Bresser Messier 10" Dobsonian Telescope

A Dobsonian design telescope offers the best value for money in terms of telescope purchase, and the Bresser Messier 10” Dobsonian delivers this and more. A 10” telescope offers an upgrade from an 8” of nearly 50% extra light gathering power, meaning brighter images, better resolution and greater colour saturation. Bigger aperture means better images: see more detail in Saturn’s rings and cloud belts on Jupiter, split globular clusters into individual stars, observe tenuous detail in galaxies and nebulae and see a host of objects that are simply invisible in smaller telescopes.

Bresser’s design philosophy behind the Messier 10" Dobsonian Telescope puts the emphasis on quality core components and upgradability. The main mirror is made of H-PZ33 low expansion glass, in order to minimise cool down time. This primary mirror is ably mounted in a newly-designed cell with 9-point floating supports, which retains collimation well and is very simple to adjust. The secondary spider is thin enough to minimise defraction spikes, but substatial enough to support the secondard mirror assembly well. The telescope has a metal tube, which is strong and offers good stiffness in order to assist collimation retention. The Bresser Hexfocus 2.5” rack and pinion focuser offers class-leading support, due to its hexagonal cross section design, which results in no focusing flex, no matter what orientation the telescope is in the night time sky. This focuser has a heavy duty low profile rack and pinion focuser, which offers similar smoothness to Crayford-style focusers, without the potential for slippage that can occur with friction-based Crayfords at higher altitude under heavy load. Graduated measurements are inscribed on the exterior of the drawtube for precise focus measurement. A dual speed focus control for the Hexfocuser is also available as an additional, simple upgrade. The inclusion of a lockable focuser extension tube for visual use, once removed, enables the user to get to prime focus for astrophotography – a rarity in Dobsonian designs, meaning serious astrophotography is definitely an upgrade possibility.

A good quality 25mm Super Plossl eyepieces is supplied as standard, giving a magnification of 51x. Additional eyepieces of both 1.25” and 2” barrel sizes can be used with this telescope and are available as an added extra, (practical maximum eyepiece focal length is 4.5mm, minimum focal length up to around 30mm).

A 6x30mm finderscope is included, which allows for accurate pointing of the telescope, though this can be upgraded to Bresser's larger and more sophisticated 8x50mm illuminated finder.

The telescope is supported on two large side altitude wheels, which are attached to two adjustable tube rings. These adjustable tube rings allow the instrument to be rebalanced under different accessory loads and also facilitates a straightforward upgrade path to mounting the OTA on a fully computerised equatorial mount at a later date, via a standard Vixen/Synta or Losmandy profile dovetail plate.

The telescope mount is supplied flatpacked and can be disassembled and re-assembled easily for transportation storage.

Newtonian optics with a parabolic primary mirror made from H-PZ33 low expansion glass material

2.5" HEX focuser with rack & pinion drive

Large altitude wheels provide smooth and precise movement, even at high magnifications

6x30 finder and SPL 25mm eyepiece included

9-point flotation system mirror cell for the for primary maximizes optical performance

Tube rings facilitate the use of the optics on equatorial mounts

The parts or the rocker-box are connected with metal furniture fasteners for easy assembly and dissasembly

Diffraction limited optics: Strehl > 0.8

Net weight of Telescope = 11.5 kg

Net weight of Mount = 16.4 kg

Total shipping weight = 36 kg

Features

Diameter Main Mirror: 254 mm

Focal Length: 1270 mm

2.5" HEXAFOC-Focuser

Main mirror made of low expansion glass

Shifiting-free focussing even with heavy acccessories

Tube can be shifted in the rings for easy balancing

Flatpackable rocker box (can be assembled and deassempled for storage)

Altitude bearings are connected to tube rings

Optics usable on other mounts

Adjustment and locking screws have different diameters

What's in the box

Newtonian optical tube assembly

6x30-Finder

25mm SuperPlössl eyepiece (31.7 mm / 1.25")

1 Tube extender 37.5mm for 2.5" Hexafoc

1 Eyepiece holder reducer ring, 2" to 1.25" (50.8 mm to 31.7mm)

2 Tube-rings

2 Side supporting altitude wheels

Rockerbox with two baseplates and side supports (flatpacked for self-assembly)

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.

Are you interested in this product but would like to speak to someone with some more information? Simply fill in the form below and we will get back to you as soon as we can!

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