I have a Goldenretreiver, hes about 5 years old and is the best retreiver i've ever had.
Of course there isThe focal point will drift twice as fastWhich means you have to refocus twice as oftenFor a telescope from Walmart that does not focus properly to begin with it does not matterFor a quality instrument it doesBut for such an instrument one would not use either material And you don't want your telescope light, anywayYou want it heavy to reduce vibrations It all boils down to one thing: there ain't no such thing as a convenient, cheap and powerful telescopeYou might get two out of three, if you are lucky.
The Celestron Nexstar 4se is in fact neitherIt is what is called a catadioptric - a compound telescope using both mirrors and lensesSpecifically a Maksutov-CassegrainIt is at the core MORE of a reflector than a refractorThe mirrors do the main work of collecting the light and bringing it to a focusThe lens at the front of the telescope corrects shortcomings in the simple (spherioid) shape of the primary mirror.
The thermal coefficient should not be a great concern in a telescope, as long as the focusing mechanism can compensate for the change in telescope length in the range of temperatures expected for its use, and as long as the telescope is given time to adjust to the ambient temperature before it's usedYou would not want your telescope to be warmer or colder than surrounding air anyhow, because of concerns relating to condensation or air turbulence.
For visual observations, I doubt there is any difference worth worrying about other than the weightI've worked as a welder and I can tell you from first hand experience that aluminum is about half as heavy as steel is, but plenty strong and stiff enough for a telescope tubeThere's the added benefit of being more corrosion resistant and completely rust proofFor photography, the focus will shift as the tube expands or contracts, so you will have to focus your camera to suit the ambient temperature and that will apply regardless of what metal the tube is made fromAn alternative material that makes very light, stiff and thermally stable tubes for telescopes is carbon fiber.
Labs are the best, I think Red labs are the most appealing visually, Newfoundlands are fine retrievers alsoSurprisingly poodles are originally retrievers, their coarse coats helped them in cold water and the ridiculous haircuts of today's show poodles are actually exaggerated styles of the cuts which were designed to give most insulation to necessary areas, head, limb joints, etcI personally would never have one but apparently they make some of the best retrievers, which makes me wonder if awell trained Labradoodle may be THE best retrieving breed ever.
