The original post on this site was a short description of the Meade Infinity 102mm AZ refractor with a few pros and cons. This rewrite uses Meade’s Infinity 80/90/102 instruction manual and Meade’s Latin American distributor page to give verified specifications and a simple guide to getting started.
Note: Meade’s Latin American site says Meade Instruments has closed operations and product availability is limited, so check support options before buying a used or remaining unit.
Verified specifications
From Meade’s Infinity manual and the Meade Latin America product page:
- Objective lens diameter: 102 mm (4.0 inches)
- Focal length: 600 mm; focal ratio f/5.9
- Mount: alt-azimuth with slow-motion controls on both axes and a pan handle
- Tripod: stainless steel with accessory tray
- Eyepieces: three 1.25-inch Modified Achromatic eyepieces, MA26mm, MA9mm and MA6.3mm
- Barlow: 2x
- Diagonal: 90° erect-image diagonal prism
- Finder: red-dot viewfinder (CR2032 battery)
- Bonus software: AutoStar Suite Astronomer Edition on DVD, with more than 10,000 objects (Windows PC only)
Magnification with the supplied eyepieces
Meade’s manual gives the formula: telescope focal length divided by eyepiece focal length. Meade’s distributor page lists:
- MA26mm: 23x; with Barlow 46x
- MA9mm: 67x; with Barlow 134x
- MA6.3mm: 95x; with Barlow 190x
The Infinity 102 is the largest refractor in the Infinity series. Meade’s distributor says its 102 mm lens collects 28% more light than the 90 mm model and 189% more than the 60 mm model, which means brighter views.
How much magnification is too much?
The manual warns that the most common beginner mistake is using too much power, and that a smaller, bright, well-resolved image is better than a larger, dim, fuzzy one. Orion’s AstroView 90 manual gives a useful rule of thumb: the maximum useful magnification is about 2x per millimetre of aperture. For a 102 mm lens that is about 204x, so 190x with the Barlow and 6.3 mm eyepiece is close to the limit and will only work on steady nights. Meade’s own manual says powers above 400x should be used only in the steadiest conditions, but that figure is far beyond what a 102 mm telescope can support.
The image is right way round
The manual says the supplied erect-image diagonal prism gives a view that is right side up and correct left to right. That makes the Infinity 102 handy for daytime use, such as birds on a distant hillside, as well as astronomy.
Setting up
The manual’s steps, simplified:
- Tripod: spread the legs on a solid surface and set the height with the leg lock thumbscrews.
- Accessory tray: place it over the centre attachment point and rotate until it snaps onto the leg braces.
- Slow-motion cables: attach both flexible cables to the mount and tighten their thumbscrews.
- Optical tube: line up the dovetail rail with the mount and tighten the attachment knob.
- Finder, diagonal and eyepiece: slide the red-dot viewfinder bracket into its dovetail, insert the diagonal prism into the focuser, then the MA26mm eyepiece.
- Align the finder by day: centre a distant object such as a telephone pole in the eyepiece, then turn the finder’s alignment screws until the red dot sits on it. Check again at night on the Moon or a bright star.
Moving the telescope
Loosen the horizontal lock knob to swing side to side, and use the pan handle for up and down; the manual notes there is no vertical lock. Once you find an object, re-tighten the horizontal lock and use the slow-motion controls to follow it as the Earth’s rotation carries it across the view.
First targets from the manual
- The Moon: best as a crescent, when shadows show craters, rays and the dark maria. The manual suggests a neutral density “moon filter”.
- Venus: shows crescent phases but no surface detail.
- Jupiter: bands across its face and its four Galilean moons, which change position every night.
- Saturn: the manual calls its rings probably the most memorable sight; you may see the dark gap in the rings (the Cassini Division, which the manual calls the “Cassini band”).
- Deep sky: the Andromeda Galaxy as a small fuzzy cloud, and the Orion Nebula in winter.
Observing tips
- Start with the 26 mm eyepiece and switch to higher power only for details.
- Let the telescope reach outdoor temperature, and never observe through a window.
- Objects high in the sky look sharper than those near the horizon.
- Use a red flashlight to protect your night vision; the manual suggests about ten minutes for your eyes to adjust.
Care and safety
Meade advises avoiding cleaning the lenses unless necessary: a little dust does not harm the image. Remove dust with a soft brush or ear syringe. Never look at or near the Sun, and children should always have adult supervision.
Quick summary
- 102 mm, 600 mm, f/5.9 refractor on an alt-az mount with slow-motion controls.
- Three eyepieces plus a 2x Barlow give 23x to 190x.
- Erect-image diagonal makes it good for land viewing too.