Tuesday, January 5, 2010

DIY Flash Gel Holder

This gel holder is an easy and free way to use the Rosco gels (like these) on any flash.

Just take the semi-stiff, clear, plastic that comes as a part of so many things that you buy these days and cut it into a rectangle that's about 3 times as wide as you flash head and about 2 1/2 times as high.

Then fold it approximately (but not perfectly) in half so that it's easier to separate the two pieces to swap the gel out while it's on the camera. Next, match it up to your flash head -put the flash head in the middle, then fold the plastic so it fits the width of the flash head perfectly. When folded, it should look like this:

DIY Gel Holder, Unfolded

A rubber band on the end of your flash will allow you to tuck the tabbed ends of the flash holder under the rubber band on either side to hold it on your flash like this:

DIY Gel Holder, On Camera

Just make sure the opening on your folded gel holder is pointing up so the gel doesn't fall out. But, this design allows you to swap the gel in and out as needed.

DIY Gel Holder, Swapping Gel

Using gels for color correction with flash.

The situation is similar to my previous article -I have a model in a room. She's inches from a white wall and lit by a normal overhead light fixture that has a 60W tungsten bulb in it.

Because she's so close to the wall, the overhead light creates a shadow on the wall to the camera's left (her right).

Our eyes generally adjust for the yellow/orange cast of tungsten lighting so we don't even notice it normally. Similarly, if we put our camera's white balance on "Tungsten" then our camera can adjust for the color balance too. (Auto white balance can be hit or miss.) So, if we take a photo without flash it'd come out just fine as far as the color is concerned -we could just adjust for it.

But, if we add a second light source by taking the photo with flash, this is what you get:


Notice the unusually blue-colored shadow areas. Why did that happen? Well, it may help to turn the white balance to "Daylight" in order to see what the photo looks like when the tungsten light isn't corrected for:

Uncorrected color cast

Note that the room light (the yellow/orange tungsten light) is creating those shadows because the light from the tungsten light isn't reaching those areas. Then, when we use flash we're adding light to the whole scene INCLUDING those shadowed areas. But the light from the flash is white while the room light is that yellow/orange color. So, uncorrected, what you see is a lot of yellow/orange cast with normal gray shadows -because the flash filled those in, they don't have the same orange tint to them.

Then, if we correct for the orange cast with a white balance setting in our camera or in software after the photo's been taken -here's what actually happens: Remember the color wheel? Opposite of orange is blue, so to make orange go away, the computer adds blue to it. If we add enough blue for the background to look white, the same amount of blue is added to those already neutral gray shadows, so they look blue! ...so now we know why we got the results we did for the first photo, and we can work on fixing it.

What we need to do is to make all of our light sources the same color. That way, when we correct for the tungsten light the shift towards blue doesn't make our shadows blue. So, if we put a yellow/orange gel on our flash, here's what we get (after color correction):


Pretty neat, huh? All you have to do is gel your flash so it matches the light in the room. If it's tungsten light, then use an orange gel. If it's fluorescent light than you'd usually use green. Trying to color match yourself can be hit or miss, so gels are sold that match your average tungsten and fluorescent light perfectly.

Saturday, January 2, 2010

Lighting techniques

Many times when shooting an event or while at a family function you'll be called upon to take a photo of a person or group against a wall; so this a good project for beginners to practice. I'm going to walk you through one sample situation and we'll discuss some different ways that you could take the photo and their good and bad points. Note that this is part one of a two part article. This part will discuss quality of light only. The next article will discuss the color of the light. You'll notice that there are different color casts to the example photos included below -please ignore them for now. I want to tackle one issue at a time so, for now, we'll be focusing on the quality of light only.

Okay, first let's talk about the situation. You're being asked to take a photo of one person against a white wall with a window to the camera's left (the model's right). The window has blinds on it so you can close or open them as you see fit. Outside it's bright, but cloudy so the light's fairly nicely diffused by the clouds, but since it's on the model's right side, it only lights half of her face. Overhead there is a 60W tungsten light bulb in a fairly normal (slightly diffused) ceiling fixture.

Here's a diagram:
Setup for model shots

If you close the blinds and take a shot using only the room lighting (the tungsten bulb) here's what you get:
Overhead tungsten bulb only
Note the fairly well-defined shadow under her nose and lips and also on her neck due to the lighting from above. Also, the light's not catching her eyes well since her brow is blocking most of the light from above.

If you open the blinds to allow the light from the window in you get this:
Overhead tungsten plus diffused side-light from a window
That's softened the shadow on the neck and under the lip, but it's created a shadow from her nose on the left side of her face and we really want more light on the left side too.

To get more light on her left side, we'll grab a reading lamp with a 100W equivalent daylight-balanced CFL in it and put it to the model's left (camera right). Here's the result:
Window side-light w/ lamp to fill shadows
Wow, the lamp is brighter than the window light, so now we have sharply defined shadows from the lamp on the model's right side from her chin and nose!

Perhaps we can tone down and diffuse the lamp light by putting something in front of the bulb? Let's try a piece of copy paper held in front of the bulb pointed at the model:
Window side-light with diffused lamp to fill shadows
That softened the shadows on the face nicely. The shadow on the neck's still there, but I'd call this acceptable!

But what if there was no such reading lamp? Perhaps we could try flash instead? Here's one using the on-camera (pop-up) flash:
On-camera (pop-up) flash
Whoa! That's harsh -check out the highlights in the hair, under the eyes, on the chin, and the sharp "chinstrap" shadow on the neck. This isn't very flattering light, it needs to be softened a LOT!

So, let's try putting something in front of the flash to help disperse the light better. A tissue or a paper towel would work, but all I could find was some toilet paper. Let's try to make due with that -I folded it a few times, then put it over the flash and here's the result:
Pop-up flash diffused w/ toilet paper
That toned the highlights down, but only slightly and the more we diffuse the flash, the less light we get out of it and the worse the shadow under the nose will get due to the overhead light.

So, let's try a more powerful flash. Below is the result of attaching a Canon 580EX flash on ETTL and aimed directly at the model.
Canon 580EX flash on camera pointed at model
Not too surprisingly, just like the pop-up flash, the 580EX straight-on is too harsh.

Let's try attaching one of those cheap $5 diffusion caps to the flash head (keeping the flash pointed directly at the model):
Canon 580EX w/ $5 diffuser cap pointed at model
Well, that diffused fairly well -the highlights are softer, but there's enough light to soften the shadow under the nose too. The shadow on the neck under the chin is still quite dark and well-defined, though.

Let's try taking the diffuser cap off and pointing the bare flash bulb at the ceiling instead.
Canon 580EX flash on camera pointed at ceiling
Wow! That did a great job of getting rid of that "chin strap" effect of the sharp shadow on the neck under the chin! There's enough shadow to show definition, but they are soft so they aren't distracting. I'm counting this one as a keeper.

I have one more thing in my bag I'd like to try, a Lumiquest Pocket Bouncer. Let's attach that and try it with the default white surface.
Canon 580EX with Pocket bouncer using white surface
Hmm... chin strap is back. The rest of the shadows look good, though.

...this article was really to spur some discussion, so feel free to comment here, on the individual photos on flickr, or on the mailing list. I'd be happy to try other techniques and take more sample photos as well as explain the how's and why's of the above photos if you have questions. Otherwise, stay tuned for part two of this article where we'll discuss white balance and the how's and why's of using gels on your flashes.