The Small Groups calculator is used when you are photographing small groups of people arranged into two or three rows.

How many rows should you use?
How many people in each row?

In making these decisions you want to wherever possible:

• Have alternating even and odd rows of people, so that each person can be positioned in the gap between the heads of the people the row in front of them.
• Make the group as a whole symmetrical.
• Have a similar number of people in each row, so that the group fills the frame.

The Small Groups calculator will help you decide how many rows to use, and how many people in each row while wherever possible meeting these goals.

Small groups are typically limited to less than 40 people, as above this size the group becomes too wide and more rows need to be added. For groups larger than this use the Big Groups Calculator.

Read more: Small Groups Calculator

The keystone calculator is used when you are photographing a large group of people in an open area with the camera in an elevated position. 

For example, your local school is celebrating its 50th anniversary and wants you to take a photo of 434 students arranged in the shape of "50" on their playing field with the camera in a cherry picker or upstairs window. 

How big does the “50” need to be to fit in all 434 students?
How do you compensate for the keystone effect so that the "50" looks straight in the frame?
How high does the camera need to be?

The Keystone Calculator will help you answer these and other questions.

For an explanation of the Keystone Effect see What is the Keystone Effect.

Read more: Keystone Calculator

The Big Groups calculator is used when you are photographing large groups of people on tiered stands.

How many rows should you use?
How many people in each row to produce a group that fits well in the frame?

In making these decisions you also want to, wherever possible:

• have alternating even and odd rows of people, so that each person can be positioned in the gap between the heads of the people the row in front of them
• make the group as a whole symmetrical
• have the number of people in each row is similar, so that the group fills the frame.

The Big Groups calculator will help you decide how many rows to use, and how many people in each row while wherever possible meeting these goals.

For groups smaller than 40 people use the Small Groups Calculator.

Read more: Big Groups Calculator

This section describes the default settings that can be changed. In the Pro version all of these values can be changed. In the Free version, only the Measurement Units can be changed. 

General Display Settings

Default Display

Sets which calculator is to be displayed when GroupCalc is first started. Values are:

• Small Groups Calculator
• Big Groups Calculator (default)
• Keystone Calculator

Big Stands Calculator Settings

Default Posing Style

Sets the default posing style to be used. Valid values are:

• Square (default)
• Pyramid

See Big Stands Overview for more information.

Keystone Calculator Settings

Shape to be Drawn

Sets the default shape to be drawn. Valid values are:

• Rectangle
• Two Numbers. The numbers to be drawn are the last numbers used in the calculator. If no previous numbers have been used then "88" is used.
• Custom Shape. The custom shape to be used is the last custom shape that was saved.

See How to Use the Keystone Calculator for more information.

Lens Focal Length (mm)

The default camera focal length to use. The initial default value is 35mm.

See Focal Length for more information.

Tilt Angle (degrees)

The default camera tilt angle to use. The initial default value is 45^o.

See Camera Tilt for more information.

Frame Border (%)

Sets the default frame border to use. The initial default value is 15%.

See Border for more information.

People Density

The default number of people per square metre. The initial default value is 3.0 people/m².

See People Density for more information.

IMPORTANT NOTE: If you have changed the Measurement Units (see below) then you must enter the people density in those units. For example, if you have changed the Measurement Units to "Feet" then you must enter the people density in people per square foot.

Results Precision

Changes the number of decimal places that are shown in Keystone calculator results. Valid values are 1 decimal place (.0) or 2 decimal places (.00).

The default is 1 decimal place on phones, and 2 decimal places on tablets.

Transparent Ruler

Sets whether the centre ruler is semi-transparent to allow the underlying shape to be seen, or solid for improved readability.

The default is semi-transparent.

Measurement Units

Changes the units in which calculated lengths will be displayed, and the units in which the People Density must be entered. Valid values are:

• Metres (default)
• Feet
• Yards

Calculation Mode

Determines the way in which keystone calculations are done. Valid values are:

• Safe (default)
• Exact

In Exact calculation mode the keystone distortion and group area are calculated exactly as based on the input values you have set.

In Safe mode the amount of keystone distortion is artificially reduced from the value that would be calculated in Exact mode. This is done to give an increased margin of error when marking out your group shape and positioning the camera.

When marking out a group shape and positioning the camera it is not always possible to get the camera at exactly the right height and angle, and to mark out the group exactly. When this happens it is generally better to underestimate the amount of keystone distortion than to overestimate it.

The eye is used to seeing lines receding into the distance so if a group is a little too narrow at the back (because not enough adjustment was made for keystone distortion) then the viewer tends to see this as looking acceptable.

If too much adjustment is made for keystone distortion (i.e. the back looks wider than it should and the front looks narrower than it should) it tends to look "wrong". Using Safe mode reduces the chances of this happening.