Canon MP-E 65mm f/2.8 1-5x Macro Photo MP-E 65mm F2.8 1-5X MACRO PHOTO Instruc - Page 8

3. Setting the Exposure Magnification and Effective f-number The aperture displayed by the camera assumes that the focus is set to infinity. The actual aperture (effective f-number) becomes darker (effective f-number increases) at closer focusing distances (magnification increases). This does not cause exposure problems for normal picturetaking. However, for closeup photography, you cannot ignore the change in the effective fnumber. When you use a handheld exposure meter to set the exposure, you must take into account the exposure factor shown in the following table. Use the following formula to calculate the effective f-number: Effective f-number = f-number × (Magnification + 1) For example, if the aperture displayed by the camera is f/2.8 and the magnification is 1×, the effective f-number will be f/5.6. Magnification Effective f/No. 1× 2× 3× 4× 5× 5.6 8.4 11.2 14.0 16.8 Setting the Exposure The correct exposure for a close-up shot largely depends on the subject. Therefore, try to bracket the exposure for the same subject. With the EOS-1Ds Mark III, 1Ds Mark II, 1Ds, 1D Mark III, 1D Mark II N, 1D Mark II, 1D, 1, 1N/DP/HS, and 1V/HS TTL autoexposure metering is possible from 1× to 5×. Select the desired picture-taking mode and check the shutter speed and aperture. With Other EOS Cameras Since there will be a slight exposure error, using AE metering is not recommended. Take test shots first or use a handheld meter to determine the proper exposure based on the effective f-number. If you use the f-number displayed by the camera, use the exposure factor in the table below to convert it. Magnification 1× 2× 3× 4× 5× Exposure Factor (stops)* +2 +3 1 3 +2 +3 +4 +4 2 3 +5 1 3 +4 +4 1 2 +5 * Upper values: 1/3 stops. Lower values: 1/2 stops. ENG-7