Altair Wave Series 115mm F7 APO Interferometry test report green light

2021 v6 

• Newer more refined OTA design with X-Rings and ultra hard pearl matt powdercoat.
• Large 3.5" CNC Rack 'n Pinion geared focuser with self-centring 2" aperture and 2" to 1.25" adaptor.

The Altair Astro 115mm F7 EDT APO is a highly specified triplet APO refractor which significantly outperforms 4" refractors both in resolution and light grasp, whilst still remaining quite portable.

The Altair 115mm F7 EDT is the ideal multi-purpose telescope platform, suited for the amateur astronomer interested in both visual and imaging use, and offering excellent performance in both areas with perfect colour correction.

This Astronomy Now Magazine review of the Altair Astro 115-805 ED Triplet APO covers the optical performance, although of course the product has evolved considerably since the time of the review in 2011. 
 
Altair Wave Series optical test report: Wave Series optics are repeatedly tested and re-figured at the final stages of production, until signed off by the optician in charge of the production batch. The best quality Japanese glass is used, which is fully annealed and cooled over several days to relieve internal stresses. Each lens cell has a serial number engraved on the front ring. All Wave Series lenses go through a unique quality assurance process, to ensure the highest quality and lowest chromatic aberration. Altair Astro first used this approach in 2010 with the Wave Series telescopes and our optical contractors have a fully bedded-in process. The lenses are first tested on original test-plates to ensure conformance to the correct curvatures, then adjusted in both rotation, centring and spacing. Of course we start off with far superior lenses to the "normal" production quality lenses offered by most manufacturers, using the original test plates. Star tests speak for themselves, and colour aberration is not visible, as can be seen from the various observing reports and images taken with Wave Series refractors over the last 11 or so years. Blue stars show negligible bloat in long exposure images, because the blue channel is particularly well controlled, making this telescope ideal for astrophotography. Astigmatism and Coma are included in the test report output and the test is conducted in green light. Each fringe image is a "snapshot in time" of the lens on the test bench. Air currents and other environmental factors can influence the image and the outcome of the report slightly, but steps are taken to minimise these during testing. 

Optional Altair Planostar 0.8x 3" Reducer Field Flattener converts your Wave Series telescope into a fast F5.6 focal ratio astrograph enabling use of astro cameras. It attaches directly to the M63 thread on the rear of the focuser when the 2" visual back 2" assembly is unscrewed. Spacing setup for the reducer is 55mm.

Here's a typical example setup with Magnetic Filter Holder and the two main models of Altair Hypercam Cameras, being the TEC Cooled or Fan Cooled models. To make things easier, you can choose a complete reducer, filter holder and spacer kit with the following products in the options when ordering:

 
Altair 10x60mm deluxe right angle finder scope: An optional Altair Astro 60mm right angled deluxe finder scope is also available separately, with a machined bracket to fit the 3" focuser, a brightness adjustable red crosshair illuminator, and a wide field eyepiece with helical focuser. A 60mm finder offers significantly more light grasp than a 50mm finder and the optical quality is very high. Blackened lens edges and low reflectance multi-coatings ensure sharp, contrasty images across a very flat field, to help you find fainter objects against the night sky. The image in the finder is the right way up and orientated correctly left-to-right which means the what you see is what you get. Star charts will match up with your view through the finder, making object location much quicker and easier. Furthermore, the right angled design lets you use the finder from a more comfortable position compared to a straight-through finder. It's also now possible to order the Altair 60mm Miniguider which includes our 60mm finder optical tube, rings and bracket and special focuser to connect your webcam/autoguider with 1.25" nosepiece, enabling you to guide your scope with minimal weight increase and maximum portablity using the existing finder mounting point on the telescope focuser. The autoguider/webcam locking focuser is also available to retrofit to the Altair Astro 60mm finder scope if you have one already, or prefer the flexibility of a finder AND autoguider in one unit.
 
What performance improvement does the Wave Series triplet ED lens offer? The Altair 115mm APO sports a triplet air-spaced lens cell for better colour correction than normal doublet or dual lens telescopes. This results in higher contrast, and a cleaner sharper image with less spurious colour. The combination of a triplet ED lens system with high surface accuracy and the fact that this telescope does not have a central obstruction like a reflector telescope, means that it will deliver increased contrast compared to a reflector telescope such as a Schmidt Cassegrain or Newtonian of slightly more aperture, revealing more detail. Because there are more optical surfaces and materials involved, a triplet APO triplet refractor costs more than a comparable ED doublet or "semi-APO" - as well as reflectors of similar aperture. An additional advantage is that you get a wide-field view and a high power view in one package, offering more flexibility than Cassegrain designs.
 
What can I expect to see with this telescope?
The Altair Wave Series 115mm APO will deliver very high contrast images of planets and the Moon. Under steady skies you will easily be able to see detail and changing weather patterns in the cloud belts of Jupiter, the pastel shades of Saturn's planetary disc, as well as the Cassini Division in Saturn's rings. You'll be able to distinguish the changing weather patterns on Mars, as well the dusky surface features and the ice-white polar caps (seasons permitting). Remember planetary viewing is perfectly possible in the city and that light pollution will not affect your view at all. The Moon will reveal so much detail that is isn't worth going into here, suffice to say that you could spend many hours watching the sun rise over crater walls, Lava plains, impact craters and mountain ranges. In terms of deep-sky objects the 115mm 7 performs best on the brighter Messier Objects. under dark skies, it will resolve the individual stars in globular clusters like M13 in Hercules, and you will be able to see wisps of nebulosity in objects like the Orion Nebula giving it a 3D effect, as well as the dust lane in the Andromeda galaxy quite easily. The Ring nebula in Lyra is also presented a nice target and a blue/green colour cast was quite visible. This telescope can be used with nebula and light pollution filters to bring out even more detail.
 
What magnification will eyepieces produce?
As an example, the following common eyepiece focal lengths will give the following magnification:

Q: I need a mount for this telescope, what do you recommend? There are several options available, and we can offer a competitive package to suit your budget, as well as mounting hardware to suit your use scenario. Mounts capable of carrying this telescope without struggling are the iOptron Minitower and Minitower PRO, iOptron iEQ45, Celestron / Synta CGEM and EQ6, or the HEQ5 or larger Vixen GPDX. For imaging, an iOptron iEQ45, Losmandy G11 or EQ6 are fine for this scope.
 
Q: What field flattener and reducer options should I choose for my Altair 115mm ED Triplet APO?

• The 1.0x PlanoStar Field Flattener (PLANOS-3-1.0-M48) is best for smaller objects like galaxies or nebulae or situations where you want to "zoom in" on detail. Note: If you have the older style 3.0" Crayford focuser then you need adapter (PLANOS-3-1.0-M48-RP25-ADAPT) to use the 1.0x flattener with it. 
• On the other hand, if you want a wider field shot of say an extended object, then the PlanoStar 0.79x Reducer/Flattener (PLANOS-3-0.79X-M48) may be a better choice. It's really down to the subject you are framing, just like you would choose the right camera lens to frame a particular subject. The 0.79x reducer/flattener fits all Wave Series focusers without any adapter required.

Altair Wave Series 115mm ED Triplet APO specification:

• Aperture - 115mm F805mm Focal Length
• Resolution - 1.01 arc seconds
• Limiting Visual Magnitude - 11.1
• Highest Useful Magnification - 230x (atmospheric conditions permitting)
• Air spaced ED triplet APO lens with optical test report and interferogram image
• Fully multi coated on all optical surfaces for high transmission
• Aluminium with white stardust paint
• Retractable, lockable dew shield
• CNC 3.7" Dual speed Rack 'n Pinion focuser (360 degree rotation)
• 2" to 1.25" Self-Centering Adapter
• 1:10 ratio micro focuser knob
• Optional 60mm Deluxe right angled finder scope with illuminated reticule
• CNC machined tube rings compatible with Altair TMS M6 hole spacing.
• Losmandy format dovetail plate included
• Hard Case Included
• 2" Adapter with brass compression ring and two clamping screws
• Scope Weight - Approx. 8kg including tube rings, without accessories
• Scope Length 72cm with dewshield retracted, 88cm with dewshield extended