Transmission Coatings (UHTC)

The ETX Maksutov-Cassgrain models (ETX-90, ETX-105, ETX-125) have the option to have transmission coatings called "UHTC" add to the lens surfaces to help brighten the image. When light passes from air to glass, some small percentage of the light will be reflected away. Transmission Coatings are added to the lens surface to prevent this loss of light, so by adding the transmission coatings the optics should provide a brighter view.

Meade produces a standard transmission coating and their UHTC Coatings. "UHTC" stands for Ultra High Transmission Coating. The UHTC coating increase the light between 11-21% over the standard coatings (depending on the frequencies being measured). Technical Specifications for Meade's coatings can be found here. Meade's higher end telescope lines also have UHTC options.

My recommendation is to alway purchase the best transmission coatings possible. The idea of a large aperture telescope is to get the brightest view possible. So anything that increases the lightby 10-20% is good. Firstly, because you will see more with dim targets like nebulae and galaxies, and secondly, if you might later want to sell your scope the resale value would be higher.

Since almost all customers order the higher end transmission coatings these telescopes are usually manufacture that way. If you want standard transmission coatings, usually and depending on the manufacturer, that would be a "special order" and require a few extra weeks waiting because the manufacturer pull the scope off the line to special make it with standard coatings.