Ever seen those images with several images of the moon and wanted to replicate it but in a single shot? You can take a few shots and create a composite shot in Photoshop. But can it be done in a single shot without a lot of fancy/expensive equipment? I thought it would be an interesting challenge to try. So, here's an instructable on how I got the shot.

Theory

The basic theory behind the shot is simple: leave the camera shutter open for a long time but block the lens most of the time. So, what we need is something that blocks out the light, is easy to open and close, and introduces a little vibration as possible. Once the light blocker is in place, we start the shot and open the light blocker at regular intervals.

This instructable consists of two distinct sections. The first section deals with creating the light blocker. The second deals with taking the shot.

Equipment

Here's a list of what you'll need:

- filter holder compatible with Cokin P Series filters
- Square filters lens hood for Cokin P Series holder
- Adapter ring (one for each lens you want to use it with
- Black nylon cloth (minimum size 16"x16" or 8"x32"; recommended size 20"x20" or 10"x40")
- 2 Magnets
- Square food container (bottom should be about 5"x5"), no lid necessary
- Plasti Dip spray
- Glue gun and several glue sticks
- Wax paper
- Old newspaper, a drop cloth, or something to protect your floors
- Scissors

- DSLR camera with full manual control
- Camera remote control or Remote Shutter Release Cable
- Tripod
- extra camera battery (optional but highly recommended)

Equipment Notes
- For filter holders, there's also an "A" Series but there doesn't seem to be a hood for it.
- The minimum cloth size requires some precision when gluing the cloth to the filter holder. The recommended size will be easier to glue (you don't need to be as precise) and will require additional trimming.
- I used nylon cloth because it's strong and lightweight. Nylon is also less absorbent than some other cloth types, which is a bonus in this case.
- Use medium strength magnets - avoid the neodymium magnets. The magnets should be strong enough hold a bit of weight but weak enough that they pull apart easily. If they're too strong, you'll introduce too much vibration and may actually pull the camera out of position.
- The Plasti Dip spray will be used to make help block out the light and cut reflection. The spray version is easier to apply than the dip version so try to get that. (Check the Plasti Dip site http://www.plastidip.com/diy_where_to_buy.php for where you can find the spray.)
- Use as sturdy/heavy a tripod as possible. This will reduce the chances of the camera moving out of position.

Additional Note
In theory, you may be able to do this by keeping the lens cap on for most of the shot. The main problem with relying on the lens cap comes when removing and reattaching the lens cap. Taking the lens cap off will cause the camera to shake, which may cause a blurry shot and/or the camera moving out of position. If you pause with the lens cap in front of lens after taking it off (to let the camera stop moving), a lot of light may come in from the sides or reflect off the lens cap interior and ruin the shot.

Step 1: Preparing the Cloth and Container

In the first step, we'll prepare the cloth and the food container. We need to make the container bottom and the nylon cloth opaque. Nylon cloth will let moderate to strong lights through - just hold some up to a light to see for yourself. We want both as opaque as possible to protect against flashlight beams, car headlights, and other light sources.

For this step, we'll need the following:
- Black nylon cloth
- Square food container
- Plasti Dip spray
- Wax paper
- Old newspaper, a drop cloth, or something to protect your floors

Pick a well ventilated area to work in, as the fumes from the Plasti Dip are harmful. Lay down the newspaper to protect the floor. Next, lay out sheets of the wax paper. The cloth and food container will sit on the wax paper rather than directly on the newspaper. The wax paper is less likely to stick. Put the food container on the wax paper, open side up. Spray the interior bottom with the Plasti Dip. Don't worry that you can still see through it. You'll need several coats. Once sprayed, flip the container over. Prop up at least one side of the container so that air can flow to the inside of the container. Spray the outside bottom of the container. Set aside to let dry. Once dry, repeat the spraying one or two more times.

While the container is drying, work on the cloth. If desired, fold the cloth in half (so the area is 8"x16" if using the minimum size) and iron the edge. This is to make it easier to fold. Put the cloth (unfolded on top of the wax paper. Spray one half generously with the Plasti Dip. Fold the other half on top of the sprayed portion. Place a layer of wax paper on top and press down to ensure there are no air bubbles. Place a weight on the folded edge (I used the wax paper dispenser). Let dry. After at least 15 minutes, remove the weight from the folded edge. Also remove the top layer of wax paper. This is to increase air flow and help the cloth dry. Wait until dry.

The instructions on the can say it takes 30 minutes to dry. For the cloth and the final coat for the food container, it's best to wait longer, possibly even a couple hours, just to make sure it's completely dry.

Step 2: Preparing the Filter Holder

Do this after the cloth has dried. It's not necessary for the container to be finished at this point. For this step, we'll need the following:
- The prepared cloth
- filter holder
- Glue gun (and glue sticks)

Cut the cloth in half so you have 2 pieces that are at least 8"x8". Set one piece aside. Place the filter holder as shown in the first photo. Apply glue generously to the inside of the filter (both the ring portion and the sides. Press the cloth into the filter, making sure the filter is in the center of the cloth. The cloth should come up over the sides and extend out at least an inch on each end. Wait for the glue to cool and set.

Note: The cloth size shown in the photos is a lot larger than 8"x8" (probably closer to 11"x11").

Step 3: Attaching the Lens Hood

Now we need to attach the lens hood to the filter holder.

For this step, we'll need the following:
- The filter holder with cloth
- Square filters lens hood for Cokin P Series holder
- Glue gun (and glue sticks)
- Scissors

Attach the lens hood to the filter holder. Make sure filter holder is as far into the lens hood as possible. Also make sure all the cloth is on the inside of the lens hood. Pull back the cloth on one side and apply glue to the inside of the lens hood. Press the cloth to the side with glue. Repeat for the other three sides.
When the glue has set, cut off the excess cloth. The corners at this point are probably still loose. Glue the loose cloth at the corners down. It doesn't have to look pretty, it just needs to be out of the way. Again, wait for the glue to cool and set.
Once the glue has set, cut out the center of the cloth. The hole you cut should be as close as possible to the opening for the lens but it doesn't need to be fully cut out. Enough cloth needs to be cut away so the lens, when attached, is not obstructed.

Step 4: Modifying the Food Container

Now it's time to start working on the flap. The first thing we need to do is to cut out the bottom of the food container and attach it to the cloth previously set aside.

For this step, we'll need the following:
- The food container
- The prepared filter holder
- The remaining cloth piece
- Glue gun (and glue sticks)
- Scissors

Make sure the bottom of the container is opaque and well covered by the Plasti Dip. If it isn't, add another coat and wait until it is dry. Once the container is ready, cut out the bottom, making sure it's larger than the lens hood. Once the bottom has been cut out, use the lens hood as a guide and cut out a square in the shape of the lens hood. Now, take the cloth that was set aside. Apply glue to the center of the cloth or the container bottom and glue the container bottom to the center of the cloth.

Step 5: Attaching the Flap

We now need to attach the flap to the lens hood.

For this step, we'll need the following:
- The prepared filter holder
- The cloth with the container bottom
- 1 magnet
- Glue gun (and glue sticks)
- Scissors

Determine which side of of the lens hood assembly is the top. Apply a dab of glue to the top of the lens hood. Press a magnet into the glue and wait for the glue to set. Lay down the cloth with the attached container bottom, making sure the side with the container bottom is facing up. Place the lens hood on top of the container bottom, lining it up. Make sure the open square end of the lens hood/filter holder combo is the side touching the cloth. Determine which side of the filter holder is the bottom. Apply glue on the outside of the lens hood on the bottom side and attach the cloth. This side will essentially serve as the hinge. Once the glue is set, trim the cloth, leaving at least an inch on the unglued sides.

Step 6: Finishing the Flap

Now it's time to finish up the flap.

For this step, we'll need the following:
- Filter holder and flap assembly
- 1 magnet
- Glue gun and glue stick(s)
- Plasti Dip spray
- Old newspaper, a drop cloth, or something to protect your floors

Apply a bit of glue to each corner of the cloth and pinch each corner to form a bowl-like shape. When the glue is dry, snip off the glued portions of the bottom corners. The flap is now almost complete.
Test the flap to make sure it swings easily. If it doesn't, chances are, there's excess glue at the bottom. Using the scissors or a knife, cut or scrape off as much glue where the cloth of the flap is connected to the lens hood, taking care not to cut into the cloth. Repeat until the flap swings easily.
Now, take the second magnet and determine which side of the magnet will properly connect to the already glued magnet. Place a bit of glue on that side of the magnet. Pull the cloth of the flap top over the magnet attached to the lens hood, making sure the flap is closed relatively tightly. Place the glued side of the magnet onto the flap cloth, lining it up with the magnet on the lens hood. Wait for the glue to set, leaving the magnets connected.

Step 7: Completing the Light Blocker

The light blocker is essentially complete but we'll do one finishing touch.

For this step, we'll need the following:
- The light blocker
- Plasti Dip spray
- Wax paper
- Old newspaper, a drop cloth, or something to protect your floors

Now it's time for a final spray of the Plasti Dip. If you're like me, there's some glue visible at the edges of the plastic container bottom. Remove as much of the excess glue as you can. You don't have to be too meticulous about this so don't spend a lot of time and effort on glue removal. Open up the flap and place the light blocker on the wax paper and newspaper. The inside of the flap (with the container bottom) and the inside of the lens hood should be visible. Spray the flap interior and the lens hood interior with the Plasti Dip. This will coat any visible glue as well as lightly coating the cloth. The reason for this final spray is two-fold. The glue remnants will reflect light, given its light coloration. The final spray will coat the glue and cut the light reflecting off the glue remnants. Nylon is naturally slightly shiny and the final coat of Plasti Dip should cut some of this reflection as well. Wait for the final coat to dry.

The light blocker is now complete. All that's left is to actually take the shot.

Step 8: Testing the Camera's Limits

Before rushing out to take the shot, there are test to run with your camera. For digital cameras, if the power fails during a shot or while the camera is processing a shot, the photo will be lost. So, it's important that the camera battery does not fail during the shot. At the same time, you'll want to leave the shutter open for as long as possible to get the most number of moon images as possible. You need to find out how far your camera can be pushed.

For this step, you'll need the following:
- DSLR camera

There are two things you need to find out about your camera. The first is how your camera processes shots when taking photos in bulb mode. If you still have it, consult the user manual. If you no longer have the manual, you'll need to run a test. Switch the camera to manual mode and set the shutter speed to bulb mode (keep increasing the time until it switches to bulb mode - for the Sony A330, it does this after passing 30 seconds). Use the remote control or remote shutter release cable to take a photo that leaves the shutter open for a couple minutes. You can leave the lens cap on - the photo doesn't matter, just the timing. End the shot and determine how long the camera spends processing the photo. For the Sony A330 (the camera I have), it's a 1:1 ratio - if the shutter is left open for 2 minutes, the processing time is 2 minutes.

Now it's time to figure out how long your battery will last. Make sure the battery is charged up to full. Note the time, then, use the remote control or cable to start a shot and leave the shutter open. Chances are, when the shot is being taken, there may be no way to tell if the camera is still running. Make sure your camera display is on. If you're not sure of how long your battery will last, leave the shutter open for about an hour and a half. Otherwise, use the shutter:processing time ratio to determine how long the shutter can be left open. For the Sony A330, the ratio is 1:1 and the battery life is approximately 2 hours so the time the shutter can remain open is roughly an hour. Once the appropriate time has elapsed, use the remote control or remote cable to end the shot. If the display was not disabled, a message indicating processing is occurring may appear. Check the camera every few minutes to determine whether or not the battery has been fully drained or if the photo has finished processing. Note when the processing finishes or the battery dies. Using the shutter:processing ratio, calculate how long the shutter can be left open. For example, if the shutter for the A330 is left open for 1h 30m, and the battery fails after 20 minutes of processing, the shutter can be left open for roughly 55 minutes (total time = 90 minutes shutter open + 20 minutes processing = 110 minutes; with a ratio of 1:1, that means 55 minutes shutter:55 minutes processing).

You may want to charge up the battery and do an additional test, now that you have an idea of how much time you can leave the shutter open. Note that lithium-ion batteries don't perform as well in cold conditions so you may have to reduce your time estimates to account for the temperature during the photo shoot.

Step 9: Determining When and Where to Shoot

Once the camera limits are known, it's time to figure out when and where to take the shot. These instructions assume that you're going to be taking a shot of the moon setting.

First check when the sun and moon set. You'll want to choose a time when the moon sets at least 2 hours after sunset (and at least 2 hours before sun rise). You can google "moonset" or check this site: http://www.timeanddate.com/worldclock/moonrise.html. Make sure the moon isn't a new moon. Pick a date that meets these conditions. As that date approaches, check the weather reports. The ideal weather is a completely clear sky - no clouds at all. Clouds can obscure the moon and/or reflect enough light to mess up your shot. (The light reflection is generally only a concern if there's a lot of low cloud, like rain clouds.) You'll want a dark place away from the city lights, the darker the better. If all these conditions are met, grab your camera, tripod, and light blocker and head over to your chosen location on the appropriate date. Aim to arrive at least 2 hours before moon set so you can do some test shots. Take along an extra battery if you have one. This way, you don't have to worry about draining the battery while doing test shots.

If you're taking a different type of shot, the general advice still applies. Check the weather conditions and ambient light (e.g. light from street lamps, the moon, etc.). Make sure there's nothing at the site that would interfere (e.g. a highway in the background that may have car headlights shining directly into the camera). Arrive early to take some test shots to allow for test shots.

Step 10: On-site Preparation Part 1 - Checking Moon Speed

Head on out to your chosen location with your camera, tripod, and the light blocker. You may want to bring along an mp3 player and/or other things that will keep you somewhat occupied (but not so much that you're preoccupied) when waiting between shots.

Once you've arrived at where you want to shoot, it's time for phase 1 of the preparation. You need to determine how large the image of the moon should be in your shots and how many moon images you want. Keep in mind that the more moon images there are, the higher the risk for the shot.

First, point the camera towards the moon and check if the size of the moon in the viewfinder is what you want. If not, switch lenses or zoom in/out.

When you've determined how large you want the image of the moon, figure out how many images of the moon you want in the photo.

Once that's figured out, mount the camera on the tripod. Then attach the adapter ring to the end of the lens. Slide the light blocker onto the adapter ring. Make sure the light blocker is closed. Set the camera to manual control. Set the shutter speed to bulb and the aperture to the highest F number your lens allows. Set the focus method to manual (this is probably a switch on the camera body and/or the lens). Turn the focus ring so the camera is focused at infinity.

What needs to be determined now is the amount of time between moon images. Use the remote control/cable to start the shot. Open up the lens blocker briefly, then close it again. Note that for this test, neither reducing the vibration nor having the moon in sharp focus are necessary - we're just interested in the distance between the moon images. Wait a few minutes. Open up the lens blocker briefly and close it. Use the remote control/cable to end the shot. Wait for the processing to finish. Check the distance between the moon images. Adjust the time you wait before opening the light blocker. Perform this test until you are satisfied with the distance between the moon images.

Step 11: On-site Preparation Part 2 - Practice

Now the second and more difficult part of the preparation: practicing using the light blocker. The practice will consist of taking single shots of the moon using the light blocker. The goal is to get good enough using it that you open and close it at the appropriate "shutter speed" and without any blurriness in the image.

First, we need to determine how long you should leave the light blocker open. Point the camera at the moon. Adjust the aperture to its highest F-number. Set the shutter speed to 0.5 seconds. If you have a "Steady Shot" or other noise reduction setting, turn it off. Long exposure shots on a tripod should be done with this setting off. Take a photo of the moon and check the image. If the moon is too bright, reduce the shutter speed. If it's too dark, increase the shutter speed. Once you have a good image of the moon, look at the shutter speed. That's roughly how long the light blocker should remain open during each image.

Next is practice with the light blocker. Close the light blocker. Then use the remote control or cable to start the shot. Grab the top of the light blocker flap with your forefinger and thumb (I grab on either side of the magnet) pull the flap magnet up off the holder magnet. Move the flap forward slightly making sure the flap is resting on your remaining fingers. Pause for about a second to let any vibrations caused by opening the light blocker to subside. Let go of the top of the flap (held by your thumb and forefinger), making sure the flap is still resting on your remaining fingers. Move your hands down quickly so the flap swings down and exposes the lens. Make sure you don't move your hands too fast (the flap should be resting on your fingers at all times). If the flap loses contact with your fingers, there'll be a bit of a jolt when you stop your hands and the flap catches up and hits your fingers. After the lens is fully exposed, pause if necessary (if the "shutter speed" you need is roughly 0.5 seconds, no pause is necessary).

Bring your hands back up quickly, stopping when the flap is almost closed. We stop just before closing it so we don't accidentally jostle the lens (and risk pushing the camera out of position). Then carefully close the flap the rest of the way and secure it with the magnet. Take your hands off the light blocker. Once the flap is closed, use the remote control or cable to end the shot.

Here's a short video of the way I open and close the light blocker.

It's done more slowly than normal so I can provide the commentary but that's essentially how I opened and closed the light blocker each time. (I move my hands well away at the end to avoid jostling the camera. In the past, during other long exposure shots, I sometimes turned and my hand would smack the side of the camera hard enough to move the tripod out of position.)
If you're having trouble hearing what I'm saying, here's the very brief transcript:
"Unhook the magnet."
"Pause."
"Wait for the vibrations to stop."
"Down, up."
"Magnet back on."
"Wait for your next shot."

Wait for the camera to finish processing the shot. Check the image. If the image is too bright, the flap needs to be opened and closed more quickly. If the image is too dark, add a pause between the opening motion and closing motion. If the image is blurry, pause a bit longer after letting go of the top flap (after pulling the magnets apart). Also make sure you're not pulling on the flap. Also make sure the tripod isn't being jostled or that environmental factors (e.g. wind) aren't interfering. If the tripod is a bit wobbly, shorten the legs of the tripod, extending it as little as possible. The more you extend the tripod (both the legs and the central shaft), the less stable it becomes.

Practice until you can consistently get a good shot of the moon. Once that's accomplished, you're ready for the final shot.

Note that the more practice shots you take, the more your battery is drained. This will reduce the amount of time you have for the final shot unless you have a spare battery. It is for this reason a second battery is highly recommended.

Step 12: Taking the Shot

Now that the camera is set up and you've practiced with the light blocker, it's time for the final shot. Depending on how long you took practicing and the particulars of the shot, you may have to wait a while before you start the shot. For example, I calculated that I wanted 10 moon images, with the final image that of the setting moon. It was 5 minutes between shots, giving a total time of 45 minutes. So, I had to start my shot 45 minutes before the moon set.

Just before the starting the shot, swap out the battery (if you brought a second battery). Do a final check on your camera settings. Turn the camera's lcd display off if you can (to further extend battery life). Open the light blocker and adjust the camera position such that the moon is in its desired starting location. Close the light blocker and start the shot with the remote control or cable. Very soon after starting the shot, open and close the light blocker as you practiced. Wait the desired length of time and open and close the light blocker again. Repeat until you've captured the last moon image. At this point, you may want to wait until the moon fully sets, then open the light blocker for a few seconds to get a better shot of the landscape. This does carry some risks, as it may brighten the sky area enough to over expose the moon. With the light blocker closed, use the remote control or cable to end the shot.

Now the nerve-wracking part of waiting for the shot to finish processing. If you're done shooting, you can start to pack things up while the camera is processing the image.

For reference, the moon shot I took was at 105 mm focal length on an APS-C sensor (approximately 157 mm on a full frame camera or traditional 35 mm film camera). Aperture setting was F-32. ISO was set to 100. Total exposure time was 2717 seconds (45 min 17 sec). Lens blocker was opened each time for about 0.5 seconds. I did a test shot at the beginning in full manual with the shutter speed at 0.5 seconds and the moon brightness was comparable to the first moon image (upper left).

Step 13: Reflections and Ideas

Limitations

The light blocker currently has some important limitations. The main three limitations are related to vibration, timing, and lighting. Being attached directly to the lens, any vibrations from from opening and closing the flap are transferred directly to the camera. Ideally, the flap would be separated from the lens by something that would reduce or eliminate the vibration.
The second issue is the timing. The length of time the lens is exposed is entirely dependent on how precise you are in opening and closing the flap. As a result, if you're aiming for 0.5 seconds, being off by 0.25 seconds can be disastrous. Longer times are much preferred. If you're off by 0.5 seconds when exposing the lens for 5 seconds, it isn't such a big deal and may not even be noticeable. For bright objects like the moon, the times tend to be small and therefore timing is more crucial.
The third issue is lighting, or more specifically, general lighting. With the pause to let the vibration settle and the pause before reattaching the magnet, there's a chance that light from the surroundings can sneak in. With the flaps to the side and top, the light coming in from the sides are minimized. Strong light coming in from the rear is probably the biggest worry (which can be reduced by using your body or other objects). Even so, this light blocker works best in dark surroundings.

Original idea

My original idea for the light blocker was much more complex and would have addressed the issue of vibration. My original concept was to replace the flap with a system of two containers, one with the bottom cut out, the other acting as the flap. These containers would be attached to the lens hood by more cloth (so any vibrations would be absorbed by the cloth). The containers would be mounted on a second tripod in front of the camera. The main reason this fell through was the opening needed to be very close to the front of the lens or the container would start obstructing the shot.

Future improvements

To fix the timing and lighting issues, an automated system that replaces the flap would need to be created. Electronic timing would result in consistency with the timing. Potentially, a large electronically controlled shutter would do the trick. Mechanically, I don't know if a shutter of the required size would even be feasible. Of course, the more complex the system, the more it will cost.

Other types of shots

I chose a moon shot for this instructable because it's a shot I've been wanting to do for a while and a moon shot is done easily with just one person. There are numerous other shots that are possible. Armed only with a flashlight, an extra tripod, and paracord (or tape), you can do a shot where multiple objects are lit but the background and surrounding objects are still dark. For example, you could do the following:
- go to a garden at night
- point the camera at a bed of flowers
- set up the flashlight (tight beam) to light a single flower or small patch of flowers
- start the shot and open the light blocker briefly
- with the light blocker closed, move the flashlight to shine on a different flower
- open the light blocker again

If you add a second person, you can do some great Halloween themed shots. One person can operate the light blocker, the other can participate in the shot. You may want to try the following:
- go to a spooky location
- stand so that you will appear on one side of the photo
- make sure you're moderately well lit
- strike a pose
- have your helper open the light light blocker briefly
- move so that you will appear on the other side of the photo
- strike a pose
- have your helper open the light light blocker briefly
- move out the of the shot
- light up the background and open up the light blocker briefly (or leave it open longer if not using additional lighting)
This should, if all goes well, give you a single shot in which two ghostly images of you are present.

There are a lot of other shots you can experiment with (e.g. start walking and have your helper open the light blocker every second or two without fully closing it to save time).