ZWO FF90 f/6.8 APO REFRACTOR
The ZWO FF90 is an apochromatic quadruplet flat-field astrograph that offers high performance for an exceptionally low price. The quadruplet design makes it perfect for both visual observation and astrophotography. The objective lens features an element of extra-low dispersion glass (ED) that minimizes chromatic aberration.
The ZWO FF90 is a versatile instrument and excels not just at imaging, but as a grab & go visual telescope.
The OTA itself weighs just 3.9kg (4.5kg with tube rings and dovetail bar) and has an overall length of 513mm with the dew shield contracted, making it easy to transport.
Unlike traditional refractors, the quadruplet design does not require a separate field flattener and you do not need to calculate precise backfocus. With a large image circle of 44mm, the ZWO FF90 is a highly capable imaging telescope.
The 3" dual-speed rack & pinion focuser is precise and rigid. It is natively compatible with most motorized focusers on the market including the ZWO EAF. The focuser includes 2" and 1.25" visual adapters as well as M48 and M54 camera adapters. On the rear there is a 360 degree rotator with fine rotation angle markings for precise framing. A 2" mounted filter can be attached to the rear M48 camera adapter.
Unlike most refractors, the FF90 includes two finderscope bases on either side of the focuser, allowing you to attach both a standard guide scope and control unit such as the ASIAIR without the need for additional accessories. The handlebar also includes a finder-style slot, allowing for even more possibilities.
The inner surfaces of the retractable dew shield are covered with matte felt and the interior of the telescope tube has matte paint and internal baffles, to reduce internal reflections and light scattering.
Note: the mount shown in the product images is not included with the telescope.
Specifications
| Optical design |
Apochromatic air-spaced quadruplet with ED glass |
|
Objective diameter |
90 mm |
|
Focal length |
609 mm |
|
Focal ratio |
f/6.8 |
|
Resolving power |
1.63 arc second |
|
Stellar limiting magnitude |
11.96 |
|
Max. magnification |
177.5 x |
|
Light gathering power |
102.88 times the human eye |
|
Mount attachment |
230 mm Vixen-style dovetail with 1/4"-20 & 3/8" screw holes |
|
Focuser |
3" rack & pinion dual speed 1:10 |
|
Tube weight |
3.92 kg (4.52 kg with dovetail and rings) |
|
Tube length |
513 mm (636 mm with dew shield extended and photographic adapters) |
|
Tube diameter |
96 mm |
|
Dew shield diameter |
109 mm |
|
Connections |
2", 1.25", M64 x 0.75, M54 x 0.75, M48 x 0.75 |
|
Focus point (imaging mode) |
75 mm from M48 thread, 93 mm from M54 thread |
|
Focus point (visual mode) |
112 mm from 1.25" adapter, 122 mm from 2" adapter |
|
SKU |
ZWO-FF90-APO |
Items included
- FF90 OTA
- Pair of tube rings
- 230mm Vixen bar
- 2" visual back
- 1.25" eyepiece adapter
- M64 - M54 adapter
- M54 - M54 adapter
- M54 - M48 adapter
- Manual
Downloads
 Instruction manual
|
