Focuser compatibility for direct-threaded attachment:
- Fits standard 3" Crayford Focuser on the pre 2014 Altair Wave Series refractors with special adapter (PLANOS-3.1.0-M48-RP25-ADAPT).
- Fits standard 3" Crayford Focuser on the Starwave 80, 102 and 110mm ED Doublet refractors without adapter.
- Fits the new 2014 2.5" Rack 'n Pinion focuser on the 2014 Altair Wave Series refractors without adapter.
The reducer/flattener is compatible with 35mm full frame format sensors, utilising about 95% of the field whereafter minimal Vignetting begins to appear - this is much less so than smaller flatteners due to the oversized lens group.
We therefore recommend this reducer for scopes with 100mm or more aperture, with APS size or larger sensors, however it will happily perform on 80mm scopes too, with sensors smaller than APS.
The spacing between CCD sensor and rear lens needs to be correct to within 1mm or less for large sensors. Up to 2mm is acceptable for smaller sensors.
The PLANOS-3-0.79X-M48 has a rear M48 thread for connecting your DSLR or CCD camera, which further reduces Vignetting due to the larger aperture than older T2-thread (M42) designs.
Please see the spacing diagram where distance data for various Altair refractors and Altair M48 DSLR adapters is available, as calculated by our optical engineer.
Because the optimum sensor to lens spacing tolerance of this flattener is around 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). The more accurate the spacing, the better the performance.
With APS or smaller CCD sensors, the spacing tolerance decreases and so the reducer is easier to use. Spot size is ideal for cameras with sensors larger than 6 microns. The reducer screws directly into the rear focuser of your Altair refractor, converting it into a faster focal ratio 5-element 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 3" 0.79x Reducer specification:
- The 3" 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.