ZENITHSTAR 73 III F/5.9 APO DOUBLET
William Optics
Apochromatic doublet
2.83 kg
ZENITHSTAR 73 III 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 73 Version III is a two element apochromatic refractor with a focal ratio of f/5.9 and a focal length of 430mm. Utilizing FPL-53 synthetic fluorite glass, this telescope provides excellent aberration correction.
The 2.5" 10:1 rack & pinion focuser is smooth, stable and reliable, providing no slippage over long imaging sessions. The new CNC-machined and anodized handle bar with finder-style saddle is perfect for attaching a guide scope or other accessories. The ZenithStar 73 III also includes William Optics' innovative clear Bahtinov mask integrated into the lens cap.
For best imaging results, it is recommended to pair the ZenithStar 73 III with its matching Flat73A field flattener or the Flat73R 0.8x reducer.
Note: As the Flat73 an adjustable flattener, you must adjust the distance for your specific telescope. See the Instructions tab above.
Specifications
| Optical design |
Apochromatic doublet |
|
Objective diameter |
73 mm |
|
Focal length |
430 mm |
|
Focal ratio |
f/5.9 |
|
Image circle |
43 mm (with Flat73A field flattener) |
|
Compatible flattener |
William Optics FLAT73A, FLAT73R |
|
Mount attachment |
210 mm Vixen-style/Arca-Swiss dovetail bar |
|
Focuser |
Rack & pinion dual speed (10:1) 2.5" diameter |
|
Camera connection |
M63 x 1, 2" |
|
Backfocus |
66.2 mm (with flattener/reducer) |
|
Tube weight |
2.83 kg (including accessories) |
|
Tube length |
330 mm (fully retracted), 420 mm (fully extended) |
|
Tube diameter |
TBD |
|
Dew shield diameter |
TBD |
|
SKU |
WO-A-Z73IIIGD (Gold), WO-A-Z73IIIRD (Red) |
Included items
- ZenithStar 73 III
- Lens cap with Bahtinov mask
- Finder saddle handle bar
- 210 mm Vixen-style dovetail bar
- Soft carry case
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 73 |
11.2 mm |
|---|
Customer Reviews
As the title says, the Zenithstar 73 III is my first refractor. I am using this in my first foray into Astrophotography. I spent a lot of time researching my first purchase, and was very impressed with all the reviews I found on the internet. Having a full frame DSLR that will be part of my Astrophotography kit, I wanted a telescope where I could utilise the full sensor. Upon receiving the telescope, I was more that impressed with the build quality and the overall look. I have also purchased that Flat73A filed flattener and this proved extremely easy to install. I had also purchased the ZWO ASI533MC Pro camera, and this is what I fitted first. I have only had one opportunity to use the telescope (clouds and rain), and I must say I am very impressed with my first results. I am looking forward to getting a decent strecth of clear skies so I can use both of my cameras on this telescope.
A great compact fast refractor, easy to set up and small enough to handle large wind gusts without affecting the guiding. Having a light polluted garden, I needed something fast to get detail from a duo band filter and I have not been disappointed. The build and optical quality are excellent, and I have bought many Williams Optics products in the past. As yet I have not got a field flattener as the camera I am using, an ASI 294MC is not full frame and I can get round any problems with the Lens module in StarTools 1.8.
The telescope was despatched within 24 hours and arrived quickly.
After deciding to get into Astrophotography or EAA to be more precise. Having never looked through a telescope prior, I had no idea as to what I was after. I started watching as many videos and reading as many reviews and as I could find on the subject. One name that kept coming up was William Optics, in particular the Z73. It seems about the perfect focal length for those beautiful Nebula shots you see all over the internet and once mated to the Flat73 reducer/flattener it will only get better. Although I have only been doing this for approximately a month; I know I made the right decision. The build quality is second to none and the images it can produce are nothing less than stunning. I only hope I can learn to use it to its full potential. (I have yet to attach the flattener as I'm waiting for the M48 T-ring)
