The VESPID SERIES lenses are adjusted for back focus according to standards before leaving the factory, but flange distances of different cameras may have slight differences, resulting in inaccurate scales. To match different cameras and achieve the best imaging effects, back focus adjustment and calibration of the scale are required.

1. Preparation

The following operations take the Vespid Cyber 35mm lens as an example

Step 1: Prepare the subject. You can use the "Star Chart", or use other black-and-white, high-contrast subjects. Download the "Prime Lens Back Focus Calibration Tool" on the official website (click here to jump)

Tip: You can go to "DZOFILM Official Website - Support - Download Center - Tools - Back Focus Adjustment Lens - Back Focus Adjustment Star Chart" to download (click here to jump)

Step 2: Mount the lens on the camera or video camera and adjust the aperture to T4.

Step 3: Attach the "Prime Lens Back Focus Calibration Tool" to the 1.6m focus mark (or choose another focus mark line at a distance of 1.6m), aligning the scale pointer with the middle horizontal line of the "Prime Lens Back Focus Calibration Tool".

Step 4: Place the subject at approximately 1.6 meters from the flange distance, and adjust it to be in the center of the screen.

Place the subject at approximately 1.6m from the "Φ" mark of the camera's image plane, keeping the subject in the center of the screen.

2. Adjusting Back Focus

For the adjustment process, please follow the steps below

Step 1: Rotate the focus ring until the image reaches a clear state. Using the middle horizontal line of the "Prime Lens Back Focus Calibration Tool" as a reference, observe the position of the scale pointer at this moment, and note the number of horizontal lines the scale pointer is offset by.

Tip: If it deviates towards infinity, it represents a positive scale offset value.

If it deviates towards the closest focusing distance, it represents a negative scale offset value.

If it exceeds five grid lines, simply add or subtract the corresponding values.

Example: If the scale pointer points to a scale line that is offset by 5 grids towards the closest focusing distance, the scale offset value is -5.

If the scale pointer points to a scale line that is offset by 5 grids towards infinity, the scale offset value is +5. In this case, you need to add a "+1" shim value to the "+4" shim value.

Step 2: According to the scale offset value, refer to the table below to adjust the corresponding shims to complete the back focus adjustment.

Tip: In the back focus shim adjustment values, "+" represents increasing the shim thickness, and "-" represents decreasing the shim thickness.