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Tutorial: Playing with Fireworks (in Photoshop)

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In my last post, I included a composite image of a firework exploding. In today’s post, I’ll explain how I did it. If you’d like to follow along, I’ve included the starting images at the bottom of this post. Simply right-click to download. You can use as few as two images, or all of them, with this method. You will need Adobe Photoshop CC or an extended version of an earlier Photoshop to follow along.

150906-fireworks-0072-edit-1986

The final product! Read below for my methods!

Step 1: Get photographs to composite

To create a composite image, you first need the images to composite! My images are below, and if you prefer to use them, you can skip this section. If you’d like to use your own images, you’ll have to capture them! In this section, I give all the nitty-gritty shooting details; you can also skip ahead if you know how to shoot an exploding firework.

You will need a DSLR, and you will need to know how to change settings like ISO, aperture, speed, exposure bias and your shooting modes. First, fireworks are dim and you will need to make sure your sensor gets all the light it can; I turned up my ISO to 12800 and opened my aperture all the way to f/2.8. (A side note about ISO: your camera may not go up to ISO 12800. My other camera tops out at 3200, and I find the images unpleasantly noisy above ISO 1600. I’ve still taken good fireworks shots with that camera. You may want to turn down exposure bias more than I have, and a tripod is a great asset.) Second, I turned the exposure bias down for several reasons: (1) to avoid blowing the highlights, (2) to allow a faster shutter speed, and (3) because an image of fireworks against a dark sky is a dark image, and a low exposure bias accurately reflects this. I turned the exposure setting down two brightness stops. I shot in aperture priority mode with a fixed ISO and a camera-calibrated speed. You could also fix the speed and allow the ISO to vary. With the settings above, the exposure times were 1/250 sec and 1/400 sec for the nine images. I shot in speed priority continuous shooting mode. I shoot with a Sony Alpha 7s– when shooting in RAW mode (rather than a compressed JPEG mode), it takes 5 frames per second. I took these shots using a monopod. A tripod can allow you more flexibility with your shot settings. I shot these images at a focal length of 72 mm and the Alpha 7s doesn’t have image stabilization, so I wanted my shutter speed to be 1/100 second or faster.

Phew, got all that?

Step 2: Prepare images for composite

Open your images as layers in Photoshop. (Consult this link if you’re uncertain how to open images in layers.) The order of the layers doesn’t matter at all.

The images must be aligned. If you shot using a tripod, you’re probably good. If not, there are two ways to align your images– the easy way and the hard way. If you are using my images, I have already aligned them for you.

The easy way: Auto-Align Layers Select all your layers. Then go to the edit menu and select “Auto-Align Layers”, as in the image below. Select the “Auto” projection in the dialogue box, then click okay. This method will work if there is an object in all the images that Photoshop can recognize and align, say the corner of a building. Sadly, Auto-Align didn’t work for my images. So it was on to the hard method.

auto-align-layers

The hard way: manually aligning layers This method is more slow than hard. (Still harder than the easy way, though!) Change the opacity of the second layer, and visually align it to the bottom layer using the move tool. You can get the move tool by pressing “v”. I’ve circled it on the tool panel in the image below. On the layer panel, I’ve circled the opacity settings too. I set the blend mode to “Difference”, which makes the differences between the two layers the brightest. Then I visually lined up the center of the explosion, as I show in the first image below. The second image shows the same view before manual alignment.

If you have more than two layers, as I do in the full-sized image, work your way up from the bottom, and use the “Difference” blending mode to align each layer to the bottom layer. Remember to put all your blending modes back to “Normal”!

After manipulation:manual-align

Before manipulation:manual-align-begin

Step 3: Creating the composite

Now that your layers are aligned, it’s time to put them together! Woo! This is a two-step process. First, create a Smart Object from your layers, and then set the Smart Object Stack Mode to “Maximum.”

Creating a Smart Object Select all your layers. Then go to the Layer menu, go down to Smart Objects, and select “Convert to Smart Object.” (See the first image below.) A Smart Object is a kind of envelope Photoshop uses to perform certain tasks. They’re great! You can read more about them here. Here, we need to make a Smart Object so we can use the Smart Object Stack Modes. After you create the Smart Object, you will only see one layer, and it will have the page icon that I’ve circled in red in the second image below. If you ever want to interact with the layers again, say to change the alignment, you just double-click on the Smart Object. We’ll do just that in Step 4 of this tutorial.

Before making the Smart Object:make-smart-object

After making the Smart Object:smart-object

Setting the Smart Object Stack Mode Now you have a Smart Object! In Photoshop CC and in the extended versions of previous Photoshops, you have access to a number of Stack Modes. As in the first image below, go to the Layer menu, then Smart Object, the Stack Mode, then Maximum. (Later, you can play with other Stack Modes, but for now, choose Maximum.) The Maximum Stack Mode looks at each pixel of the image and selects the highest luminance value for that pixel amongst all the images in the stack.

stack-mode

When you use all 9 images that I provide (rather than 2, as above), you’ll get the image below. Which is pretty fun! Because each pixel is the brightest of all the 9 layers, we get a sort of stop motion slo-mo image. And we can make it even better!

 

stacked

Step 4: Refining the composite

I think the middle of the fireworks is too muddled in the image above. I can’t do anything to alter the Stack Mode logic, but I can change the layers that it makes its choices from. And that’s exactly what I’m going to do!

Double click on the Smart Object image to open the contents of the Smart Object in another tab. You can change the Blending Modes and Opacity (green circle), or you can reduce the opacity of certain parts of each image using Layer Masks. You can create a Layer Mask by clicking the icon in the yellow circle. The Layer Mask for one layer is shown in the red circle on the bottom right. Click it to select it, which allows you to paint into the Layer Mask. Where you paint in darker colors, the image will become more transparent. Learn more about Layer Masks here. You can also perform other layer adjustments, such as Levels or Exposure. I prefer to do such adjustments in Lightroom before I even go to Photoshop, but there are no wrong answers.

If you ever want to see the effects of your changes on the final product, simply save your changes to the content of the Smart Object, and go back to the tab that shows the Smart Object. in-smart-object

Resources

Click here to go to the Flickr folder of full-sized images, or use the smaller images below.

layer1 layer2 layer3 layer4 layer5 layer6 layer7 layer8 layer9

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Macro photography methods: early spring blooms

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Here in Virginia, spring is just beginning, and most of the signs of it are small and close to the ground. This spring, I decided to zoom in on that small world. Macro photography can be expensive, but it doesn’t have to be. For my photos, I used a 100 mm macro lens, some extension tubes to cut the minimum focal distance, and a kick light for illumination. If you don’t have a macro lens, you can also get great macro images using any lens with reverse lens macro. I used reverse lens macro to capture the image below.

Resistors with reverse macro

While I waited for a warm day, I practiced indoors. Below is an image of a civil war token lit with a kick light. Kick lights are great– they are small and bright, and you can couple them to your smart phone to control the color of the light. I chose blue here, thinking it might complement the copper tones of the coin.

Token the size of a penny. Lit using a kick light set to blue light.

Token the size of a penny. Lit using a kick light set to blue light.

In another exercise, I went to the kitchen and took pictures next to the window. This way I could think about natural light without dealing with the more trying aspects of nature like wind and the lack of convenient countertops.

A bottle cap in macro.

A bottle cap in macro.

Finally I got a nice day. My first subject was a lenten rose. Viewed from above, these early bloomers look more like shrubs than flowers. Only from below do you see what pretty flowers they are. Which means getting underneath a shrub-height flower.

I used a kick light to pull up the deep shadows in the middle of the flower. A gorilla pod (a simple $10 mini-tripod/flexible grip sort of thing) let me get the kick light where I needed it. After some trial and error (and some laying in the dirt and cursing the glare on my view screen while simultaneously really appreciating the view screen since my older camera doesn’t have one), I got this image below. With the aperture set to f11, the depth of field is good. A few of the stamen are out of focus, and I wonder if another stop or two would have captured them. I didn’t notice them while I was taking the image. Still, pretty pleased with this image.

A lenten rose in macro, lit from beneath with a kick light.

A lenten rose in macro, lit from beneath with a kick light.

Next I found some scilla. These flowers are electrically blue, but they are dinky. Each flower below is about the size of a penny. They were growing in deep shadow, so again I used the kick light, this time more to achieve the contrast and the white balance I wanted.

Scilla flowers in macro.

Scilla flowers in macro.

Later, I found some moss growing on a brick. For this image, I used my extension tubes. They cut the light, but they allow great and affordable zoom. This was in full sun, so I didn’t need the kick light. I find this image slightly creepy, like those tendrils are going to grow into the pine cone and consume it. Here the aperture is f4– this was for effect rather than for exposure.

Moss and pine cone on a brick in macro.

Moss and pine cone on a brick in macro.

And finally, my favorite image of the day, a lovely purple crocus. This shot was just a matter of playing with angles and trying to stay in focus. Happy spring, everyone!

Crocus in macro.

Crocus in macro.

Food and science: sous vide or water bath cooking

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In sous vide cooking, food is cooked in a water-bath at low temperatures (130-150 F) for longer times. Food cooked sous vide can be radically different in texture and taste than food cooked by more traditional methods. Even better, sous vide cooking is really, really easy.

What is sous vide?

In sous vide cooking, food in plastic bags is placed in a fixed-temperature water bath. The water bath temperature is held most easily by a digital controller. Some people build their own systems on the cheap. I bought this one, which in my opinion is worth every bit of $200.

As I discussed last week, bacteria die above 125 F. Consequently, food can be cooked at any temperature above 125 F (the closer to 125 F, the longer required for sanitation). This means a steak can be cooked to 130 F and be rare throughout, but also safe. For a 1 inch thick steak, this takes about an hour.

Why is it different?

Like a crock pot, sous vide cooking can be used to make tough cuts of meat extremely tender. Unlike a crock pot, the user has precise control over the set temperature, and the food is isolated from the water in which it cooks. This means that sous vide food isn’t soggy like slow cooker food so often is.

When we cook meat, the textural and color changes we observe are due to changes in the protein of the meat. Different proteins break down at different temperatures. The controller I use (linked above) allows control down to 0.1 C or 0.5 F. With such fine control, the cook can choose the exact temperature at which they wish to cook, and thus the effect they’d like to have on the protein. Poached eggs best demonstrate the results of this control. The proteins in the yolk coagulate at lower temperatures than the proteins in the white. By changing the cooking temperature only slightly, the cook can dramatically change the textures in the poached egg. This is called the perfect egg–at the link you can see eggs cooked to a variety of temperatures.

The set-up

For my set-up, the only major cost was the controller. I clamp it to the edge of a 8 qt pot (bigger would be better, but it’s what I had). Many people vacuum-seal their food before cooking, but the sealing system is an additional cost. I put my food in ziplock bags (glad bags are reported to be BPA-free). Then I add a little oil, squeeze the air out, and seal. To start cooking, I wait for the water in the pot to heat up and I clip the bag to the edge of the pot with a clothes pin.

Recipes and further reading

  • Citizen sous vide: an excellent general guide, with links to recipes and product reviews. Recipes are sorted by meat and cut.
  • Douglas Baldwin’s A Practical Guide to Sous Vide: a more technical discussion of sous vide with straightforward and instructive videos. This guide really explains the motivations of cooking sous vide.
  • Recipe for tri-tip steak: this recipe suggests cooking a tri-tip at 130 F for 6 hours, results shown below. You can see the meat is still pink in the middle. Cooking for six hours allowed it to tenderize, and all I had to do was cut up some meat and stick it in a bag. Very easy and delicious.

  • Tri-tip steak cooked sous vide.

    Tri-tip steak cooked sous vide.

Sports photography

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When I go to sporting events, I like to take pictures. Sports photography is really challenging, especially if you operate on a limited equipment budget and don’t get any kind of special access. I’ll list a few challenges I’ve encountered, and how I solved them. I shoot with a Sony α-850, but learned on a Sony α-100, so my experiences should translate to any basic SLR camera.

Challenge 1: The lighting isn’t strong enough

Whether you are indoors or the light of day is fading, this immensely effects the kind of photos you can take. My camera is susceptible to graininess at higher ISO numbers, which I hate. I set the ISO to the highest number I can stand, then I shoot in aperture priority mode in the smallest f-number (largest aperture) possible at the zoom required. I like to turn down the exposure by a couple of stops; it is easier to add brightness to an image than to remove blur. You may also need to add some saturation if you under-expose.

I used this procedure to take the picture of Michael Phelps swimming, below. Incidentally, this is the picture for breast stroke and swimming on wikipedia, and for swimming on Facebook. If you aren’t trying to make money off your photos, you can have some great fun seeing how they spread if you add them to the creative commons. (support the creative commons!)

 

SONY DSC

Challenge 2: The lighting is not white light

This can happen both outdoors with twilight or cloudy conditions, or indoors with certain types of lighting. The indoors case is a lot harder to deal with because it is harsher and more unnatural. There are a couple of different strategies– you can be proactive and take a reference picture of a white object during your shoot. You can change your white balance to match this reference during then shoot, or later in the post processing (I post process in Aperture), you can set the temperature/tint for all the photos to the combination that makes the reference shot a neutral color. If you change angle, the color of the light may change, so if you shoot from many angles this gets hard no matter your strategy. I always do my color changes in post-production. If you wish to, it’s important to shoot in raw (rather than jpg), otherwise you can degrade the image.

The pair of images below show a picture with and without temperature/tint correction. (I have also increased the brightness and saturation, but little else.) Note that the skin tone is more ashen in the first picture. I used the bonnet and the goal posts to hone in on a good neutral.

SONY DSC SONY DSC

 

Challenge 3: The focal plane changes rapidly and fast movement

When shooting sports, I always want to shoot with the largest aperture. This way, I can shoot at a lower ISO (i.e., less noise) and still have fast photos. Additionally, uninteresting stuff in the background gets blurred out by the focal depth. However, this shallow focal range ruins the picture if the objects of interest aren’t in that range. For some events, getting the objects in the focal plane is harder than capturing without motion blur, so I increase my aperture to the f5-f8 area.

Below is a picture I took at a horse race. Horse races are the best example of what I described above– the horses thunder towards you so quickly that in the time it takes for a cheaper SLR to focus, the distance of the horse has changed a lot. If the focal depth is shallow, the horse is likely not in it. But there is plenty of natural light, so I can increase the f-number without getting too slow.SONY DSC

Happy photoing! There are myriad other sports photo problems to solve, but I think I’ve been long-winded enough for today.