Camera settings and specifications
Table of contents
Once you have decided on which camera you are going to use and have received it, ensure you are familiar with how it works. Each make of camera will be different, but make sure you take the time to get to know yours before using it for acquiring specimen photos. Here is a checklist of things to do before taking images of specimens:
1) Set the date and time. Make sure these are correct – affects file naming (see below).
2) If available, set up sensor cleaning.
3) Work out how to access the manual controls of the camera - this will probably involve taking it out of “P” or “Programme” mode and selecting “M” for “Manual”. You will want to be able to alter:
a - ISO sensitivity
b - White balance
c - Shutter speed
d - Aperture
e - Focus
4) Set the output image format. It is strongly recommended to set this to the Raw format.
5) Set the file naming protocol. A numbering system that determines how each file taken will be saved. Recommend setting this to the format YYYY-MM-DD. With this format the name of every picture taken on the 10th of January 2022 will start 2022-01-10. Photos will then be tagged with a number indicating which picture they were taken on that day. For example, the first photo will be 2022-01-10-00001, the 30th will be 2022-01-10-00030, and the 258th will be 2022-01-10-00258. This makes it easy to find pictures if you know on which day they were taken and will automatically organise the files when sorting them by name as all photos with the same prefix will group. Additionally, if you are using multiple cameras at the same time you should include a camera body identifier in file names, otherwise you could get duplicated file names. Consistent file naming is essential for data management and sharing (see data mobilisation module).
6) Cables – check you have the necessary cables to connect your camera to both: 1) the mains power; 2) and to your computer. Cables are often standardised between makes and models, but its worth checking that your camera and computer are compatible with your connecting cables. This is especially crucial if equipment is updated as cable ports unfortunately change over time.
Details on how to do each of these steps should be found in the manual included with your camera. If you have lost your manual they can be often found online. Partiualry useful is youtube which contains several videos of how to use some of the main camera brands Check https://www.butkus.org/chinon/ which has a wide range of downloadable camera manuals.
Resolution
The quality and clarity of an image is determined by its resolution. Digital images are displayed on screens using pixels, and the image displayed is created by controlling the colour/brightness of each pixel. The more pixels making up a screen, the more fine detail the image can depict. Below we have a series of images of different resolutions each attempting to show the same letter R.
Figure18: Same image different resolutions Wikimedia Commons.
Here we have a series of square images composed of different numbers of pixels. The numbers above each picture indicate the length and breadth of each image in pixels.
We can see how the clarity of the image increases from left to right. The right-hand image is composed of 10,000 pixels (100x100) and therefore has a far greater resolution than the other images. In digitisation, we typically want to produce high-resolution images of specimens which contain fine details for analysis and specimen comparison.
For example consider these two similar images showing a specimen of the butterfly Colias hyale:
Figure 2: Two images of Colias hyale, left 50Mp, right 0.046Mp.
These two images were taken with the same camera and with the same settings (1/80, f/10, 400). However, the one on the left is the camera’s RAW format using its maximum resolution (~50Mp). The one on the right was saved as a .jpeg using a much lower resolution (0.046Mp - the camera’s lowest setting). When viewing the two pictures at this scale, they appear very similar - the specimen can be seen clearly and the label is readable. This could tempt us to use the lower resolution since the space taken up by this file is only 1/415 the size of the higher resolution image (164Kb vs 68,216Kb).
However, lower resolution means a loss of finer detail. In the series of images below, the same area of each image is shown comparing the same space in both high and low resolution images.
Figure 3: close ups of the images shown in Figure 10. The top row is the high quality image (~50Mp) and the bottom row is the low quality image (0.046Mp).
The resolution is typically expressed in megapixels, i.e. the number of million pixels the camera has available to create an image. Generally, the greater the number of megapixels available to the camera, the greater quality and clarity the image will have. While the number of megapixels the average camera can utilise has increased greatly in recent times, any image of 12 megapixels or greater is satisfactory for digitisation, although images of at least >20 megapixels are now common.
Although more pixels means better quality images, more pixels also results in larger images, which take up more storage space and are slower to transfer. Also, an increase in image quality may not be observable for some users if their display screen is not also of a high resolution or if the image is not zoomed in enough. When deciding on an image size in megapixels it is important to consider these other factors rather than chasing ever higher numbers of pixels.
Next page: 4. The exposure triangle