Posts Tagged ‘how to’

Dragonflies in Flight

February 20, 2013

Dragonflies in Flight” is a slideshow featuring 68 still photographs by Walter Sanford. (Hey, that’s me!) The soundtrack is the song “Fly Away” by Lenny Kravitz (3:41 min).

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Tech Tips: The still photographs were adjusted using Apple Aperture and exported as 16-bit TIFFs. The TIFFs were imported into Adobe Photoshop Lightroom 4 as a collection. The “Slideshow” module in Lightroom was used to create and export the slideshow (56 MB). Watch Adobe TV and learn how to use Lightroom 4 to create a slideshow with music: “Publish a Slideshow,” by Julieanne Kost. See also, Stop-action photography of dragonflies in flight.

Copyright © 2013 Walter Sanford. All rights reserved. www.wsanford.com

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Stop-action photography of dragonflies in flight

January 27, 2013

It is estimated a dragonfly flaps its wings at about 30 beats per second. I shot several photos of a dragonfly in flight using a shutter speed of 1/1,300 second. Turns out that shutter speed was a little too slow to stop wing motion completely.

I posed the following question to Phil Wherry, my good friend and technology/photography guru: How fast would the camera shutter speed need to be in order to freeze all motion of a dragonfly in flight? Phil’s answer is as follows.

To freeze all motion? Infinitely fast. Even if your exposure is one-millionth of a second long, the wings are going to move a little bit during that interval.

You’re going to get some motion no matter what; the question is simply how much is tolerable. At some point the motion will be small enough that the image will look sharp to you. (This same principle, by the way, applies to depth of field: Focus is only perfect at a single plane no matter what the aperture, but the “depth of field” defines the area where the error is small enough that it’s not obvious.)

We’ll start by considering a simpler scenario. Let’s say you have a motor that makes one full rotation per second. Let’s also say you take a paper plate and draw a thick black line on it, then attach that to the motor shaft. Now you have something that looks a bit like a one-handed clock, with the “hand” making one full rotation every second.

Now, let’s say you point your camera at this setup. If you take a one-second exposure, the “hand” will rotate once during the exposure; clearly you’ll have a lot of motion blur. If you shoot at 1/4 second, the “hand” will traverse just one-quarter of the circle. Shoot at 1/100th of a second, and you’ll get a little bit of motion blur as the “hand” swings through 1/100th of a circle. If you shoot at 1/1,000th of a second, there’s still some motion blur but it’s probably not enough to make you perceive the result as blurry.

Now let’s consider the motion of the dragonfly’s wings in detail: If the wings are beating 30 times per second, that means the wing goes through one complete cycle of its motion 30 times per second. Let’s say for a moment that you shoot a picture at 1/300th of a second. This is ten times as fast as the wings are beating, so you’ll capture 10% of the range of motion. At 1/1,300th second, you’re capturing 30 / 1,300 (or about 2.3%) of the wing’s beat cycle.

This is made more complicated because the wings aren’t moving at a uniform speed; they accelerate and then slow down, reverse direction, accelerate, etc. The result is, as one might expect, roughly sinusoidal in shape (though not exactly; see the blue line in Fig. 2 of “Dragonfly Flight“).

If that 1/1,300th of a second exposure happens to occur when the wings are at the end of their travel and beginning to reverse direction, very little motion will occur and the image will look sharp. If the wings are mid-stroke, then some 1/1,300th of a second is likely to have some motion blur.

Experimentation is really the only way you’ll figure this out. Flash might help, too, since a major contributor to the overall exposure would then be a pulse of light that’s only a fraction of a millisecond long.

Phil

The following photos illustrate the relationship between shutter speed and stop-action photography of dragonflies in flight: Photo 1 of 2 was shot using an aperture of f/5.2 and a shutter speed of 1/200 second; Photo 2 was shot at an aperture of f/3.8 and a shutter speed of 1,300 second.

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Copyright © 2013 Walter Sanford. All rights reserved. www.wsanford.com

Advanced technique for creating Diptic "photo tiles"

December 27, 2011

I like to use Apple Aperture to prepare ready-made “photo tiles” that are the perfect size to add to the panels in a Diptic layout. That said, some photos can’t be cropped to a size of say 1024 x 1024 pixels square without losing critical parts of the photo. Here’s a solution that is both simple and elegant — it’s called “round-tripping.”

I set Aperture’s “Export” preferences to hand-off a copy of an image file to an extrnal photo editor. I’m using Adobe Photoshop, but a much less expensive application such as ImageWell works too. I selected an image in my Aperture Library (see Photo 1 of 3, below), chose the Crop tool and “Square” Aspect Ratio, and selected an area that is 1723 x 1723 pixels square (see Photo 2 of 3, below). From the Aperture menu bar, I selected Photos > Edit with Adobe Photoshop…; Photoshop opened and I changed the image size to 1024 x 1024 pixels square. From the Photoshop menu bar, I selected File > Save; voila, the re-sized image appeared in my Aperture Library (round-trip completed)! Finally, I exported the re-sized photo from Aperture as usual (see Photo 3 of 3, below). Now the photo tile is ready for use in a Diptic diptych. Simple, huh? Really, it’s simpler than it sounds and best of all, there’s none of the loss in image quality that would occur by opening/editing/saving a photo in two-or-more applications. Now that’s cool!

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Tech Tips: When cropping a selected area from a photo that will be re-sized, be sure the dimensions of the selected area are larger than the intended dimensions of the re-sized version. Otherwise you may see “jaggies” in the final image.

Photos © Copyright 2011 Walter Sanford. All rights reserved. www.wsanford.com

Another diptych of dragonflies

November 29, 2011

The following composite image, known as a diptych, was created using Diptic app for Apple iOS mobile devices. The diptych shows Great Blue Skimmer dragonflies (Libellula vibrans) spotted during photowalks through Huntley Meadows Park, Fairfax County, Virginia USA.

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In order to create a “Hi-Res” Diptic (resolution = 2048 x 2048 pixels) like the one shown above, I used Apple Aperture to crop photo tiles from the source images in the following sizes: 1024 x 1024 pixels (square); 1024 H x 2048 W pixels. Next, I used iTunes to sync the photo tiles to my iPad. Finally, I launched Diptic, selected the photo tiles, and added black and white borders with a width of 10 pixels.

The following workflow was used to crop the photo tiles in Aperture:

  1. Choose a photo to edit. From the menu bar, select Photos/Duplicate Version.
  2. Select the new version of the photo.
  3. Select “Crop Tool” and drag a selection area on the image — don’t worry about the size of the area. Note that the “Master Aspect Ratio” of the Master Version is shown in the Crop Tool HUD; do not change the aspect ratio. (Under unusual circumstances, you may need to select “Do Not Constrain.”)
  4. Under the “Adjustments” tab, select “Crop.”
  5. Enter values for the new height and width, in pixels.
  6. Click-and-drag the crop selection box to desired position.
  7. From the menu bar, select File/Export/Version…; save file to desired location.

Photo © Copyright 2011 Walter Sanford. All rights reserved. www.wsanford.com

Comma butterfly

July 2, 2011

Small Cabbage White Butterfly on Cabbage Plants

June 10, 2011

On 10 June 2011, I photographed a cluster of 43 Small Cabbage White butterfly eggs on the underside of a cabbage plant leaf. (Yes, I counted them.) In the following gallery, Photo 1 of 2 is a copy of the original photograph, annotated to highlight the egg cluster; Photo 2 of 2 is the original photograph. Apple Preview was used to annotate the photo.

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Better Geotagging, revisited

May 2, 2011

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In a recent blog post, I shared a simple tech tip for better geotags in iPhone photographs: Launch the Maps app and verify your location BEFORE taking pictures with the Camera app. I should follow my advice! Huh? Look at the Flickr Map (shown above) of my photo gallery, “April showers bring May flowers.” All of the photos in the gallery should be located on three streets in Hollin Hills (listed in chronological order along my photowalk): Elba Road; Nordok Place; and Mason Hill Drive. As you can see by looking at the map, there are several outliers that are not located (geotagged) correctly. Question is, what caused the photos to be geotagged incorrectly?

Apple iPhone is the best all-in-one device for geotagging photographs, as I explained in “The ABCs of A-GPS.” iPhone “Location Services,” as good as it is, can be surprisingly inaccurate after an iPhone has been either in sleep mode or powered-off. It was raining lightly during most of my photowalk through Hollin Hills on Sunday: When I stopped to take photos, I was in a rush to prevent water damage to my iPhone and did not use the Maps app to verify my location before shooting pictures; my iPhone was in sleep mode between stops along the photowalk. Net results: My iPhone wasn’t damaged (that’s good news); several photos were geotagged incorrectly (that’s bad news). Perhaps I could have avoided the problem by running a GPS-tracking app in the background, such as MotionX GPS. Point is, you can’t assume an iPhone will correctly geolocate every photograph you take with its built-in camera, but you can get better results by using the Maps app to get an accurate position fix before taking photos.

Finally, a quick word about the Flickr photo sharing service. Is it just me, or is the Flickr user interface often less than intuitive? I was sure I set up my Flickr account to enable sharing photo location information. Turns out I was wrong. I discovered the solution after troubleshooting the problem. Sign in to Flickr. Click on the hyperlink labeled, “Your account.” See the section entitled, “Defaults for new uploads”; for the setting, “Import EXIF location data,” select “Yes.”

iPhone Photography Tech Tips: Better Geotagging

April 18, 2011

Here’s a simple tech tip for better geotags in your iPhone photographs: Launch the Maps app and verify your location BEFORE taking pictures with the Camera app. You’d be surprised how inaccurate “Location Services” can be after an iPhone has been either in sleep mode or powered-off.

Combined GPS Track & Photo Gallery for Display in Google Earth

March 11, 2011

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As promised in my last post, Photowalking Hollin Hills, here are step-by-step instructions describing the workflow for creating a KMZ file that features a GPS track and gallery of geotagged photos, suitable for display in Google Earth.

  1. Save- and export a track (GPX file) from a GPS device, such as MotionX GPS for Apple iPhone.
  2. Create a gallery of geotagged photos using Picasa for Windows.
  3. From the menu bar in Picasa, select Tools/Geotag/Export to Google Earth File; save the resulting KMZ file to a known location. (Editor’s Note: This option is not available in Picasa 3.8.7.361 for Mac OS X.)
  4. Open the KMZ file of geotagged photos in Google Earth.
  5. Open the GPX file (GPS track) in Google Earth; drag the GPX file into the KMZ folder of geotagged photos.
  6. Select the KMZ folder (containing both the GPX track and geotagged photos). From the menu bar in Google Earth, select Save/Save Place As…; create a name for the new KMZ file and save to a known location.

A sample KMZ file (Picasa_23Feb2011.kmz) is shown above.


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