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Celestron Nexstar 90 SLT Telescope

Celestron Nexstar 90 SLT Telescope
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Price:  £495.00(Inc. 20% VAT)

Model:  22087
Brand:  Celestron
Design  Maksutov
Size  3.5" (90mm)
Computerized  Computerized GOTO
Level  Intermediate
Mount Type  Alt Az

Availability  

  

No stock, please contact us for an ETA



2 Year Warranty On All New Items
(Excluding Batteries & Globes)


  (1 Review)

Affordable entry to mid level computerized GOTO telescope

Designed to be an affordable entry level to mid-level computerized GoTo telescope, the NexStar SLT refractors, reflectors, and Maks are available in the most popular sizes and are loaded with valuable design features. With preassembled, adjustable stainless steel tripods, and quick release fork arms and tubes, NexStar SLT telescopes can be set up in a matter of minutes – with no tools required! You can see details of the lunar surface, Venus and its phases, polar caps on Mars, Jupiter and its four moons, Saturn with its rings plainly visible and much more! Most NexStar SLT’s can also be used as a land-based spotting telescope.

Intelligent Design
Powered by 8 AA (user supplied) batteries or an optional AC adapter (#18778) these NexStar GoTo’s love to travel. The internal battery compartment provides power to the high precision servo motors for rigid low-vibration performance while eliminating cord wrap issues associated with external battery packs.

With the NexStar’s ergonomically designed hand control, the user is free to remove the hand control from its holder for remote use or leave it cradled for hands-free operation. With a touch of a button you can select the object catalog, change the slew speed, view fascinating information about an object, or simply know if a desired object is visible in the sky.

Celestron’s Revolutionary SkyAlign
Using Celestron’s patented SkyAlign (patent pending), simply input the date, time and location into the hand control then slew the telescope to any three bright celestial objects in the sky. You do not need to know the names of the stars – you can even pick the Moon or bright planets!

General Features

• High quality 90mm Maksutov-Cassegrain
• Fully computerized Altazimuth mount
• StarPointer finderscope to help with alignment and accurately locating objects
• Quick-release fork arm mount, optical tube and accessory tray for quick no tool set up
• Sturdy stainless steel tripod and accessory tray included
• Good for terrestrial and celestial observing
• Includes CD-ROM "The Sky" Astronomy Software which provides education about the sky and printable sky maps

Computerized Mount Features

• Proven NexStar computer control technology
• Database allows telescope to locate over 4,000 celestial objects
• SkyAlign allows you to align on any three bright celestial objects, making for a fast and easy alignment process
• Flash upgradeable hand control software and motor control units for downloading product updates over the Internet
• Internal battery compartment to prevent cord wrap during use
• Auxiliary port for additional accessories such as GPS accessory
• Includes NSOL telescope control software for basic control of your telescope via computer (with optional RS-232 cable)
• Compatible with optional NexRemote telescope control software, for advanced control of your telescope via computer

Specifications:

Optical Design : Maksutov-Cassegrain
Weight : 12 lb (5.44 kg)
Aperture : 90 mm (3.54 in)
Focal Length : 1250 mm (49.21 in)
Focal Ratio : 13.89
Finderscope : StarPointer
Mount : Motorized Altazimuth
Eyepiece 1 : 25 mm (0.98 in)
Magnification 1 : 50 x
Eyepiece 2 : 9 mm (0.35 in)
Magnification 2 : 139 x
Star Diagonal : 1.25
Accessory Tray : No Tool, Quick release
Tripod : Steel
CD ROM : The Sky Level 1 and NexStar Observers List (v2.6.4c)
Highest Useful Magnification : 213 x
Limiting Stellar Magnitude : 12.3
Resolution (Rayleigh) : 1.55 arcsec
Resolution (Dawes) : 1.29 arcsec
Light Gathering Power : 165 x
Angular Field of View : 1 °
Linear Field of View (@1000 yds) : 53 ft (16.15 m)
Optical Coatings : Fully-Coated Computer
Hand Control : Fully Computerized / Flash Upgradeable
Slew Speeds : Nine slew speeds: 4°/sec, 2°/sec, 1°/sec, .5°/sec, 32x, 16x, 8x, 4x, 2x
Tracking Rates : Sidereal, Solar and Lunar
Tracking Modes : Alt-Az, EQ North and EQ South
Alignment Procedures : SkyAlign, Auto 2-Star Align, 1-Star Align, 2-Star Align, Solar System Align
Database : 4,000 Object Database
GPS : Optional CN-16 GPS Accessory

Please note that stock levels do fluctuate so please call or email to check today's stock before placing your order.

Average Rating (1 Review):  
Write a Review and share your opinions!

Rating:  
Nexstar 90
05 February 2014  | 

We bought the Nexstar 90 SLT telescope for my father in law. He's been after one for a long time. The telescope is small and light, so it was perfect for him, as he has a permanent back injury. He can carry it and set it up without any heavy loads or bending.

He's used the telescope every time there's a clear night, so we are really pleased we've managed to find one that meets all his needs.

Was this helpful to you?  Yes  /  No

18 of 19 people found this review helpful.

Some items that are showing as in stock are in stock at our holding warehouses, not at the shop. To double check the stock levels at the shop, please contact us on 01909774369 or sales@rothervalleyoptics.co.uk.

The delivery times for most items is 1 - 2 days but again, please double check stock levels on important orders before placing an order via the website.

The delivery costs for courier next day are for mainland UK only. If you live in the Scottish Highlands/Islands, Channel Islands or Northern Ireland, then a shipping surchage will apply. please contact us for prices. Smaller items can still go 1st class via Royal Mail.

Please note that if you are wanting to take advantage of our Saturday and Sunday timed services or next day pre 12 or pre 10:30 services, you MUST check that the stock is here at the shop before placing orders. Also, orders using the Saturday and Sunday services must be placed before 1pm the previous working day. Also, please remember to check that the stock is here at the shop before placing orders. If the stock is not at the shop, we won't be able to ship on any of the timed services. 

Please note International customers will need to contact us for a shipping price prior to ordering via the website. We don't ship all items internationally. It is at our discretion what we ship outside of the UK. This all depends on the size and weight of the items. Please get in touch with us for any postage costs. Please note we do NOT ship telescopes or heavy items outside of the UK. This is due to massive postage costs and problems regarding returns.

If you have any questions regarding stock levels or delivery, please get in touch.

Zygo Interferometer Testing For ED Refractor Telescopes!

We are extremely pleased to announce our Zygo Interferometer is now installed and ready for use! Our experienced staff can test refractor lenses up to 120mm aperture and provide a comprehensive 2 page report showing the optical quality and Strehl ratio, plus much more information. We are using the very latest Zygo MX software to provide a more detailed report compared to other standard reports.

 

The interferometer is essentially a measuring instrument. Within the interferometer is a calibrated laser that is pointed through the optical test surface, then onto a high quality reference sphere, then back through the test subject then to an internal camera which gives us the measurement on the screen. From this, we can adjust the position of the test optic and the reference sphere to obtain a perfectly calibrated system. The more central the laser to the test optic and then on return, the better and more accurate reading and measurement we can take. This takes a lot of adjustment to get the best results from the optical surface. Once the measurement has been taken, we are provided with a series of results that show the optical quality of the surface plus other information. Continue reading for an explanation of the individual values and you can also see a test report that was done on one of our RVO Horizon 60 OTAs. 

We are offering certain telescopes with a Zygo test at an extra cost. Mainly ED doublets and triplets. All available telescopes with a Zygo test report are listed here. Just select Zygo Test Report from the drop down box at the top of the listing and we will test the optics in house and provide a full 2 page report with your scope. This will show you the optical quality of your telescope optics. We can also offer this service on your refractor telescope. Please get in touch for more details about this. 

At Rother Valley Optics, one thing we pride ourselves on is customer service and quality of our equipment. When we test your telescope, we will ensure that it is of the highest quality otherwise, we will reject the scope under our strict quality control and test another model for your peace of mind. One of the main values to look at when testing a refractor is the Strehl ratio. The higher this number, the higher quality lens you have. At Rother Valley Optics, we will guarantee the highest possible Strehl ratio for your telescope.  We will aim to provide 0.95 Strehl or higher on Takahashi, RVO Horizon, William Optics and many more! Generally, the higher the Strehl ratio, the lower the Astigmatism and Coma meaning a better image quality from your instrument. 

Other measurements such as the PV and RMS are important too. With these measurements, the lower the number the better as it shows less curvature on the lens. The flatter an optical lens, the better it will perform. The PV rating (Peak To Valley) is a measurement from the highest point (Peak) to the lowest point (Valley). From this we get the RMS (Root, Mean, Square). This is a similar figure to the PV and measured exactly the same way. The RMS is basically an average height difference from the PV so again, the lower the better. As you can see form the example below, we measured an RMS of just 0.027 wave which is a very good value.

We also measure the Power with our systems which is essentially the error from the reference sphere to the test optic. The reference sphere we use on our system is a very high quality sphere so the closer to zero the Power, the less error between the 2 elements thus ensuring a higher quality optical surface. 

You will also see some more values such as Astigmatism and Coma. Again, these are measured by the interferometer when we take measurements of the optical surface after adjustment. These are values which ideally would be at 0 but as our test optics are all curved lenses, there will always be astigmatism and coma present. The lower the number, the less of these aberations you will effectively see but with most refractors, you can buy field flatteners which will compensate for the coma anyway. The astigmatisms value is explaining the error between the symmetrical curvature of the lens. Basically, no lens will be perfectly symmetrical, the lower the astigmatism, the more symmetrical the lens surface is. 

Once the Zygo test report has been completed, the optical alignment is thoroughly tested and tuned to ensure they are spot on before they leave us. 

All available telescopes are on the website at the link below and ones we've tested already that are available straight away are also listed.

https://www.rothervalleyoptics.co.uk/zygo-tested-refractors.html

Here is an example of the test what we provide. This was a test on one of our Horizon 60 ED OTA's.

For any questions about this amazing new service, please either call 01909774369 or email sales@rothervalleyoptics.co.uk.

 


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