Photographing reflection Holograms

Getting a good photograph of a hologram isn’t always an easy proposition but if you use the right tools and are patient you can get excellent results just about every time.

This tutorial assumes you have full control of the hologram and can take it off the wall at will. If you’re trying to take a picture of a hologram that’s permanently mounted to a wall or one where the owner won’t allow you to move it, you’ll need to adjust accordingly.

Materials needed:

  • Hologram. Duh.
  • Digital camera, preferably with manual exposure, aperture metering controls.
  • Tripod. The heavier and more stable the better but use what you have.
  • Black cloth for a camera & operator cover.
  • Bright light source. Either a white halogen or a colored bulb or filter for narrow-band replay. This is optional but can help get you a clearer deeper picture.
  • Image editing software. Yep, I actually put that down. You’ll see why.
  • Light background if you have a dark frame, dark background if you have a light frame. This can be anything from cloth to cardboard. You just want a relatively evenly colored neutral background that contrasts with the frame around the hologram.
  • A dark room or room with very dim lighting.
  • Glass cleaner & cloth.
  • A table, chair, stool or some other surface to place the hologram on.

The first thing you should do is set up the room you’ll be working in. Make sure you’ve got plenty of room to work in and place your table in the center of your working area.

Place your background on your table so that it will fill the frame in your camera.

Set up your light so that it’s aimed down on the table from 45 degrees or so, you’ll have to adjust a bit depending on the replay angle for your hologram. Put the light as far away from the hologram as you can get it and still get a bright replay image. In the image below I’ve got the light on a tripod. The light is also screwed into an adjustable base so that I can make the light dimmer or brighter as needed.

 

Now set up your camera and tripod several feet away. You want the camera far enough back that you have to zoom all the way in for the hologram to fill the camera frame. This is so that the edges of the hologram frame will appear square in the final photo.

Cover the camera with the black cloth and poke the lens out through the hole in the cloth. The black cloth is used so that there won’t be any reflections of the camera or operator in the final image. Note that if your room is dark enough, you may not have this problem and will not need the cloth. You’ll just have to see how things go for you.

I just use a rubber band to hold the cloth securely around the lens. This prevents the cloth from shifting and covering up the lens as you’re working.

Take your glass cleaner and clean the glass and frame. There’s no point in having dust or fingerprints in the final image, so here’s your chance to make it perfect. If you can, go so far as to remove the glass from the frame. You can always put it back later.

 

Place the hologram on your table and center it within the background.

Align the light so the hologram shows up nice and bright from several feet away. Now take your camera and with maximum zoom (remember to turn off digital zoom if your camera has it) figure out where the camera needs to be get the best picture.

Place your tripod at that point, put your camera on the tripod and get things aligned again. You want the hologram to fill the frame as much as possible.

Now you’ll have to play artist and play a bit. Remember that you’re using a digital camera and take lots of shots but at the same time keep a record of your settings. If your camera records all the settings as part of the exif data you can rely on that rather than writing the settings down.

Take several pictures while modifying the f-stop, aperture, metering and any exposure bias controls available to you. You want the best compromise between exposure and brightness of the image.

For example, in the P-51 image I had to dim down the image in the camera to keep the plane from being blown out. I could also have done this as a post-processing step but I’ve found that I get the best results by making the changes in the camera.

After you’ve taken your pictures, download them to your computer and pick the best one.

Once you’ve done this you might be tempted to upload the image to the net and be done with it but you probably are really done yet.

Take a very close look at the image, looking for dead pixels and dust.

The camera that I’ve found takes the best pictures of holograms also has a few dead pixels.

Take the image into your favorite editor, I use Gimp, and use the smear or clone tool to blend the pixel into the rest of the image.

You’re done!

 

 

Author: Michael Harrison

Husband, Programmer, Irish dancer, tinkerer, astronomer, layabout (as much as possible)

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