcott apollo octagonal, with its diffuser, helps…
Yes it does but to avoid hot spotting you want to the speedlight to fire a wide beam of light… or shoot with bare bulb flash 🙂
Gavin, what do you think about octagonal (and large) umbrellas with diffusor and internal aluminum coating? May this solve the “zoom” problem?
Yes and no. It will help spread the light but you’ll still want the speedlight to produce a wide beam to start with.
I’ve seen (but I don’t remember the model) an umbrella like the octagonal one, with diffuser, but the speedlight stays on the normal hole on the back and there is a reflective cap so the light bounces twice…
Hi Gav. Great post, you are always a mine of useful info, your generosity knows no bounds. Jus tgrabbed hold of a couple shoot throughs and stands, can’t wait to test them out. I now have a good understanding of brollies. I thought to use a ttl cable to lessen the height of the speedlight and radio triggers, thereby getting a more central beam to the brolly. Maybe attaching it to the side of the light stand with a bungy cord you know the type that we use on a bike rack, I would appreciate your thoughts on the idea.
Hello Gavin.
Your examples how to use speedlights are great. I’m taking pictures just for my pleasure but I would like to improve my skills.
I saw in your videos that the light from speedlight for example on 105mm create narrow and bounded spotlighted space which looks like rectangle. I would like to create the same, but I’m not able to do it. I have set my speedlight on 105mm, 135mm and also on 200mm, camera D750, 1/200, F8-F16, ISO200, but always the light is spread in very large space. Yes, the center is visibly brighter and from center to corners the light decrease but I never get shaped rectangle of light.
Maybe there is a diffence in construction between Canon and Nikon speedlights. I have Nikon SB-800 and you use Canon speedlights. I saw the same effect (shaped rectangle) in videos on Youtube. Also with Canon speedlights. But i’m not sure that this is the right consideration. I think that the problem is in my hands. 😉
Could you be so kind and tell me where I do mistake? Thank you in advance.
It’s hard to say what’s going on with having your light in front of me. Assuming the speedlight is actually zooming (you’ll hear a motor working as it zooms) and you DON’T have the wide angle filter over the head, there should be a rectangular sort of shape to the light although different flashes will give different effects.