What is Minimum Focus Distance

The minimum focus distance is the closest distance from the focal plane, the sensor, to the subject at which the lens is able achieve focus. If you get closer than the minimum focus distance the lens will NOT be able to focus on the subject. This typically happens when you try to take close up pictures, for example of flowers, insects or jewelry.

The minimum focus distance is lens dependent and the value can be found, usually specified in feet and meters, via the manufacturer specifications for the lens of interest. For example the Canon 100mm F/2.8 IS macro lens has a minimum focus distance of 0.99ft or 0.3m.

The minimum focus distance is measured from the focal plane, the sensor (NOT the front of the lens), to the subject. The sensor position in your camera is typically marked on the outside of the camera body with a line through a circle symbol, which is the starting point of the measurement.

Some lenses have switches to limit the minimum focus distance so the the camera cannot focus on objects close to the camera. For example, if you wanted to take a portrait of someone through tall grass. In this case you would not want the camera to be able to focus on the close objects, the grass, just on the subject you are trying to take the portrait of.

In our next lesson we will discuss “plane of focus” which is related to a previously discussed topic “Depth of Field“.

Raw vs. Jpeg Image Quality

From our last lesson about “camera image resolution” that the size of the image is based on the camera sensor type and specifications, and is where the light is captured and converted into a digital image.

Image quality set to “RAW”

Not all cameras have the feature to capture images in “RAW” format, check your camera image quality settings to see if its an available option.

When the captured “image” is read directly from the sensor and then stored on the camera’s memory card without any conversion or processing, the saved “RAW” file is commonly referred to as a read-only digital negative. The “RAW” format is a proprietary format for each camera manufacturer and camera model.

From the diagram below we see that the camera settings influence the Jpeg preview that is processed from the RAW file which then gets added to the RAW file before being stored on the memory card.

Advantages with image quality set to “RAW“:
■ Maximum amount of digital information captured in the image (higher dynamic range)
■ White balance colour values in “Kelvin”
■ More than 8 bits of colour
■ Uncompressed (lossless)
■ Read-only Digital Negative

Disadvantages with image quality set to “RAW“:
■ Every image requires post-processing
■ Large files, require more storage space
■ Images take longer to upload from the memory card to the computer
■ Limits the number of images captured in burst mode
■ Requires conversion/processing before being printed

There are many who say you must shoot in “RAW”. While choosing to shoot in “RAW” does give you the most amount of information, it is not always necessary or advantageous to use the “RAW” image quality setting, because it depends on what you are shooting. For example, if you were taking images at a sporting event and the images need to be published immediately then “RAW” is probably not the best choice. However, if your are taking landscapes then “RAW” would be the best choice.

Image quality set to “Jpeg”

The “Jpeg” quality setting is typically the standard default setting for your camera. It is important to understand that your camera settings apply post-processing to your image that is stored on the memory card.

From the diagram below we see that the camera settings and the camera image processor generate the Jpeg image from the sensor RAW information. The result of the camera processing is stored as a compressed “Jpeg” image on the memory card.

Advantages with image quality set to “Jpeg”:
■ Standard image file format
■ Smaller files, less storage space
■ Share directly to social media
■ Directly to print
■ Camera settings applied directly to image (post-processing)

Disadvantages with image quality set to “Jpeg“:
■ Limited dynamic range
■ Camera settings applied directly to image
■ Colour temperature applied directly to image
■ Compressed (lossy)
■ 8 bits of colour

My humble opinion it takes great skill to successfully shoot with the “Jpeg” image quality setting. From knowing how the camera settings directly affect the captured image to getting an exposure that looks good right out of camera is challenging even for the most skilled photographer. For example, some of the best photographers in the world shoot with “Jpeg” image quality at the Olympics as they have their cameras directly connected to the wire service that gets an image out to the media, on average, within 90 – 120 seconds of the image being taken.

You as the photographer need to decide how far you want to go based on what genre you are shooting, how your image will be used, who the image is for, and how much time and resources you want to spend on each image. Choose the right image quality setting that meets your needs.

In our next lesson we will discuss what minimum focus distance means.

Camera Image Resolution and Settings

When initially setting up your camera, an important consideration is to choose the image resolution setting which determines what image size will be recorded to the cameras memory card.

The sensor in your camera is specified in megapixels which is simply the number of pixels in width times the number of pixels in height of your sensor. For example a Canon T6i camera, from the manual specifications page 384, the “L (Large)” setting records an image from the sensor as 6000 pixels in width by 4000 pixels in height. If we multiply those two numbers; 6000x 4000=24,000,000, results in a total of 24 million pixels, commonly referred to as 24 megapixels (mega meaning million). The T6i uses an APS-C sensor, the 24 million pixels fit within an area 22.5mm wide x 15mm high (see APS-C Canon in the Sensor Comparisons diagram below).

The “Large” setting on most cameras is a best fit that maximizes the number of pixels that can be recorded by the camera sensor. It is recommended to set your camera to the “Large” setting.

To Set the image recording quality for the Canon T6i refer to the manual on page 115. There are two (2) settings to consider; 1. image quality (includes image type Jpeg or RAW), and 2. aspect ratio.

As an example, the Canon T6i image quality settings are shown in the table below. If you want to shoot with the highest quality Jpeg; 1. press the menu button, 2. under the “camera 1” tab select “Image Quality” using the “▲” and “▼” buttons then pressing “Set”, 3. Select the first “Large” option using the “◄” and “►” buttons and then pressing “Set”.

As an example, if you want to shoot in RAW on the Canon T6i; 1. press the menu button, 2. under the “camera 1” tab select “Image Quality” using the “▲” and “▼” buttons then pressing “Set”, 3. Select the “RAW” option using the “◄” and “►” buttons and then pressing “Set”.

The aspect ratios available on the Canon T6i are; 3:2, 4:3, 16:9, and 1:1. To many this is a confusing topic however, it is simply the relationship between the width and the height broken down to the lowest whole number. Lets do a few examples with some basic math.

Example 1: Let’s take the Jpeg “Large” size for the Canon T6i from the table above, we see that the pixel size is 6000 pixels wide and 4000 pixels high a 6000:4000 ratio. So now lets simplify it; if we divide 6000 by 1000 we end up with 6 and if we divide 4000 by 1000 we get 4 which leaves us with a 6:4 ratio (notice we are dividing each number by the same number 1000). Lets simplify it further; if we divide 6 by 2 we get 3 and if we divide 4 by 2 we get 2 which leaves us with a 3:2 ratio. Hopefully you now see that 6000:4000, 6:4, and 3:2 are all the same ratio, we usually specify the ratio with the smallest whole numbers in this case 3:2, also note that 3 divided by 2 equals 1.5 and from this number we can make up a table for each ratio to use as a lookup to more quickly identify the ratio.

Example 2: If we take the 4:3 ratio and divide 4 by 3 we get 1.333. Now lets take the “Large” 4:3 pixel values from the table above; 5328 pixels wide by 4000 pixels high. Lets divide 5328 by 4000, the result is 1.332 which we see is very close to 1.333. Hopefully you now see how to simplify the determination of the image ratio when you know the pixel width and pixel height.

As an example, if you want to change the aspect ratio setting on the Canon T6i; 1. press the menu button, 2. under the “camera 3” tab select “Aspect ratio” using the “▲” and “▼” buttons then pressing “Set”, 3. Select the desired Aspect ratio “3:2, 4:3, 16:9, or 1:1” using the “▲” and “▼” buttons and then pressing “Set”.

From the diagram/table below we can see the “result” of dividing the width by the height for various ratios. Use this table as a lookup table to help with figuring out the ratio when you know the width and height of the camera sensor or digital image, with the method shown in “example 2”.

One more thing about “ratio”. Looking at the Canon T6i image quality size comparison table below lets compare the the “Large” values for the various available ratios. Notice that the 3:2 ratio results in the largest size image while the 1:1 ratio results in the smallest size image. Typically its best to choose the ratio with the highest image size and crop the image later in post processing. However, if you are shooting in Jpeg and want to be able to go directly to print you can set the aspect ratio to meet your needs. “A word of caution, if you are changing the aspect ratio be aware that it may not always fit your shooting scenario so remember to set it to the desired aspect ratio before you start shooting”. You can always shoot with a 3:2 ratio and use the Kiosk when submitting your images to be printed at a photo lab which allows you to crop your images, however, you could end up cutting of parts of the photograph as the image when shot may not have left enough room for the print size chosen.

Take some time to go over this lesson there is a lot of information here and it does take some time to digest. In our next lesson we will discuss the differences between shooting in Jpeg vs RAW.

Camera Colour Space Setting

Colour Space is simply a definition of reproducible colours, typically shown on a graph in relation to the human eye. The four (4) most common colour spaces are; sRGB, Adobe RGB, CMYK, and ProPhoto RGB.

sRGB is the colour space used for images on the internet and for digital displays (monitors) and represents about 50% of the range or colours that the human eye can see. sRGB is the most common (default) colour space used by photo labs for producing prints.

Typically, any camera which only shoot Jpeg images will not have a choice of colour space setting in the camera and defaults to sRGB.

A camera that has the ability to shoot in RAW will typically provide the ability to choose between sRGB or Adobe RGB. As seen in the diagram Adobe RGB covers a wider range of colours than sRGB and covers a range about 75% of what the human eye can see.

It is always best to set the camera to the highest quality colour space setting , Adobe RGB, to maximize the amount of colour information in your captured images. The conversion to sRGB for printing takes place during image exporting using post processing software. It is important to note, if you do not use post processing software the colour space setting should be set to sRGB to allow for proper printing and displaying of your images.

On a Canon T6i the setting, refer to page 146 in the manual,  is located in the camera menu under the second camera tab. Select Color space, then choose Adobe RGB if you use post processing software otherwise choose sRGB.

On a Nikon D5100 the setting, refer to page 10 in the manual. Start by pressing the menu button, then select shooting menu, choose color space and then select Adobe RGB if you use post processing software otherwise choose sRGB.

In our next lesson we will discuss setting the camera’s image resolution.