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William Shaheen | profile | all galleries >> Astronomy >> Optec Lepus 0.62x Focal Reducer Testing tree view | thumbnails | slideshow

Optec Lepus 0.62x Focal Reducer Testing

Testing the Optec Lepus 0.62x Focal Reducer with the 11" Celestron EdgeHD telescope.

The telescope's stock rear Adapter Plate (see EdgeHD diagram) was replaced with an Astro-Physics 2" Visual Back (AP part # ADASCTLC) in order to install the focal reducer as close as possible to the OTA, as recommended by Optec. Note that when inserting the focal reducer, with it's attached camera adapter, the leading edge of the reducer stops at the edge of the internal field flattener. In other words, it's as close as it can get. (Photos to follow.)

I'm pleased to report that, overall, I found the reducer to produce very satisfying images, resulting in a reduction factor of 0.69x, with my particular configuration, although there won't be much choice for other EdgeHD users as the AP adapter is as close as one can get to the OTA.

Update 24-Apr-2011: I resumed testing after resolving several issues having to do with the baseline - i.e., SCT collimation, guide-camera flexure and focuser flexure (yes, the Feather Touch focuser resulted in a slight drift, which was not mirror shift). See 4 images of M57 (Ring Nebula) taken this date - on the 5th row of images, below.

Some coma is noticeable in the lower left corner only and may be due to a tilted plane, which itself may be the result of, again, the leading edge of the reducer stopping at the edge of the internal field flattener. This is being researched with the vendor.

Update 11-May-2011:
Update on the question of the reducer possibly not seating squarely (the leading edge of the reducer stopping at the edge of the internal field flattener), I just received word from Optec that they "have developed a different mounting configuration for the Edge HD scopes. For the C11 HD and C9.25 HD scopes a spacer is required to keep the lens housing from touching the Edge HD retaining ring." . (At the time I ordered mine from OPT, they had the former version in stock.)

Optec is sending me the new lens and housing gratis and I will be testing it in about a week.
(Thanks, Jeff!)

On another note, I've replaced the ST-8300M with a QSI-583wsg - solves a host of flexure issues up and down the imaging train as well as with any mirror flop or guidescope flexure. The Starlight Xpress Lodestar connects easily to the QSI's guideport, given the standard C-mount adapter) and so far I've had no problem locating a guidestar.

Update 19-May-2011:
Received and installed the new lens cell. It eliminates the need for the AP adapter and in fact replaces the Celestron adapter plate, placing it as close as possible to the OTA. Very secure fit. See "New lens cell 19-May-2011" and the M101 image - 10 minutes unbinned. Yields a reduction factor of 0.66x on the 11" EdgeHD.
NGC3628 in Leo - Baseline image - without reducer (f/10) - binned 2x2
NGC3628 in Leo - Baseline image - without reducer (f/10) - binned 2x2
Test with reducer - f/6.9 - unbinned (300 sec.)
Test with reducer - f/6.9 - unbinned (300 sec.)
Test with reducer - f/6.9 - binned 2x2
Test with reducer - f/6.9 - binned 2x2
EdgeHD diagram.jpg
EdgeHD diagram.jpg
Test with reducer - f/6.9 - unbinned (120 sec.)
Test with reducer - f/6.9 - unbinned (120 sec.)
Test with reducer - f/6.9 - unbinned (030 sec.)
Test with reducer - f/6.9 - unbinned (030 sec.)
20110404_M44-f6.9-1x1-000.5s_001-ddp.jpg
20110404_M44-f6.9-1x1-000.5s_001-ddp.jpg
20110404_M44-f6.9-1x1-000.5s_002-ddp.jpg
20110404_M44-f6.9-1x1-000.5s_002-ddp.jpg
20110404_M44-f6.9-1x1-000.5s_003-ddp.jpg
20110404_M44-f6.9-1x1-000.5s_003-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_001-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_001-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_002-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_002-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_003-ddp.jpg
20110404_M44-f6.9-2x2-000.5s_003-ddp.jpg
20110404_M95-f6.9-2x2-060s.jpg
20110404_M95-f6.9-2x2-060s.jpg
IMG_0593.JPG
IMG_0593.JPG
IMG_0594.JPG
IMG_0594.JPG
IMG_0596.JPG
IMG_0596.JPG
20110411_M44-f10-2x2-000.2s_002-ddp.jpg
20110411_M44-f10-2x2-000.2s_002-ddp.jpg
20110411_M44-f6.9-2x2-000.2s_002-ddp.jpg
20110411_M44-f6.9-2x2-000.2s_002-ddp.jpg
20110411_M44-f10-1x1-000.2s_002-ddp.jpg
20110411_M44-f10-1x1-000.2s_002-ddp.jpg
20110411_M44-f6.9-1x1-000.5s_002-ddp.jpg
20110411_M44-f6.9-1x1-000.5s_002-ddp.jpg
20110424_M57-f7-1x1-24s-test_001-ddp.jpg
20110424_M57-f7-1x1-24s-test_001-ddp.jpg
20110424_M57-f7-2x2-24s-test_001-ddp.jpg
20110424_M57-f7-2x2-24s-test_001-ddp.jpg
20110424_M57-f7-1x1-60s-test_001-ddp.jpg
20110424_M57-f7-1x1-60s-test_001-ddp.jpg
20110424_M57-f7-2x2-60s-test_001-ddp.jpg
20110424_M57-f7-2x2-60s-test_001-ddp.jpg
New lens cell  19-May-2011
New lens cell 19-May-2011
M101 with the new version of the lens cell (19-May-2011).
M101 with the new version of the lens cell (19-May-2011).
M101 - Pinwheel Galaxy  19 & 21-May-2011
M101 - Pinwheel Galaxy 19 & 21-May-2011
M13 - Globular cluster in Hercules
M13 - Globular cluster in Hercules
Moon in Hydrogen alpha
Moon in Hydrogen alpha