Macro Photography Calculator

When shooting large format, especially 8x10 and up, it is easy to fall into the realm of macrophotography. When your "sensor" is 8x10 inches, any subject of ~10 in size will be reproduced with a magnification 1:1, and even a half-body portrait will be reproduced with a substantial magnification of roughly 0.33 to 1.

Image taken at about 1:1 magnification.

When I attempted to take close-up images with my 8x10--which as I explained above is fairly common--some questions arose:

- what lens can I use?

- do I have enough bellows draw to focus close?

- how far from the subject should I position the camera? (8x10 viewcameras are always cumbersome to more around when fully deployed)

- how much light loss should I compensate for?

So, I made a Google sheet that can answer all these questions.

Link (you will have to make a copy of this file to edit it)

How to use the spreadsheet

You need to input these three pieces of information in the yellow boxes:

1. Select your camera format in the drop-down menu.

2. Measure the length of the subject you want to photograph (long side).

3. Input the focal length.

The spreadsheet with tell you:

1. how much bellows draw you need, 

2. how far to place the camera back (film plane) from the subject.

3. how far from the lens plane the subject will be

4. how much light is lost due to magnification (both the stops lost and the multiplication factor for the exposure time).

Additionally, by entering the f-stop used (for example f/32), the spreadsheet will estimate the depth of field.

For convenience, there is one column with imperial units, and one with metric units.