About this product
Part Number: A-Z73IIGD
New 2019 model
The NEW William Optics 2019 Zenithstar 73 APO features an air-spaced doublet lens with fully multi-coated optics and an Ohara FPL-53 ED glass element for sharp, high contrast images virtually free of false-colour.
Provides high resolution images when used for astrophotography or wildlife photography and is a convenient ultra-portable telescope for visual astronomy (think binocular astronomy targets).
It's fast f/5.9 focal ratio and compact size makes it ideal for convenient wide field astrophotography or piggybacking.
Supplied with mounting ringsb and Vixen-style dovetail bar.
CNC machined aluminium for a superior fit and finish.
Dual speed 2.5" 1:10 R&P focuser.
Available in Blue or Gold anodised.
Ohara FPL-53 vs FPL-51 ED Glass
The dispersion properties of ED and SD glass elements are important in determining the overall colour correction. The abbe index is used to quantify the 'partial dispersion' of a particular glass. Pure Fluorite offers the highest partial dispersion at around 94.99 V, Ohara FPL-53 glass is very close to Fluorite at 94.93 V and is often referred to as Synthetic Fluorite. FPL-53 is also noticeably better than Ohara's lower spec' FPL-51 glass which offers an abbe index of 81.54 V.
Field of View Simulator
What's in the box
- Telescope OTA
- Innovative Bahtinov Mask
- Mounting Rings
- Vixen-Style Dovetail
|Focal Length||430 mm|
|Imaging Circle||43 mm|
|Objective Type||ED Doublet, Air Spaced,|
Fully Multi-Coated, SMC coating.
|Tube Diameter||93mm (3.66")|
|Tube Length||390 mm Fully Retracted|
|Tube Weight||2.83 kg|
|Average Rating (1 Review): |
Monday, 24 June 2019 | Francis
I purchased this from FLO earlier this year to go with my Star Adventurer mount (also FLO) and a Manfrotto photo tripod. Initially I thought it was going to be too heavy especially with a Nikon DSLR (APS) mounted but the mount chugged along nicely. The optics on the ZS 73 APO are really nice just managing to the corners on my D5100 but falling off with the FX chipped 800E. I then purchased it's Flat 73A adjustable flattener (not FLO) and the difference in field flatness was very marked even with the FX sensor. The flattener is x1 so no changes in FoV to contend with. I have been taking mono photos with the D5100 up to about 3 mins which is about the best I can get from the Star Adventurer. It's a great visual scope too. Paired with my ES 68° and 82° eyepieces the views are better than I ever expected. I took the ZS-73 up to the Lake District under some better skies than I usually deal with - what a treat.
Please fill in the form below to ask a question.