Description

Standard Edition Lepus 0.62X telecompressor lens designed for use with any telescope having the TCF-S or other 2-inch focuser in place. Works well with Meade ACF f/10 and f/8 coma-free SCT telescopes. The Lepus 0.62X Standard Edition is housed in a 2-inch barrel-like assembly and will fit into any telescope receiver for standard 2-inch eyepieces.

The camera side connection for the Lepus 0.62X telecompressor is a broad dovetail known as the OPTEC-2100. The proper back-focus distance to the camera image plane is maintained with Optec's custom camera-specific Lepus mounts available separately below. The OPTEC-2100 interface also allows easy connection to the Pyxis 2" rotator in place of the standard 2-inch nosepiece. When connected to the camera, Lepus will appear as a long 2-inch nosepiece that fits into any 2-inch focuser or eyepiece receiver.

Special DSLR adapters are available from stock for Canon and Nikon cameras which hold and maintain the 100mm on-axis back-focus distance.

The Lepus can be used with other telescope designs but is not parfocal. Therefore, some re-focusing will be required. Performance is not guaranteed with all telescope optical designs and the Lepus is not recommended for use with Ritchey-Chretien telescopes.

Specifications

Telescope-Side Compatibility:

• TCF 2-inch focuser,
• TCF-3 3-inch focuser with 3" to 2" adapter,
• Any 2-inch focuser or receiver.

Camera-Side Compatibility:

• Lepus camera-specific mount.  See the table below for common camera adapters,
• #19390 and #19393 Variable Length Camera adapters,
• Pyxis 2" camera field rotator (between telecompressor and camera),
• Any OPTEC-2100 receiver.

Camera Mount Required:

Note that the #19407 Lepus - Standard Edition does not include a camera specific mount.  Be sure to order one of the Variable Length Camera mounts 

Back-Focus Diagram:
#19407 Lepus 0.62X - Standard Edition diagram showing the optimal back-focus distance to image sensor.

Lepus Mounting Plates

Camera-Specific Mounts for the Lepus Telecompressor

The Lepus telecompressor has a design back-focus distance of 100mm on-axis. Each of the camera mounting plates below are designed to maintain that back-focus for the best overall image quality and a reduction of 0.62X. Varying the back-focus distance will alter the magnification (reduction) but may introduce undesirable optical aberrations as well. We recommend using the Lepus telecompressor only with the recommended camera-specific mount.

Each camera mount consists of a 2.1" ID tube of various lengths and a mechanical interface such as a T-thread, C-mount, or STL thread. This ID tube fits over the camera side of the Lepus telecompressor, which features the OPTEC-2100 male circular dovetail mount. The camera mount is held securely to the Lepus dovetail using three oval point setscrews located 120 degrees apart. 

It is important that the overall back-focus distance be set as closely as possible to the design distance of 100mm on-axis. Measured from the flange at the bottom of the OPTEC-2100 dovetail, the distance works out to 105mm as shown in the PDF at left. 

Most of the mechanical camera interfaces require an additional 1/10th inch or 2.5mm of back-focus. The camera backfocus distance, BF, should be known to within about 1mm for best performance and should include the thickness of any filter wheel, off-axis guider or other adapter between the Lepus and camera sensor. Use the table below to find the appropriate mounting plate for many commercially available cameras and configurations. If your camera is not listed below and you know the optical back-focus, BF, and mechanical interface (i.e. T-thread) you can determine the stock number as with the following calculation:

TUBE LENGTH = 105mm - FLANGE THICKNESS - CAMERA BACK-FOCUS

Next use the TUBE LENGTH value calculation above for the suffix.  For example, nearly all C-mount cameras share a 17.5mm BACK-FOCUS value. The C-mount stock number prefix is #19399 and the TUBE LENGTH would be equal to 105mm - 2.5mm - 17.5mm = 85mm.  The Optec stock number for a C-mount camera would therefore be  #19399-85 as shown in the table below.

NOTE:  The minimum tube length is limited by the height of the OPTEC-2100 dovetail plus the press-flange of the mechanical mount (usually about 0.2" or 5mm).  The standard Lepus telecomprssor minimum tube length is 15mm while the Edge HD specific Lepus telecompressor is 17mm.

Reference Table of Camera-Specific Mounts

* denotes vignetting may occur with Lepus telecompressor.

Questions?

Feel free to call Optec for any camera not listed or with any questions regarding back-focus, camera mounts, and Lepus performance in general.