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Home > Field Flatteners & Reducers > Altair PlanoStar 2" 0.79x 3-Element Reducer

Altair PlanoStar 2" 0.79x 3-Element Reducer

Altair PlanoStar 2" 0.79x 3-Element Reducer
Altair Planostar 0.79x 2" Reducer Spacing Diagram Info for CCD or DSLR cameras
Price: £149.00
Incl. VAT 20% ( £24.83 )
Product code: PLANOS-2-0.79-M48
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This 2" 3-element 0.79x reducer is designed to work with Altair Astro and other refractors with focal ratios from F6 to F8, optimized at F7. 
Best results are with sub-APS size sensors (about 22mm or so), such as those found on CCD cameras, however it is compatible with 35mm full frame format sensors, utilising about 85% of the field whereafter some Vignetting begins to appear - more so than the larger 3.0" version.
We therefore recommend this reducer for scopes with around 100mm or less aperture with sub APS size sensors.
It has a rear M48 thread for connecting your DSLR or CCD camera.  It is possible to get good results with 35mm sensors, however the spacing between CCD sensor and rear lens needs to be correct.
Please see the spacing diagram where distance data for various Altair refractors and Altair M48 DSLR adapters is available, as calculated by our optical engineers.
Because the sensor to lens spacing tolerance of this flattener is about 1mm, you will need to fine-tune the distance to get the optimum results. Various accessories are available to help with this process (see below).
With slightly smaller than APS CCD sensors, performance is very good and Vignetting low, and the smaller the CCD sensor, the less spacing tolerance matters, making the reducer easier to use. Spot size is ideal for cameras with sensors larger than 6 microns. The reducer screws directly into the rear focuser rotator of your Altair EDT APO, converting it into a faster focal ratio 5-element astrograph. An F7 scope becomes an F5.53 astrograph.
This reducer product is designed for use by customers who have some imaging experience, and is not recommended for those taking their first steps into imaging. The 1.0x Planostar flattener is recommended as a first step and is far more spacing-tolerant.

Altair Astro PlanoStar 0.79x Reducer specification:

  • The 2" PlanoStar reducer corrects for field curvature and reduces the focal length of the telescope by 0.8x.
  • 3x FMC lens elements when combined with the front triplet lens system, produce a 5-element optical system with excellent colour correction.
  • High quality multi-coatings on all surfaces ensure maximum transmission and almost zero reflections for good contrast images.
  • The flattener is threaded directly to the Altair 3" large format focuser for optimum rigidity. Simply remove the 2" pushfit adapter and screw the flattener into the rear of the focuser. It also has a 2" Pushfit format barrel to fit most telescopes.
  • an M48 rear thread allows connection to modern imaging systems or your Canon or Nikon DSLR with the appropriate M48 DSLR adapter.
  • The optimum distance from the rear flat shoulder (excluding the m48 thread) of the flattener to the CCD chip in your camera is shown on the diagram. It's possible to fine tune the spacing between your CCD camera or DSLR chip by using the Altair variable and fixed M48 spacers. We recommend buying the Altair M48 spacers as a set to use in various combinations to get the ideal backfocus. If you subtract the light path distance taken up by your camera and accessories from the distances shown in the diagram (see image gallery for enlarged version), you will achieve the ideal spacing for your scope.

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