ZENITHSTAR 61 II F/5.9 APO DOUBLET
William Optics
Apochromatic doublet
2.2 kg
ZENITHSTAR 61 II F/5.9 APO DOUBLET - Gold / OTA Only is backordered and will ship as soon as it is back in stock.
The William Optics ZenithStar 61 Version II is a two element apochromatic refractor with a focal ratio of f/5.9 and a focal length of 360mm. Utilizing FPL-53 synthetic fluorite glass, this telescope provides excellent aberration correction.
The 2" 10:1 rack & pinion focuser is smooth, stable and reliable, providing no slippage over long imaging sessions. The Z61 Version 2 includes the new CNC-machined and anodized Cat handle bar with finder-style saddle is perfect for attaching a guide scope or other accessories. The ZenithStar 61 II also includes William Optics' innovative clear Bahtinov mask integrated into the lens cap.
For best imaging results, it is recommended to pair the ZenithStar 61 II with its matching Flat61A field flattener or the Flat61R 0.8x reducer.
Note: As the Flat61 an adjustable flattener, you must adjust the distance for your specific telescope. See the Instructions tab above.
Specifications
| Optical design |
Apochromatic doublet |
|
Objective diameter |
61 mm |
|
Focal length |
360 mm |
|
Focal ratio |
f/5.9 |
|
Image circle |
43 mm (with Flat61A field flattener) |
|
Compatible flattener |
William Optics Flat61A, Flat61R |
|
Mount attachment |
210 mm Vixen-style/Arca-Swiss dovetail bar |
|
Focuser |
Rack & pinion dual speed (10:1) 2" diameter |
|
Camera connection |
M54 x 0.75, 2" |
|
Backfocus |
67.9 mm (with flattener/reducer) |
|
Tube weight |
2.2 kg (including accessories) |
|
Tube length |
245 mm (fully retracted), 315 mm (fully extended) |
|
Tube diameter |
75 mm |
|
Dew shield diameter |
80 mm |
|
SKU |
WO-A-Z61IIGD (Gold), WO-A-Z61IIRD (Red) |
Included items
- ZenithStar 61 II
- Lens cap with Bahtinov mask
- CAT finder saddle handle bar
- 210 mm Vixen-style dovetail bar
- M54 to 2" adapter
- 2" to 1.25" adapter
- Soft carry case
Downloads
 ZenithStar 61 II manual
|
Instructions
Note: Once you have unscrewed the rear adapter to the appropriate value in the table below, the remaining backfocus distance to make up will be 55mm from the rear M48 thread.
Distance adjustment needed for correct backfocus
| Zenithstar 61 | 12.9 mm |
|---|---|
| Guidestar 61 | 12.9 mm |
Customer Reviews
I wanted a quality doublet refractor as a grab & go scope light enough with accessories for my EQ modded SW AZGTI mount. The ZS 61 11 fits my requirements to a tee. I also included the matching Flat 61 R 0.8 x reducer and a WO vixen style mounting base for my ASIAIR Pro. The first light image from the scope was a single guided 5 min exposure of the Orion Nebula.taken with a OSC camera & an Optolong L - Extreme filter.
I have no reservation in recommending the scope and Telstar Australian for their excellent customer service.
An excellent all-round scope. I wanted something that could handle astro & wildlife photography, finder scope, guide scope and occasional spotter scope duties and the Z61 fits the bill. But - you really do need the flattener. Without it, the Z61 has a lot of field curvature, particularly for an APSC DSLR or bigger. Without the flattener, my DSLR photos were only sharp from the center to halfway across the photo. Add the flattener and we're sharp to the edge. No chromatic abberation to speak of - even sunlit reflections only show a pure white reflection - much better than the ED72 or ED80. Contrast and sharpness are excellent. Built quality is top notch - everything is smooth and consistent. One mildly annoying design aspect is that the focus knobs don't quite clear the mounting foot - so every time I take it in and out of it's case, I have to release the scope from the ring, turn and replace so it fits back into it's padded bag. (If you're not worried about your focus knobs being parallel to the ground, this won't be an issue). Focus travel is smooth, consistent and generous at around 70mm. Focus with the flat 6A at infinity is around halfway through the travel - so plenty of scope (pun intended) for close-ish photography. While the focus unit does not turn, the flattener does have the ability to spin so you can adjust the camera's angle easily. Also makes for a nice sharp finder scope - although the field curvature does make it's presence felt. I am looking forward to lots of photography through this very nice bit of kit.
better than I thought. Great quality scope and light. Great grab and go scope.
