Whenever I have taken macro-photographs, the depth-of-field is always very shallow.
The image below is of a bee that I photographed on my allotment last year using a Nikon D90 with a Sigma 105mm macro lens with the aperture set wide open at f 2.8.
Only the base of the antennae and the eyes of the bee are sharply focussed the rest of the image is very soft.
The depth-of-field can be increased by closing the aperture but this has the effect of reducing the amount a light into the camera. this is always a difficult compromise with macro photography.
Although this image is well lit, the subject was in the shade and this is why I had to have the aperture set wide open at f 2.8
I have been experimenting with the macro-photography of insects for almost 6 years now.
I have found that it is possible with some lenses to attain a relatively deep depth of field providing that an external source of light can be used such as a ring-flash which I normally use.
Using a ring-flash allows me to close the aperture of the lens right down as far as it will go whilst still putting enough light onto my subject.
After many years of photographing in this manner, I have honestly felt that I am not able to advance my technique anymore in terms of the level of detail that I am able to achieve.
I have known for many years about the technique of Focus Stacking or Focal Plane Merging and this is something that I definitely want to incorporate into my final project.
As this is my Final Project, I want these macro images to be the best that I have ever taken.
This is a technique where a series of images of the same subject are taken from the position with the camera mounted in a stationary position on a tripod.
Starting from the front of the subject/the part of the subject closest to the camera, the focus point is moved between each exposure through the image.
Effectively focussing from the front to the back of the image.
This resultant set or stack of images are then blended together either by hand or by an automated process to produce what is called a ''stacked image''.
This ''stacked'' image will be perfectly focussed throughout the shot.
This gives the photographer full control over the amount of the image that they wish to have in focus and can result in infinite depth of field within an image as it can be perfectly focussed from front to back.
Helicon Soft
The Helicon Soft Website:
I was introduced to this programme about a year ago by my technical demonstrator at University.
Until the start of my Negotiated Major Photographic Project, I had only researched this software and looked at the website. I had no actual experience of using it and in fact, had never attempted photo-stacking before.
For this module, I decided that I wanted to produce the best macro-insect photography that I have ever done.
This was very ambitious but I knew that if I could make it work that I could achieve some spectacular results.
After looking through the website, it appeared that there were two main elements that I would require.
These are as follows.
1. Helicon Remote.
This is the programme that is the interface between the computer and the camera that is used to control the camera whilst generating the stack of images.
1. The Helicon Remote Programme.
2. Helicon Focus.
This is the programme that renders the stack of images together into a single image.
2. The Helicon Focus Programme.
After further reading on the Helicon website, it appeared that there was a free 30-day trial of the full-version of these 2 programmes so I immediately downloaded them to my computer.
Using Helicon Focus.
Fig-1
As an example, in figure 1, I have taken a single image of some coins using a macro lens close up with the aperture at f 2.8.
I want all of the elements in this image to be sharply focussed.
Only the right side and the top of the pound-coin are sharply focussed.
The coins behind the pound coin are very softly focussed.
The image in the live-view can be slightly mis-leading and can make the depth of field look even more shallow, this can be easily managed though with the preview option at the top of the screen that takes a temporary shot for the user to view. This temporary shot is not saved to the computer's memory but should the user want to take a single image, it is possible to take a single image using the ''take photo'' option.
In order to rectify this, I have used the focus stacking technique to take a series of images that are focussed throughout the depth of the entire shot.
Fig-2
In Figure 2. I have used the option to create a new stack.This is just a new empty folder for these images to got into and really helps with the management of my file structure.
By default, the folder is labelled with the date and a sequential number.
Fig-3
Figure 3 shows a close-up view of the control panel on the right side of the screen.
The camera is connected to the computer via a USB cable.
Once connected, this control panel gives the user access to all of the basic camera controls including shutter speed, aperture, ISO, exposure compensation and file type and quality as can be seen in Fig 4.
Adjustment to the white balance is located on the advanced settings tab further down the screen.
Fig-4.
Using the ''Live-View'' mode on the screen, the correct exposure for the shot can be set.
The camera will only work in full-manual mode and not in automatic or either of the priority modes.
Fig-5.
Once the exposure is correctly set.
The user needs to define the start-point for the programme.
To do this, the lens must be set to autofocus so that the computer is able to adjust it.
In Figure 5, there are a series of 3 value arrows. 3 pointing to the left and 3 pointing to the right.
These are used to adjust the focus of the lens to define the start and end points for the programme.
The single arrows perform a very small adjustment to the focus and the 3 arrows make a large adjustment to the focus.
To set the start point, I use the manual focus ring on the lens to override the autofocus and to carefully zoom out so that the front element of my images is only just out of focus.
Once I have done this, I click on the A button in Fig 5 and set the ''start-point''.
I then use the 3 blue arrows pointing to the right to adjust the focus right through the shot until the last element at the back of the image has just gone out of focus.
Once I have done this, I press the B button to define my ''end-point''.
Once this is done, I press the ''start-shooting'' button at the top of the screen.
This takes control of the camera and focusses the lens back to the start-point-A that i have pre-defined and then starts to take the series/stack of images.
In this instance, the programme has made the calculation that it needs to take 51 single images to ensure that the distance between the 2 focal points that I have specified at point A and point B will be perfectly focusses.
Once this is done. I need to render or stack this series of images into the single image using the Helicon Focus Programme.
Helicon Focus.
To render the stack of images into a single image, they are first imported into Helicon Focus using the ''add-files'' tab at the top left corner of the screen as can be seen in Figure 6.
Clicking this tab opens my file directory and I am able to select the relevant folder of images.
By clicking on one of the images in the folder and using the command-A to select all, this ensures that I have selected all of the images within the folder.
Once they are imported into Helicon Focus, I press the ''render'' button at the top right corner of the screen and this starts the rendering process.
Once it is complete, I am presented with a preview of the final, stacked image as seen in Figure 8.
It is then possible to save the file in a number of different formats.
Fig 6.
Fig 7.
Fig-8.
The final rendered image in Figure 8 is a composite of 51 seperate images !
It is focussed all of the way through compared to the initial image in Figure 9 below.
Figure 9.
This is a link to a tutorial on focus-stacking that is on the Helicon website and I found it to be an excellent way to learn the process.
From my research online, I have found out that it is also possible to stack the images in Adobe Photoshop.
I have found a great tutorial on how to do this on YouTube
Link to You Tube Focus Stacking in Photoshop Tuotrial.
A tutorial on advanced sharpening techniques.
Advanced Sharpening Techniques in Photoshop CS6
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