Askar 91F 91 mm f/6.7 Quadruplet Flatfield Apochromat - with optics test

Name: Askar 91F 91 mm f/6.7 Quadruplet Flatfield Apochromat - with optics test
Brand: Askar Sharpstar
SKU: AS91F
Price: 1099 EUR

The APO refractor provides a flat field of view for astrophotography and sufficient working distance for observation.

91-mm quadruplet apochromat with a focal length of 609 mm (f/6.7)

Integrated flat-field corrector - no additional flattener required

ED glass for high chromatic correction and high-contrast imaging

44-mm image circle compatible with full-frame cameras

Pinpoint stars all the way to the corners of the image

No back-focus calculation required

3" rack-and-pinion focuser with 1:10 fine adjustment

360° rotator with angle scale

M48 and M54 camera mounts included

2" filter thread in the photo extension tube

Retractable dew shield

Multiple finder shoe mounts for accessories

Sturdy 230 mm Vixen-style dovetail bar with 1/4" and 3/8" threads

Tube weight of only 3.92 kg - also ideal as a travel telescope

Including complete optics test by Teleskop-Service on the optical bench (autocollimation) - star image extrafocal, intrafocal and focal as well as Ronchi test and protocol - so you will get a 100% tested telescope.

Manufacturer: Askar Sharpstar

Product number: AS91F

EUR 1.099,00RRP EUR 1.249,00you save 12% (EUR 150,00)

incl. 19 % VAT (DE)

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Askar 91F 91 mm f/6.7 Quadruplet Flatfield Apochromat - with optics test

The APO refractor provides a flat field of view for astrophotography and sufficient working distance for observation.

91-mm quadruplet apochromat with a focal length of 609 mm (f/6.7)

Integrated flat-field corrector - no additional flattener required

ED glass for high chromatic correction and high-contrast imaging

44-mm image circle compatible with full-frame cameras

Pinpoint stars all the way to the corners of the image

No back-focus calculation required

3" rack-and-pinion focuser with 1:10 fine adjustment

360° rotator with angle scale

M48 and M54 camera mounts included

2" filter thread in the photo extension tube

Retractable dew shield

Multiple finder shoe mounts for accessories

Sturdy 230 mm Vixen-style dovetail bar with 1/4" and 3/8" threads

Tube weight of only 3.92 kg - also ideal as a travel telescope

Details..
Technical data..
In the box..
Manufacturer infos..
Safety informations..

Askar 91F - 91 mm f/6.7 Flat-field Quadruplet Apochromat for Astrophotography and Observation

Compact premium astrograph with integrated flat-field corrector

The Askar 91F is a high-quality 91-mm quadruplet apochromat with a focal length of 609 mm and a native focal ratio of f/6.7. Thanks to its integrated flat-field corrector, it produces a perfectly illuminated image field all the way to full-frame - without the need for an additional flattener or complicated back-focus calculations.

The four-element optical system consists of three lens elements in the objective and an integrated corrector element at the rear. High-quality ED glass effectively reduces chromatic aberrations and ensures high-contrast images with point-like stars all the way to the edge of the 44 mm image circle.

Ready to use for astrophotography right out of the box
The Askar 91F was specifically designed to make getting started with astrophotography as easy as possible. Thanks to its built-in flat-field correction, there´s no need to search for the right flattener or to precisely adjust the back focus. Just connect your camera, focus, and start shooting right away.

The package includes a photographic extension tube with an integrated 2" filter thread, as well as adapters for M48×0.75 and M54×0.75, allowing both DSLR cameras and modern astro cameras to be connected without any problems.

Ideal for astrophotography and visual observation
Weighing just 3.92 kg for the tube (4.52 kg including tube rings and dovetail bar), the Askar 91F is easy to transport and makes an excellent travel telescope.

In addition to its excellent performance in astrophotography, it also impresses during visual observation with high-contrast, true-color views of the Moon, planets, star clusters, and deep-sky objects.

High-quality mechanics for precise work
The Askar 91F also meets the highest mechanical standards:

Sturdy 3" rack-and-pinion focuser

Fine focus with a 1:10 reduction ratio

360° camera rotator with scale for precise image alignment

Retractable dew shield for compact transport dimensions

Matte black felt lining for effective stray light suppression

Precision CNC-machined tube in an elegant blue-and-white design

The numerous mounting options are particularly practical. The 130-mm-long carrying handle features an integrated finder shoe mount. Additionally, there are finder shoes on both sides of the focuser, allowing for flexible mounting of finders, guidescopes, or other accessories.

This is how Teleskop-Service guarantees the consistently high quality of the refractor:

The mechanics are tested, and the focuser is optimally adjusted.

The objective lens is inspected for cosmetic defects and cleaned. In addition, all locking screws are checked to ensure they are properly tightened. These often come loose during shipping.

The optics are collimated, and the result is verified on the optical bench. The telescope is assigned a serial number.

A complete optical test report is generated and included with the telescope (star images and a Ronchi test image taken on the optical bench using autocollimation).

Only then are the telescopes transferred to the warehouse and prepared for shipment.

Whether for deep-sky astrophotography, planetary observation, or birdwatching and travel, the 91F is your ideal companion for exploring the world.

Promotion video
The manufacturer has released a video about this telescope:

Aperture:	91 mm
Focal length:	609 mm
Focal ratio:	f/6.7
Optical system:	Quadruplet with ED element
Objective:	Air-spaced triplet objective
Corrector:	Single-element corrector
Coating:	All surfaces are multi-coated
Illuminated and corrected field of view:	44 mm diameter
Focuser:	3" dual-speed rack and pinion focuser
Focuser travel:	30 mm
Connections:	2", 1.25", M64x0.75 female thread, M54x0.75 male thread, M48x0.75 male thread
Visual working distance:	92 to 122 mm from the end of the 2" connector, 82 to 112 mm from the end of the 1.25" connector
Working distances for screw connections:	45 to 75 mm from M48×0.75 external thread, 63 to 93 mm from M54×0.75 external thread
Filter thread:	2" filter thread is included in the M48 camera adapter
Rotation option on the focuser:	Yes, with scale
Dew shield diameter:	109 mm
Tube diameter:	96 mm
Transport length (dew shield retracted):	513 mm (with 1.25" adapter) to 550 mm (with all four photo adapters)
Working length (dew shield extended):	599 mm (with 1.25" adapter) to 636 mm (with all four photo adapters)
Net weight (OTA only):	3.92 kg
Total weight (with tube rings and dovetail bar):	4.52 kg

- 91F Apochromat, OTA
- CNC-machined tube rings with carrying handle and 230 mm long Vixen style dovetail bar
- Set of thread adapters
- Adapter M64 thread to 2" receptacle
- Adapter 2" to 1.25" receptacle
- User manual
- Inspection check list
- Certificate card
- Product warranty
- Cardboard box

Manufacturer / Importeur:	Teleskop-Service Ransburg GmbH
Street:	Von-Myra-Str. 8
ZIP / City:	85599 Parsdorf
Country:	Germany
Telefon number:	+49 89 99228750
Email:	info@teleskop-service.de
Website:	www.teleskop-service.de

Safety informations: PDF Download

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Askar 91F 91 mm f/6.7 Quadruplet Flatfield Apochromat - with optics test

Askar 91F - 91 mm f/6.7 Flat-field Quadruplet Apochromat for Astrophotography and Observation

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