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GTF 81 - 5 Element APO Refractor Telescope - Limited Edition [GTF81]
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About the William Optics GTF 81 - 5 Element APO Refractor Telescope - Limited Edition...
The stunning new William Optics GTF 81APO is the new jewel of the apochromatic refractor world. From the pristine white finish on the CNC to the elegant red beauty which has more than just good looks... New GTF 81 features total 5-element in 2 groups design by using high-quality FPL-53 extra-low dispersion glass that reduces any secondary spectrum to an unbelievable degree,the second group of ED element (flat field corrector) is correcting the edge of flatness to the best quality (cover up to 40mm of image circle).
William Optics GTF 81 - 5 Element APO Refractor Telescope - Limited Edition Features...
Five element in two groups air-spaced objective (FPL-53) in adjustable CNC machined ultra high precision lens cell.
Excellent color correction.
Each lens is Fully Multi-Coated with a special super-high transmission coating (STM Coating) on all surfaces.
This F/5.9 lens is ideal for astrophotography.
The Digital Display Gauge - DDG - allows you to take precise focusing readings down to two decimals precision instantly.
Extra-smooth 360 deg. rotatable 2.5" Rack & Pinion focuser with 1:10 dual speed: a treat to use during astrophotography. No image shifting!
Comes with two locking screws on angled positions for heavy load applications.
Large aluminum knob with installed thermometer and aluminum protection cover.
2" & 1.25" adapter included in the price.
Anti-marring brass compression rings.
Carry handle with V-shape night glowing illuminator.
Guiding scopes are optional.
90mm mounting rings are optional.
Though you will never need it, you have a 2-year warranty from WO, and the certainty that we will be there to assist you even beyond that, if you need!
William Optics GTF 81 - 5 Element APO Refractor Telescope - Limited Edition Specifications...
Optical Design : Apochromatic Refractor Telescope
Focal Ratio: F/5.9
Focal Length: 478 mm
Objective Type: Five element with FPL-53 Air Spaced (2 groups), Fully Multi-Coated, STM coatings
Resolving Power: 1.43 seconds of arc
Limiting Magnitude: 12.2
Lens Shade: Retractable
DDG Focuser: 2" 360 Rotating Camera-angle Adjuster, 1:10 fine focus Focuser Travel Length: 3.15" (80mm)
1.25" Adapter: 2" Brass Compression Rings
Field Stops: knife edge Baffles
Tube Diameter: 90mm
Tube Length: 440mm Fully Retracted - 484mm Fully Extended
Tube Weight: 3.7 k
William Optics Product Number: GTF81
About The Image...
Author: George Ionas
Mount: NEQ6 PRO GOTO
CCD Camera: Starlight Express QHY9, 8.3M pixels, 5.4uM pixels square
Scope: William Optics Gran Turismo GT-81 f/5.9 APO Triplet working at f/4.7 (FL=380mm)
Filters: Astronomik 12nm Narrow Band Filters (Ha,OIII,SII) Camera
Temperature: -35 Degrees C below ambient
Exposure: 6x600s with each filter
Field Size: 160 x 120 arc min
Comments: No Dark frames or Bias frames were used
Location: New Zealand