The Parameters Calculator makes it easier than ever to set up your camera for infrared reflectography sessions.
It’s designed to help you work out the best object-camera distance and focus settings for your session, and it’s available to download completely free of charge.
How to use the parameters calculator
To get the optimum resolution from the camera, it’s important to set it at the right distance for your object.
If you want to fit the whole of the object in the frame, just enter the longest dimension of your object into the the ‘Field’ box. The minimum distance required will be displayed in the ‘Object Distance’ box. You might like to set the camera slightly further away to give yourself a small border (and a little flexibility).
You might also choose to image a smaller section of the painting at a higher resolution. To calculate your optimum distance for this, enter the size of the area you’d like to image instead of the longest edge, and set the camera at the stated minimum distance.
Please note: Distance measurements should be taken from the front of the camera case to the centre of your object.
Accurate focusing also makes a big difference to the results you’ll see with your camera, and the calculator makes it easier than ever to achieve it.
Just enter the distance you’ve chosen to place the camera from the object into the ‘Distance’ box and the Calculator will provide an initial focus setting. For accuracy and control, Osiris uses a manual focus mechanism, assisted by a ‘fast focus’ read out mode in our software. This makes focusing something of a two-step process.
First, set the lens to the given focus setting using the numbers on the focus rods. Then select a single square with a feature to focus on in the software, and click the Focus button. Then you can visually adjust the focus by adjusting the lens position on the focus rods, or by using the fine focus dial on the front of the lens assembly.
The depth of field refers to how flat your object is. For flat objects, an f/number of f/8 or f/11 is usually appropriate. However, for a non-flat object, measure the depth of field you require and enter this into the ‘Object Depth’ box. The calculator will display an appropriate f/number to use. Just remember that the greater the f/number, the smaller the aperture and more illumination may be required.