Meade SN6AT SN8AT and SN10AT LXD75 Schmidt Newtonians

Since Meade reintroduced the SNT design with the SN-6AT, SN8-AT, and SN-10AT after a long hiatus as the LXD55 series, they have managed to improve the LXD GEM mount so that it is generally reliable electronically and mechanically. That does not mean LXD75 is optimum for a Schmidt Newtonian. The problem is not so much weight, at least not with the 6-inch and 8-inch SNTs, but length. Schmidt Newtonians necessarily have longer tubes than SCTs of the same aperture: 27-inches for the 6-inch SNT (13 pounds) and 30-inches for the 8-inch SNT (24 pounds). The longer tubes put more strain on the medium-weight LXD75 GEM and make it shakier than it is with an SCT OTA, if still usable. The 10-inch SNT increases both tube length (36-inches) and weight (30 pounds). What was bearable on the 6 and the 8 is just too much with the 10-inch in my opinion.

Optically, the SNT OTAs are similar, differing only in aperture and focal ratio. The 8-inch (Plate 27) and 10-inch are f/4s, and the 6-inch is an f/5. Although the mount these telescopes are shipped with is questionable, the optics are impressive. At a star party under the dark skies of Chiefland, Florida, an informal shootout was arranged between the 10-inch SNT and a 10-inch Dobsonian Newtonian (with a known "good" mirror). The results? The edge of the field in the SNT looked better, with the stars looking like stars instead of comets. DSOs seemed slightly brighter in the SNT, probably due to the LXD75's UHTC coatings.

The LXD75 SNT's features, in addition to UHTC (which is standard), include an 8 x 50 mm finder scope and a single 26-mm Plossl of good quality. The OTA sports a steel tube that is finished an attractive white. All three Schmidt Newtonians include 2-inch rack-and-pinion focusers. This focuser is workable for visual use, but if imaging is to be attempted, it should be replaced with a better unit. Luckily, several companies, including Jim's Mobile, offer vastly superior Crayford focusers that are near plug-and-play replacements for the SNT focuser.

How good are these SNTs? They are more than capable of producing quality images visually and photographically, but there are a couple of things the CAT

Plate 27. (LXD75 8-inch SNT)

Meade's wide field Schmidt Newtonian OTA on a go-to GEM mount, the LXD75 8-inch SNT. Credit: Image courtesy of Meade Instruments Corporation.

Polar Alignment Scope Meade Lxd75

shopper should know. First is that to deliver good images an SNT must be accurately collimated. The process of lining up the optical elements of a Schmidt Newtonian is decidedly more complicated than it is on a Schmidt Cassegrain. The SCT owner only needs to adjust the secondary mirror's tilt. The SNT may potentially require the secondary's rotation as well as tilt to be adjusted. The SNT primary must also be collimated, unlike the SCT primary. Users familiar with Newtonian alignment will be right at home, but SCT users may be in for some head scratching.

The bottom line on the SNTs also depends on their use. Dark skies that encourage wide-field viewing allow these OTAs to perform in world-class fashion, outdoing much more expensive telescopes. Lunar and planetary observers who frequently use high powers may be less enchanted by these short focal length OTAs and their undersize mounts. But, the Meade Schmidt Newtonian design is good. It provides a lot of potential for a little money ($1,000 for the 6-inch, $1,200 for the 8-inch, and $1,400 for the 10-inch). It would be ideal if the three were available in OTA-only configurations. On a sufficiently sturdy mount, these SNTs can really rock.

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