Using gels to correct light from flash and match ambient

For once this isn't a product related entry, but I hope it will still be of some interest to read.

I was shooting a charity burns supper the other night in a local hall. Quite a large location, probably about the size of a basketball court in total. About a quarter of the hall has a second level with seating, which was unused for the event, so I took advantage of a quiet location to shoot from, not to mention a more interesting angle than down below.

As soon as I arrived, I metered the hall and found it to be a typically dull 1/40s @ f/4, ISO 800. Worse than that, it was an even spread of very high up lamps leading to a lot of nasty downward light giving pretty unflattering shadows on everyone in the hall.

I grabbed the organiser and the band together and checked flash would be ok, and as soon as they confirmed they didn't mind, I disappeared upstairs to set things up. The first step was to get some control on the light. I found a bit of white painted wood and took a quick shot of it. At a glance I could see it was a very orange photo, which confirmed what I already thought - these lamps were producing light which was relatively close to tungsten balance. A very slightly fluorescent green was also noticable, but so little I didn't feel the need to balance for it. I'm guessing these were the large mercury vapour style lamps you often get in large buildings. The green cast is easily sorted when processing the raw files (pick a tint between which takes an average of the slight difference), and saves the flash needing to fire much harder through two filters than one. Had it been like some mercury vapour lamps I've come across which give a very green image when set to tungsten white balance, I'd have had no choice but to add a fluorescent gel.

I instantly deleted the test image out of habit, but I managed to find a wide angle shot I'd taken with available light, and cropped in on a white table setting. You can see how orange it appears with a daylight white balance setting.



Once set to tungsten, the colour casts all but disappear, at least to an extent which is good enough for what I needed.



Having established that I only needed a CTO gel to balance for tungsten light, I stuck it on the flash and hooked the flash up on the wall. This little decorative thing proved a useful place to stick the flash. You can see the gel attached on the front of the flash if you look carefully. I also zoomed the flash fully in to 105mm to give the best throw of light given the size of the hall.



Here's a shot which shows the CTO gelled flash firing with the camera set on tungsten and daylight balance. Lets you see how important balancing the flash is for decent looking images.



With the flash balanced to tungsten, and my camera balanced to tungsten, I was free to shoot from anywhere in the hall and have plenty of clean "white" light. I was now shooting at 1/250s @ f/5.6, ISO 1250. A much safer exposure given I was including ambient light, but as you can see, I'm now underexposing the ambient a bit from my original metering when I arrived. Adding up the numbers, you can see my shutter speed is 2 1/3 stops darker, my aperture 1 stop darker but my ISO 2/3 brighter. This means I'm underexposing the ambient light by 2 2/3 stops making that part of the exposure pretty dark, and therefore it won't make a huge difference to my images if I get any camera shake when using a longer lens (I was getting some close in shots on the singer/band etc.). The flash exposure, even with a fairly high power, will be faster than 1/700s which is plenty fast enough to give sharp images. The ambient light is providing some subtle fill though which is what I wanted. Why have I opted for a higher ISO speed? Well, it saves the flash having to work so hard, and a well lit image always hides noise that much more than a poorly lit one. Also gave me a touch extra depth of field to work with given I was able to stop down a little.

You can see the flash is easily powerful enough at this high ISO speed to fire right across the hall and light the far wall a good 50-60 feet away. It is also giving a subtle fall off in the curtain behind which helps when I'm taking shots of the band. Gives a nice vignette look to the image.



Here's a shot I took from the left of the balcony where it extends out across the hall a bit. You can see where I was at the left border of the previous image. From here, the light is close to side lighting the band, which gives a nice contrasty image, with my ambient exposure combined with reflections from the wall opposite the flash serving to control the contrast.



Here's a shot where I fired off a second shot too quickly and the flash didn't keep up. It gives you a feel of how I've underexposed the ambient and I'm really only using the flash to give my exposure.

Product Photo: Electronic Device with screen

Sometimes taking a photograph of a product just isn't enough. You have to show what the product actually does. In the case of an electronic device with a small screen, such as an mp3 player (in this case a Sandisk Sansa Express 2GB), the screen will not likely be very bright. Using flash to take a photograph of a device such as this therefore becomes a matter of balancing the flash light with the ambient light (the screen).

First, we need to see what exposure we need to get a decently bright looking screen. Just a matter of trial and error till you find it. In this case, I got an exposure of 1/15s @ f/5.6, ISO 400. This unfortunately means that the lights on the ceiling above are starting to come into play which normally isn't the case with flash product photography. You can see that the orange background I'm using has been lit darkly by the ceiling light.



This problem is swiftly dealt with by switching off the ceiling light so it doesn't mess with the exposure. Unfortunately this means working in low light with just the light from another room shining in so I can see what I'm doing.

Next step is to light the background. I decided before hand that I wanted to use the background to draw attention to the product, so I wanted a streak of light across the background right behind the product. To do this, I used a snoot on a flashgun and fired it across the background, such that it shines up the back of the paper.



Not quite where I want it, so I adjust the snooted flash a bit to the left so the streak appears higher in our image.



That's pretty well sorted for the background, so now it's a matter of lighting the actual product. I got a small gridded softbox that I've made and used in previous product photos I've posted here, and positioned it just to the left of the product shining across the front.



This proved a little heavy. You can see it's over-lighting the controls, and given we'll want to show up the screen, this isn't very helpful. Not only that, but the background shows a bit of a dark stripe where the light from the softbox is creeping in right at the bottom. To fix this, I moved the softbox further left and further back. This means the spill will be more evenly across the background, leaving the lower area a little touch brighter, and the product will show only the slightest hint of side lighting to pick up the shapes and contours of it.



This is starting to look the part, but you'll notice the product name and the lower edges of the controls are orange. This is because the softbox is lighting the orange paper below the player which is then reflecting up in the shiny edges. To sort this, I get some white reflectors. One goes underneath the player so rather than orange, the reflections become white. The second one is to add some fill to the edges on the right to bring out a little more of the depth of the control layout.



That's much better, and just about how I want it. The only thing left is to take a version of this shot which has the screen switched on. Having played with the player, I knew there was a menu option named "Music" which was kinda cool, and I thought was a good choice of screen to show.



With a bit of PS aided magic, the jack plug and clamp which support the mp3 player disappear, leaving the mp3 player floating. Now you start to see better why I opted for the stripe on the background.



Here's a couple of setup shots for you to look at

Photographing a large paper sheet

Once in a while you get landed with the job of photographing something which would be better off scanned, but due to the size of it, or design of it, photographing it is far more practical. In this case, it was a rather large A1 plan. While I can't show you the actual plan due to the contents not being mine to pass on, I can show you how it was done.

So what do we need for a shot of the plan? Well, there are some fold marks on it, so the most important thing is to get these as flat as possible. Having done this, all you need is very flat, low contrast, non-directional light. Any directional light will show up as highlights or shadows at the creases.

I set up two diffusers to the top and bottom of the plan. You'll notice if you look at the following image that they are angled away from the plan. If they were angled over the plan, there'd be more chance of getting worse highlights on the creases. The diffuser in this case the white diffuser from a Portaflash 5 in 1 Reflector set, supported by a Portaflash 5 in 1 Reflector Support which attaches to any light stand. Because I like them, and they're inexpensive, I used a Portaflash Light Stand

A couple of flashes were then positioned on the outside of the diffusers. I guessed at 1/4 power on the 550EX (equivalent to Canon 580EX II) flashes, and was spot on for ISO 400 f/5.6. Because the plan was sitting vertically, I was using a relatively wide angle lens, and didn't really need too much depth of field. I stood to one side and leaned out over the image. The flash is exposing the image, so I wasn't too worried about shaking the camera provided I got a reasonably good framing.



The light wasn't just the diffusers either. Because of the positioning of the flashes, I was getting a lot of fill light from the ceiling, with the exception of the area blocked by me and the camera.



Having got the shot, I brought it into PS and did a slight adjustment to square up the plan in the frame, and that was the job done. The result was just about as good as a scan, except the resolution wasn't too hot. A1 paper is pretty large to photograph with a 10 megapixel dslr (I use a Canon EOS 40D). Given a dslr with 16-25 megapixel, this image would have been every bit the match of a scanner. Still, everything was readable with a 10 megapixel shot, so it did the job.

The other option for improvement would be to pin the plan up, light it the same way, but everything set relative to the plan hanging on the wall and use a longer lens. This would help reduce the slight distortion I saw with the wide angle lens. Not only that, but with a long lens, you could take two or three shots across the plan, and then join them as a panorama style image. This isn't great done with a wide angle as the distortion makes a mess of the joins.

Product Photo: Spirit Level Rule

Sorry I haven't had time to be putting up any videos the last while. I figured I'd put this one up quickly though without a video. Pretty simple setup, so the shots at the end should let you see how to go about it.

Well, first thought for this shot was background colour. I figured something vivid was called for, so I opted for the brightest of the bunch - a nice bright yellow sheet.

Next thought was how I was going to light this. I wanted to get some light deep in that bubble to make it glow well. I opted for a ringlight which I knew would give a good "shadowless" light while showing up the colour of the bubble. I fired off a test shot to see how well it worked.



Pretty spot on for the bubble, brightness wise, but virtually no light comes back from the ruler because it's sitting at an angle. To deal with this, I needed to put some fill from the right hand side. I put in a couple of my small white foamboard reflectors and fired off another test shot.



At least you can see the effect even if it's subtle. The boards were angled to catch light from the ringlight. So I could either boost the ringlight power to get more light on the ruler, but thereby make the bubble overly bright, or I have to add another light source.

I grabbed another speedlight and put on a small softbox and honeycomb on the front. This had a couple of benefits. Firstly, the soft source of light would more evenly light the two reflectors. Secondly, placing it to the left and firing it over the top of the ruler meant I got a little spill on to the background which gives a nicer brighter image. Lastly, the honeycomb meant I'd not get flare from the light source being just off to the side of the shot. So here's the result. You'll note I've reframed the shot to try and give a better composition. The previous shots were purely tests.



Here's a couple of setup shots.

Portable Soft Lighting Studio

Just a heads up to let everyone know the Maplin Portable Soft Lighting Studio is on special deal again at £9.99 - half the normal price - so get in there quick if you want one!