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300mm f/6 MCDK Astrograph v2

The MCDK has been redesigned! We believe this to be the first production telescope with automated collimation and an integrated full aperture guide system. The focuser has been replaced with a motorised secondary mirror, allowing us to replace the previous focuser with a super rigid instrumentation mount point/guiding system. Even the dust covers are automated now. The primary mirror runs on motorised ballscrews and is locked with solenoids. Ideal for remote installations!

The 300mm f/6 has a fully corrected, diffraction limited field large enough for a 35mm sensor (42mm diameter). By fully corrected we mean flat, fully illuminate, free of coma, free of astigmatism and no chromatic abherration for visible and near infrared wavelengths (corrected for 450nm-850nm). Hundreds of hours have gone into the design of this telescope. Truly this is one of the best, if not the best 300mm f/6 astrograph that money can buy.

General Features

Designed and built in Holland, with our own distinctive style. The entire design is computer optimised and every single feature of the telescope from the optical train to the mechanical systems have been through repeated iterations to increase stability and quality while reducing weight and cost without compromising the system integrity. While we have used high tech production methods there has been plenty of good old fashioned human intervention. The materials of the telescope have been carefully selected for their task. In this telescope you will find various exotic alloys of aluminium, steel, stainless steel, brasses as well as various plastics and composites.

Rendering of the 300mm MDDK Astrograph showing the on-board computer and robotic focus/dustcovers
Rear view of the MCDK showing the advanced collimation and guiding system.

Features

  • 300mm f/6 MDDK Astrograph
  • Mirror substrate is Supremax with Aluminium and protective SiO2 layer
  • Lenses are BBAR coated BK7
  • Diffraction limited optical design
  • Spot size < 6 µm
  • Integrated full aperture guide system
  • Optically nulled after construction
  • Optics come with dual certification (internal test and 3rd party confirmation)
  • Automated collimation for primary mirror
  • Automated x/y stage for guide port
  • Automated focusing via secondary mirror
  • Automated dust covers
  • 6061-T6, 6082-T651, 7075-T6 & AlMg5 high grade aluminium alloys
  • SAE 304 & SAE 316 stainless steel alloys
  • PTFE, Acetal and PEEK high grade plastics
  • Losmandy or JTW (taper lock) style dovetail
  • Foam lined carry case
  • Mirror test reports and unique serial number

Optical system

The 300mm MDDK is a modified Dall-Kirkham design, with focal length of 1800mm (f/6) which we feel is just right. It gives the high light collection capabilities typical to a large aperture catadioptic system but without the long focal length and the focal length of a more typical newtonian but with far superior optical performance. The MDDK is telescope that is meant to be trouble free and a high performance telescope that just works. The primary and secondary mirrors are made of Supremax (Schott Germany), while the corrector lenses are high performance BBAR-coated BK7 glass. The following test results are directly from the prototype astrograph, each set of mirrors and lenses are hand figured and will be better or at least equal to this original astrograph prototype. Certification will be provided with each unique astrograph.

  • PV-wavefront error - no larger than 1/15 Lambda across entire surface of mirror
  • Surface RMS error - <10nm
  • Strehl ratio - >0.98
Test images of the Moon, using a 250mm mirror hand figured by the same person responsible for the MDDK optics. Some resolution lost to re-sizing for the web. Please email for full image.
Wire test, foucalt test and PDI test.
Surface profile. Note central bump is an artifact caused by interpolation and is actually where the hole is in the mirror.
Wavefront error in the active area.

Optical Performance

Polychromatic spot diagram. Wavelength range 450nm through to 850nm. Shown on axis and 5, 10, 15 and 20mm off-axis
Spot diagram matrix - wavelength (column) against off-axis distance (row).
Polychromatic point spread function for 450nm to 850nm, on the optical axis.
Polychromatic point spread function for 450nm to 850nm, 20mm off the optical axis.
Vignetting diagram.

Mechanical System

There is little point having some of the best optics money can buy if the rest of the telescope is not also equally exquisite. The whole system has had several hundred hours of computer simulations and design optimisations. Each iteration has been more rigid and lightweight than the last. Performance has taken priority over both cost and ease of manufacture, much to the annoyance of our machinists. As a result we have some features and materials not seen before in other telescopes. While other telescopes are typically made of aluminium and carbon fibre, ours also contains exotic stainless steels as well as high tech plastics and bronzes. This has enabled the reduction in size and weight of many components while gaining rigidity. The deviation of the focal point on the sensor from from horizon to horizon is just a few microns, smaller than all but the largest pixels.

The mirror holders are self centering and will hold collimation for life with the exception of transport or accidental knocks. The primary mirror collimation knobs are custom machined and run on bearings for absolute precision, both the primary and secondary knobs have nice large knurled grips for easy adjustment. Materials are chosen for maximum thermal stability, corrosion resistance and are over engineered just enough to guarantee reliable collimation. The primary mirror holder is a unique design made of stainless steel and has floating mirror support arms with one degree of freedom to completely eliminate deformation due to weight related stresses while retaining absolute precision and rigidity (parent pending). This also allows room for the 6 cooling fans without any additional length to the tube. The primary cooling system is a Di Mauri configuration and the radial spacing of the fans ensures even cooling of the mirror.

The entire system is micro-baffled to eliminate reflections. The baffles are made using custom ground tooling, no quarter is given to convenience over performance. These baffles are made of acetal, a very rigid yet light plastic which is then flocked to reduce reflections to the absolute minimum. The corrector lenses are factory adjusted, but are adjustable and also removable (for spectroscopy). By keeping the length of the telescope to a minimum we also guarantee enough back focus to use a DSLR (or one of our Ultimate deep cooled DSLRs) with a filter wheel. Mounting is via a dovetail.

Customisation

Given our nature of custom projects and the low production volumes of this system, we have decided to offer a full customisation service free of charge. You may opt for any colour of anodising (standard will be orange), hydro dipping (camouflage, carbon, animal skin. You name it, there is a pattern for it!), painting, plating, or any finish you choose. You can even choose the weave pattern of the carbon tube, you may also opt for a different type of dovetail. For such an investment we are willing to go all the way to make you happy. You may also have your name, observatory name or institute laser engraved onto the telescope.

Rendering of the 300mm MDDK Astrograph.

Ordering Information

Due to demand and the amount of time needed to hand figure optics as well as machine components that are on the limits of manufacturability, the lead time for this telescope is 6 months. This includes all aspects of manufacture and is a concrete maximum delivery time. This is the kind of low volume specialist work that we thrive on and we are pulling experience from all our pre-JTW Astronomy professional experience. From petrochemical to motorsport, aviation to agriculture all has had a small hand in this telescopes design. To own one of these ground breaking telescopes do not delay and email us at info@jtwastronomy.com today!

The JTW MDDK 300mm f/6 Astrograph costs 12999,99eur complete