Most photographers today use gel filters at some time or another. They may use them to properly balance a given ambient situation or add the filter to create a special effect to a photo. To take that to another step, photographers may also use gel filters to achieve both outcomes in one shot, balance and special effects. Please, don't get confused, it's not that difficult.
[note: I am an Apple DESKTOP user. I needed a laptop for the shoot. The only available laptop was a Dell. Do not get confused when I discuss post processing techniques that use Apple shortcuts and commands. All of my discussions relate to Apple functions.]
What is a Gel?
Gels are filters that are attached to the front of your strobe. They come in various colors and intensity of those colors. They are usually made of a thin strip of plastic that can be easily strapped, taped, or however you would like to connect the filter to the strobe's head. These filters are typically used to balance the awful ambient of tungsten or fluorescent bulbs.
Tungsten bulbs, the ones typically found in your lamps at home give off an orange tinted light. You may not realize this while in a room since your eyes adjust for this color and your brain tells your eyes that everything looks, well, Ok. As a photographer, my eyes have become trained to notice this type of light. My brain immediately sees this tint when walking into any room lit by a tungsten bulb.
Typically, a photographer would simply set the camera's white balance to tungsten to correct this situation. This is fine if shooting with available light. On the other hand, if you are shooting with ambient and a strobe, the results will not be so pleasing. The answer here is to add a CTO (color temperature orange) gel to the strobe. Since the strobes flash is balanced more towards daylight, it would not match the change you made in camera. Adding the gel creates a nice balanced lighting situation.
Fluorescent bulbs, the bulbs typically found in office environments are those long tubed bulbs. You know, the ones that you love to drop on the ground after they have burned out. Yes, the ones that make a nice pop when they hit the ground. These lights give off a green tint. Again, this tint is not usually noticed by the human eye but the camera is quick to pick it up. Ever wonder why office workers are not the happiest of people on the planet? Some think that it may the green environment that brings their emotional levels down. I digress. Ok, the fix for this is just like that of correcting for tungsten. If you are using a strobe in a photo with fluorescent environment you would simply switch the camera's white balance to fluorescent and add a window green gel to the speedlight's head.
These two gels are the most commonly used in photographic situations. There is one other trick, if you do not have any gels on hand, to correct the disgusting ambient that these bulbs emit. How so? You ask. If you don't have these gels, simply turn out the lights. Then, change your camera's white balance to correct for flash and you're ready to go. Unfortunately, this technique is not always viable. Subjects don't always want to sit in a pitch black room while waiting for their portrait to be taken. It can give off a slightly weird vibe.
Gel for Special Effects
Gelling for special effects is where you can get really creative as a photographer. Take a look at the photograph above. It is that of yours truly. I threw this one together rather quickly. Not one of my masterpieces but it serves as an excellent teaching tool.
First off, you see the handsome fellow engaged at, who knows what, on the monitor. Now, take a look at the total environment of light. The whole scene seems to be balanced pretty nicely. Then you look at my face. It is as if the computer monitor's light is shining right on my mug. You've probably seen this effect in plenty of movies. They have you believe that the light is so powerful that you actually see the letter being typed on the screen, in reverse on the character's face. Hate to break it to you but it is not real!!! I'm not sure how they do it but I will explain how it's done in still photography.
Before lighting anything, I wanted to get a good ambient balance in the room. I didn't want any tungsten or fluorescent ambient so I turned all lights off. There is plenty of daylight shining through so I set my camera's white balance to daylight. The ambient was still pretty dark. I could have bumped up the ISO to the 800-1600 range but wanted to keep noise at a minimum. I went with ISO 200 in hopes of getting a semi fast shutter at an f/3.5. The best shutter speed I could get at these settings was a 1/4 second. Pretty slow but it would work since the camera was not being handheld and the strobe would help to freeze any motion.
I fired off a few frames sans flash to see how the ambient would play out. Everything looked fine. Now it was time to start the "monitor glow effect." Not having a blue gel on hand, I improvised (you know it baby!) with a translucent blue plastic shopping bag, the type of bag you would get a supermarket. You know, when they ask paper or plastic. I folded the bag a couple of times and attached it to the front of the strobe via one rubber band. I set the flash power to 1/64 and zoomed the head to 105mm. These settings would provide minimal light interfering with the ambient and a beam of light that was narrow enough to stay focused on my face. I placed the strobe on the keyboard, aimed at my head and secured it in place with my right hand. The result? Exactly what I had expected. BTW, this whole shoot took about five minutes, beginning to end, to complete. The longest part of this was finding a blue bag in the house.
This part was a bit tricky. After doing all of my Adobe Camera RAW edits, I opened the file in Photoshop. Here, I usually correct any color casting, first. Unfortunately, since the light and color balances are completely conflicting, I had to find another way to correct. I decided to do each part as a layer mask. Correct for the daylight ambient portion, add mask and paint in accordingly. Following that portion of the editing process, I did the opposite for the facial portion of the photo.
I thought that my face needed a bit more blue, which in hindsight was a mistake. I should have left well enough alone. Oh well, live and learn. To add a bump to the blueness, I added a photo filter adjustment layer. I chose the blue filter at 25% and with a layer mask, painted only the facial and hand area. I lowered the opacity slider to 50% and flattened the image.
Something was still bothering me about the overall image. I didn't like the intensity of light on the back of the laptop. It was a bit strong. I had an idea. Usually, if I want to add vignette to a photo, I have a specific workflow to get that desired effect. I used the same principle to add just a kiss of light to the back of the notebook. Read on.
First, I had to duplicate the background layer by hitting Command-J. Once I have that layer, I change the layer setting to multiply. This gives you an underexposed image. Next, I grabbed the shape tool and created a rectangle around the back of the laptop. From there I go to Refine Edge and adjust the settings so that when I delete the selection the result will be a nice feathered transition of light. No obvious deletions. I then delete the selection. The result is a nice kiss of light on that computer. Now, The rest of the photo is still underexposed. To fix that I simply add a layer mask and paint with a black brush, everywhere I don't want to be darker. This was everything in the photo except that computer. Again, I flatten the image. Finally, I add any other tweak that I find necessary, save and call it a day. All in all, the whole project took about an hour. From setting up the shoot until saving as a jpg. I probably took a coffee break somewhere in between. You get the point, once you get the hang of this stuff, it doesn't take too long to complete.
There you have it, the world of gel. There are many more functions of gels but this was a simple lesson to help you understand how and why they would be used. Stay tuned and I will have some more interesting gel lessons. Gelling for mood is one soon to be written blog. Maybe not the next or the next but it will show up eventually.
Until next time...