Description

Lepus 0.62X telecompressor lens designed especially for use with the Celestron EdgeHD C11 OTA. A large 3-1/4 -inch Celestron thread screws directly on to the rear cell thread of the C1100 EdgeHD telescope. 

For use with any Lepus or VLC camera mount having the OPTEC-2100 2.1-inch dovetail receiver. 

See Lepus Camera Mount table below for recommended length camera mount. 

Specifications

Telescope-Side Compatibility:

• fits Celestron 3-1/4" male thread.

Camera-Side Compatibility:

• Lepus camera-specific mount.  See the table below for supported cameras.

Back-Focus Diagram:
#19411 Lepus-HD C11 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.