Back focus adjustment, Justment unit, Adjustment – JVC VN-V25U User Manual

Page 23

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23

Inner Tripod Base Mounting Screw

Make use of 1/4-20UNC screw. The length of
the mounting screw shall be between 6 mm to
7 mm from the mounting surface.

Caution:

● Using a screw with a length longer than

specified may damage the internal parts of
the camera, while using a length shorter than
specified may cause the camera to fall off.
Use a washer to adjust the length from the
mounting surface.

The CS mount is adjusted to the widest point of
the applicable range by default. When using the
zoom lens or C mount lens, or when the lens
remains out of focus upon using the focus ring,
readjustment is required.

● Follow the method below when necessary to

adjust the back focus.

● In order to adjust the back focus accurately,

do so according to the steps below upon
opening the lens iris using the iris adjustment
and ND filter.
(ND filter is a filter that is used to evenly
reduce the amount of light entering the lens
at all wavelengths.)

● Connect a video monitor to the [MONITOR

OUT] terminal at the rear of the unit, followed
by adjusting as follows.

Fixed focus lens

Adjust when the lens cannot be brought into
focus using the focus ring.

1.

Loosen the back focus fastening screw by
using a Phillips screwdriver and turning it in
the anti-clockwise direction

2.

Shoot the object or a fine pattern that is
farther away than the object

3.

Set the focus ring of the lens to

4.

Turn the back focus adjustment ring to obtain
a sharp focus

5.

Tighten the back focus fastening screw by
turning it in the clockwise direction, and
ensure that it is securely fastened

Zoom lens

Perform the zooming operation (Tele - Wide)
and adjust accordingly if it is out of focus.

1.

Loosen the back focus fastening screw by
using a screwdriver and turning it in the anti-
clockwise direction

2.

Shoot the object or a fine pattern that is
farther away than the object

3.

Set the zoom lens to Tele and turn the lens
focus ring to adjust the focus

4.

Set the zoom lens to Wide and turn the back
focus adjustment ring to adjust the focus

5.

Repeat Steps 3. and 4. for two to three times

6.

Tighten the back focus fastening screw by
turning it in the clockwise direction, and
ensure that it is securely fastened

Back Focus Adjustment

Mounting Plate

Washer

Max. 7 mm
(17/64 inch)
Min. 6 mm
(15/64 inch)

Back Focus Adjustment Ring

Back Focus Fastening
Screw (M2.6)

Lens Focus Ring

Tighten

Loosen

VN-V25U_26U_EN.book Page 23 Monday, January 21, 2008 10:13 AM

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