Home

Links:

May, 2013 Flowers

July, 2010 Flowers

April, 2009 Flowers


Cowboy Studio


Helicon Focus

Zerene Stacker


Depth of Field Calculator


Focus Stacking

Introduction

In this session we started off reviewing the late "Best of 2013" images from Glenn Manuel, Priscilla Lonsford, and Raj Lokiah. These photographers have a lot of talant.

Ed Auger then led off with a presentation on Flower Photography. Ed's presentation is found here.

The balance of the evening was spent techniques to add fill flash and extend the apparent depth of field using focus stacking techniques.

The challenge with any type of photography is to use the tools we have available to create the desired image. Some of the tools we have available are various flashes, lights, and reflectors to fill in shadows and dark areas. We have other tools and techniques to render sharp object while blurring the background or to make the entire scene tack sharp. These are the tools we examined in this session.

 

This session covered:

  • Fill light using reflectors
  • Fill Light using off camera flash
  • Macro Focus stacking using a Rail
  • Macro Focus Stacking W/O a tripod
  • Focus Stacking using Helicon Remote

    • Macro
    • Landscape

Links to various Cowboy Studio products is shown to the right. The links are provided as examples and is not as an endorsement. I have used many of their products. As with any third party product, most are good and some are not so good.

1. Fill Light using Reflectors

No example pictures could be found.

A reflector can be used to:

  • Block direct sunlight. This softens the harsh shadows by using the sky as a huge light box. A very good friend can also be used to block direct sunlight.
  • Add fill light into the shadows. Some reflectors come with gold, silver, white and black sides giving more options.

2. Fill Light using Off Camera Flash

 

This technique requires an off camera flash. It is also helpful to have a remote shutter release although a 2 or 10 second time delay can also be used.

The off camera flash can be either wired or wireless. Wired TTL extenders come in lengths from 1.5' to 33'. They can be purchased from a variety of sources and price points. Camera Stop and Cowboy Studio also carry them. Remote wireless flash come in a variety of forms. Major brands and and less expensive third party brands are available. Most use Infra Red signaling susceptible to shadow blockage. The newer flash models use radio which can see "around corners".

Remote shutter releases also come in wired and wireless versions. Almost all of the wireless versions use radio technology.

Here are two examples of fill flash taken at the Dallas Arboretum:

Focus Stacking for Effect

Focus stacking is designed to solve problems we have with limited "depth of field" available with our lenses. The two challenges we are interested in are taking pictures of flowers and scenes.

With flowers we would like to capture all the detail and beauty of the flower while letting the backgound soften to a blur. While we could easily capture the flower with a large f stop, say f / 11 or f / 16, that would render the background distractingly sharp. But if a lower f stop is used then only part of the flower is in focus.

The solution is to move the focal plane through the flower either by changing the lens focus or physically moving the camera. The sharp portions of the each image can then be extracted to a new composite using software. The images can be "stacked" using Adobe Elements, Adobe Photoshop, Helicon Focus, and Zerene Stacker among others.

Typically the camera is controlled electronically using Helicon Remote, Camranger, or Promote control. The disadvantage is extra equipment must be carried in addition to the tripod. A manual focus stacking technique is discussed below.

Macro Photography

 

Many times the subject too close for the lens to focus. In this case we use additional hardware to enable the lens to focuse closer. Effectively we shift the focus distance range from, say, two feet to infinity to one foot to five hundred feet. This is a problem that can happen with all lenses including macro lenses. The two methods are extension tubes and close-up diopter lenses.

Extension tubes are the least expensive way to add a macro capability to any lens. They have been used on a 600mm lens with a 2x doubler to make a 1200mm "macro" lens. The frog below is a 700mm macro. A 48mm extension tube was als used to focus "really close".

FL: 420.0 mm (35 mm equivalent: 659.5 mm); Camera: Canon EOS 7D;
Exposure: 1/3200 @ F / 8; Lens: EF300mm f/2.8L IS USM +1.4x;

Extension tubes have also been used on macro lenses to bring the subject in a little closer. They typically come in a set of 3. Kenko has 12mm, 20mm, and 36mm. Don't go on a trip without them!

Close-up add-on diopter lenses are more expensive and not as flexible. They screw on the lens in place of the filter. Consequently, a different filter is required for each lens filter size. With diopters ranging from +1 to +10 and prices ranging form $7 to more than $200 this can be an expensive solution.

Advantages of Using Extension Tubes for Macro Photography

  • Extension tubes are inexpensive when compared to a dedicated macro lens.
  • Different combinations of extension tubes allow you to get a wide range of magnifications with a single lens.
  • Extension tubes do not have any glass elements and so they do not degrade the optical quality of your lens.
  • The brand of extension tube is not important as they do not affect picture quality.

Disadvantages of Using Extension Tubes for Macro Photography

  • They do not work well with lenses of longer focal length.
  • Your lens loses the ability to focus on distant objects with extension tubes mounted between the camera and the lens.
  • They increase the effective f stop of your lens.
  • Extension Tubes are rather awkward to use, to obtain different magnifications one should dis-assemble the set up add/remove tubes and then re-assemble everything. This along with focusing movement is how particular magnifications are obtained.
  • Frequently taking of the lens and putting it back again raises the risk of dust settling on your camera sensor
  • Not all lenses perform well when used with extension tubes some zoom lenses and macro lenses requires their rear element to be at a fixed distance from the sensor for optimum image quality.
  • If you need feature like exposure, aperture, auto focus etc to work; you will need to buy auto extension tubes and they are more expensive.

Google "Close-up diopter vs extension tube" for more information.

3 Hand Held Focus Stacking

One early morning in Cloudcroft, New Mexico, while everyone else was sleeping, I decided to photograph small mountain flowers. I did not bring a tripod or a macro lens. I did have Kenko extension tubes and a 70-300mm zoom lens.

From earlier experience I knew neither Helicon Focus nor Zerene Stacker would align the images. But Adobe's Photoshop and Elements "Auto Alignment" feature is second to none. Just load all the images into a stack, select all the layers, then "Edit / Auto Align Layers". The "Auto Blend" command can generally make the final image. But if not, export the layers into seperate files for further processing in Helicon Focus or Zerene Stacker.

Images are captured as the focus plane moves through the flower. The camera is set to "rapid fire". Then, using either the lens focus control or mechanically moving the camera back and forth, a sequence of images is captured. This technique can be used with or without a tripod. Without a tripod either manually adjusting the focus or mechanically moving the camera is possible. On a tripod only adjusting the focus is possible (unless a slide 24" roller rail is available).

The advantage of this technique is no additional electronic equipment is required. The disadvantage there may not be sufficient overlap in the depth of field focus planes. i.e., some planes may be soft focused. To minimize this effect, at 5 frames a second it will take about three seconds to focus scan the flower.

The caveat of any focus stacking technique is, with or without wind, the flower petals must not move from frame to frame. Rigid tulips are easy. Fluttering daisys are impossible.

Below are three focus stacked images taken without a tripod. The technique is to rock up and down until the focus is just above and just below the object. With the camera in high speed auto trigger, slowly drill down through the range. Depending on how large the object is, there will be between 4 to 30 images.

In a recent development, Zerene Stacker's recent release significantly improved the image alignment algorythms. The yellow flower below was aligned and processed with Zerene Stacker.

 

FL: 300.0 mm (35 mm equivalent: 291.2 mm); Camera: Canon EOS 5D Mark III; Exposure: 1/125 @ F / 8; Lens: EF70-300mm f/4-5.6L IS USM;
Kenko Extension Tubes: 48mm

4 Focus Stacking using a Macro Rail

A focus rail was used for this image. At f / 3.2 a total of 26 slices were required to capture the entire iris. Post processing was completed with Helicon Focus. F / 3.2 was required to soften the back ground.

Canon 5D Mii; Canon EF100mm f/2.8 L Macro; ISO 400; 1/320 sec @ f / 3.2

5 Focus Stacking using Helicon Remote

This is a carnation in the kitchen. The focal plane can be easily seen moving from front to back. The f / 2.8 aperture is required to suitably blur the background. The three other red flowers were blurred by "painting in" information from the first image. Zerene Stacker was used.

Canon EOS 7D; 100.0 mm (35 mm equivalent: 157.0 mm) ;
EF100mm f/2.8L Macro IS USM; Focus Distance: 0.7 m; 1/20 @ f / 2.8

Below is a scene out the kitchen window. The scene stretches from about 5' to infinity. At F / 2.8, 30 exposures were used for illustration purposes. For a scene such as this we should have used f / 8 or f / 11 with many fewer images. The scenes in the three images below were captured with Helicon Remote. F / 2.8 was used for illustration purposes. It is apparent that 10 to 15 images were not required because the focus point is on the invisible lawn between the near hedge and the lot across the street.

Focus Dist: 2.06 m - infinity; Hyperfocal Distance: 186.66 m;
FL: 100.0 mm (35 mm equivalent: 157.0 mm); Camera: Canon EOS 7D;
Exposure 1/100 @ F / 2.8; Lens: EF100mm f/2.8L Macro IS USM;

In the image below, only six images were taken. Artifacts around the foreground leaves are readily apparent.

Focus Dist: 2.06 m to infinity; Hyperfocal Distance: 186.66 m;
FL: 100.0 mm (35 mm equivalent: 157.0 mm); Camera: Canon EOS 7D;
Exposure: 1/100 * F / 2.8; Lens: EF100mm f/2.8L Macro IS USM;

In the image below is similar to that above but at f / 32. Notice the lack of edge artifacts surrounding the foreground leaves as was obvious at f / 2.8 above. F / 32 is a bit much. As a practical matter, f / 8 to f / 16 would have been a better cloice. This would maximize the sharpness by minimizing edge diffraction through the aperture. Also note the change in the hyperfocal distance due to the reduced aperture.

Focus Dist: 2.06 m to infinity; Hyperfocal Distance: 16.33 m;
FL: 100.0 mm (35 mm equivalent: 157.0 mm); Camera: Canon EOS 7D;
Exposure: 0.3 sec @ F / 32; Lens: EF100mm f/2.8L Macro IS USM;