Hi Shoshana, Indeed silver will give higher reflectivity than aluminum, but it oxidizes quickly and the reflectivity deceases quickly.  Silvered mirrors in some environments need to be re-coated multiple times per year.  Around here it would more likely be annually.  Mike Clemmens silvers the mirror on the 70 inch.  You can check with him for details.  (I hope I spelled his name correctly.) Aluminum that has been overcoated with silicon monoxide is a great alternative.   The reflectivity can approach 92% or 93%.  You will not be able to tell the difference between aluminum and silver.  The overcoated aluminum will also last for many years. The big question is the accuracy of the curve on the mirror.  It is easily tested if you have the right equipment.  Lacking a tester, you want to make sure that stars snap into focus, and that the images are not fuzzy when the scope is focused.  You need a night with good seeing to do this.  Alternatively you can look at terrestrial objects at least five miles away on a still day.  Summer isn't good for this viewing because of heat waves.  You can minimize this by checking the focus early in the morning before the sun rises.   You can also look at the out-of focus disks of a star and make sure that the illumination is uniform.  Make sure that both inside and outside of focus there are no brighter nor darker rings of light. All of this being said, you may not have access to the telescope to perform these tests.  The seller may have certification that the mirror meets at least 11/8 wave accuracy (the Rayleigh criterion).  If not you may not know until you can use the scope on a good night. Hope this helps and doesn't confuse. Brent............................................................................................................................................................................................................. Telescope purchase questions (Truss tube Dob with go to and tracking) Hi everyone! Well, if there are no more stars, I'm retiring, lol. j/k So, I'm in the market (so far at this time) for a go to Truss Tube Dob with tracking. (for the purpose of OBSERVING....not photography) With less experience than you folks, I am asking anyone who can assist me some questions: 1. Mirror quality (what should I look for)....noticed some are 'aluminum coated for brighter images'. Etc...., some have fans, etc. 2. Go to programs. Companies have different software.....synscan....etc. Wondering about reliability also....re: tracking 3. Looking for a collapsible one....so larger sizes ok. Seems like some have a counterweight option and a more minimal base (not like heavy disks as Lightbridge) 4. What company is the most reliable with good customer service? 5. Some of the newer trusses look great but don't seem to have go to. 5. I'll be watching Memorial Day sales, been watching Cloudy Nights..... 6. Not in an extreme rush.....wanting to get good quality at a good price (doesn't everyone?) 7. Will also add a telrad or finder I might be able to carry 70 lbs on my back, lol Thanks for your time and attention:)....again THANK YOU All the best, Shoshana If there is a local rep who can explain features and benefits and compare across vendors, that's an idea also:)