Altair Wave Series 125 EDF APO Refractor w Heavy Duty M92 R&P Focuser

Product code: AA125EDF-OTA
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£1,499.00 UK Price
£1,249.17 (ex. VAT) International Price
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Product information

The Altair Wave Series 125mm EDF F7.8 APO is a highly specified doublet APO refractor which offers large aperture and high resolution for the visual observer or imaging enthusiast. The 125EDF becomes an F6.2 Flat Field Astrograph with the optional 0.8x reducer.

Distinctive features of the Altair 125mm ED refractor:
  • Better colour correction than any other ED Doublet in this size / focal range with faster cooldown than a triplet - and a much lighter lens cell.
  • Optical test report, with every lens carefully adjusted to meet Strehl 0.95 minimum in more demanding green light. Tested over the full aperture of 125mm. 
  • Heavy Duty CNC 3" Rack 'n Pinion geared focuser with 2" and 1.25" adapter. Allows direct threaded connection of the larger M92 Planostar reducer and flattener with less vignetting at the field edge.
  • Planostar 0.8x Reducer gives tight spot size over 40mm image circle suitable for astrophotography. The larger format M92 version fits the large focuser for less vignetting and more light at the field edges.
  • Optical tube weighs 8.3kg, well within the range of most mounts.

Why a big doublet refractor? A 5" long focal length ED refractor hits the perfect balance for visual observers, whether you are into planetary, lunar, deep-sky or solar observing. An ED doublet lens cools faster than a triplet lens, because there is no centre-element with an insulating air gap so thermal equilibrium is reached quickly. Frant-end weight is also minimised for a nice balance, and the longer focal ratio allows superb colour correction and memorable planetary views. Finally two lenses means two less air-to-glass surfaces than a triplet for better contrast and less scatter. The 125 EDF is a good choice for high resolution solar imaging. (Please see some solar images). Performance for white light solar observation with the Altair 2" Hershel Wedge gives the ultimate crisp views. The contrast and resolution are high enough to easily see granulation and delicate structures within sunspots. Views and images with the Daystar Quark Hydrogen Alpha, Sodium or Calcium eyepieces are also superb. 

APO performance, modern design: Usually Altair's "APO" designation is reserved for triplet refractors only, however, the 125 EDF, whilst a doublet refractor, has no colour aberration visible in-focus. This is thanks to a long F7.8 focal ratio and a modern computer aided design. An optimisation process simulates lens performance, taking millions of permutations into account and consulting a vast catalogue of optical glass before deriving the radii and spacing of the objective lens. Completed in 2017, the designer's only criteria was to use modern Synthetic Fluorite FPL53 ED (extra low dispersion) glass and to keep the focal ratio at F8 or shorter to allow for an easy-to-manage tube length. Every lens surface has a different radius in this design, something quite uncommon amongst refractors, making the lenses harder to polish, however the results are well worth the effort. Glass melt data has also been used to calculate the lens element spacing.

Dedicated field flattener / reducer for the Altair 125mm ED Doublet APO:
Dedicated PlanoStar 0.8x Reducer/Flattener (RED08-M92-M48-125EDF) fits the M92 focuser. It covers a full frame sensor and allows imaging at F6.24 with 780mm focal length. The reducer comes with an M72 to M48 spacer pre-calculated to give a 55mm sensor to flange distance. However, the spacer can be removed, revealing an M72 female thread on the reducer body, which gives 71.86mm of sensor to flange distance. To use the reducer in this way, you will need an M72 male adaptor to whatever thread you require to connect to your camera, filter wheel, rotator or off-axis guider.

Altair Wave Series optical test report: Your Altair 125mm ED Triplet APO optics are repeatedly tested and re-figured during the final stages of production, until signed off by the optician in charge of the production batch. The best quality ED glass is used element, which is fully annealed and cooled to relieve internal stresses. Each lens cell has a serial number engraved on the front ring. Working closely with our optical technicians, we have introduced a unique multi-tier quality assurance process for all Wave Series lenses, to ensure the highest quality and lowest chromatic aberration. These lenses are modified, and are far superior to the "normal" production quality lenses offered by most manufacturers. Star tests speak for themselves, and colour correction is superb, as can be seen from the various observing reports and images taken with Wave Series refractors. During the production process, a laser interferometer image is acquired in 532nm green light, and imported into fringe analysis software to create an optical test report summary. This test report is included with your telescope (see example image below the main product image). Each image is a "snapshot in time" of the lens on the test bench. Vibration, air currents and other environmental factors can influence the image, and the outcome of the report, though these factors are minimised during testing in a climate controlled environment. Providing a test report is a useful way for us to assure that our our production quality is consistent from batch-to-batch. The report is included with your telescope, which corresponds to the serial number engraved on the lens. Please see example star-test and optical test report images.
Optional Altair 10x60mm deluxe right angle finder scope: An optional Altair Astro 60mm RACI (Right Angled Correct Image) 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 better optical quality. 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 finder scope has a prism diagonal which ensures the image in the finder is the right way up and orientated correctly left-to-right, making objects quicker and easier to find. 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.
What can I expect to see with my Altair 125EDF Refractor telescope?
The Altair Wave Series 125mm 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 you could spend a lifetime watching the sun rise over crater walls, Lava plains, impact craters and mountain ranges. The image is significantly brighter than a 4 or 4.5" refractor due to the larger surface area of the objective lens. In terms of deep-sky objects, the 125 EDF performs very well on the brighter Deepsky Objects. The AA125EDF will easily 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 shows a true "smoke-ring" shape against a dark background. This telescope can be used with nebula and light pollution filters to bring out even more detail. 
Recommended mounts for the Altair 125EDF Refractor: 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. The Altair Sabre AZ Mount is the perfect portable non-electronic mount for the 125 EDF. Motor driven GOTO Mounts capable of carrying this telescope without struggling are the iOptron AZ PRO, iOptron iEQ45, Celestron / Synta CGEM and EQ6, HEQ5. For long exposure deepsky imaging, an iOptron iEQ45, CEM60 or EQ6 are within capacity for the 125 EDF.
125mm EDF specification:

  • Aperture / Focal length: 125mm / 975mm. (780mm with PlanoStar 0.8x reducer).
  • Focal Ratio: F7.8. (F6.24 with PlanoStar 0.8x reducer).
  • Resolution: 0.93 arc seconds.
  • Limiting Visual Magnitude +12.6.
  • Highest Useful Magnification - 246x (atmospheric conditions permitting).
  • Air spaced ED Doublet APO lens with optical test report and interferogram image.
  • Fully multi coated on all optical surfaces for high transmission.
  • New 2022 3.7" Dual speed Rack 'n Pinion focuser with improved bearings, 170mm back-focus and 100mm travel. Full 360 degree rotation with Teflon tipped screws.
  • 2" rear Self-Centring Adapter on focuser.
  • Aluminium tube with white matte powder-coat.
  • Retractable, lockable dew shield.
  • 1:10 ratio micro focuser knob.
  • Optional 60mm Deluxe right angled finder scope with illuminated reticule.
  • CNC machined tube rings compatible with Altair TMS M6x30mm hole spacing. Felt lined.
  • Vixen-format dovetail bar.
  • 1.25-2" adapter with brass compression ring.
  • Scope Weight - 7.9kg without accessories.
  • Scope Length 838mm with dew-shield retracted.
Availability: These optics are modified to achieve a higher quality images. Both the lens element spacing and the centration are set up to get the best balance between colour aberration and the best possible star-test. This process takes time and we regularly reject lenses or combine them in different combinations. It is impossible to predict how long it will take to modify a particular batch of lenses to our standard because each lens is different. Rather than manage a "wait-list", we have a simple "first come first served" policy. Please click on the "notify when in stock" button to receive an automatic email update when this product is ready for ordering. When the notification email has been sent, our system will automatically purge your email address. Please Note: The price and specification are subject to change without notice.

Product Info

Brand Altair
Product Code AA125EDF-OTA
Delivery Weight Package