Aluminum vs. Carbon Fiber
WHICH TUBE SHOULD I CHOOSE: ALUMINUM OR CARBON FIBER?
Stellarvue offers our 102 mm apo triplet in either an aluminum or carbon fiber tube and dew shield. Many prefer the "sexy" appearance of the carbon fiber tube, while others like the classic look of the aluminum tube. We get a number of questions from customers wanting to know which is best. This page will help you decide for yourself by giving you the real pros and cons.
Cool-Down Time: Aluminum tubes adapt to the night air rapidly. Carbon fiber tubes may retain heat, and depending on the size and how they are made, this may present an issue. In the case of the 102, there is actually very little difference. We observed that different carbon fiber tubes retain heat differently. For the 102, we use a relatively thin carbon fiber tube without any interior lining, which permits faster cool-down. Given the success of the 102 tube, we are investigating the use of a specifically-designed carbon fiber tube for larger telescopes. However, we will first continue testing tubes we develop against the same size of aluminum tube.
Durability: Aluminum tubes are powder-coated, while carbon fiber tubes are plastic coated. Tightening the rings too much on a carbon fiber tube can create marks on the tube. Light marks can be buffed out; deep marks cannot. Keep this in mind when deciding on which tube you prefer. Ring marks from over-tightening are not considered a defect, so they are not covered in our warranty. Pay close attention when tightening the rings to prevent leaving marks on your carbon fiber tube.
Aluminum tubes are threaded to accept aluminum fittings. The connections are solid and maintain perfect alignment. Carbon fiber tubes have aluminum fittings bonded to them using epoxy. There have been cases where import telescopes on the market have had issues with parts falling off; much of this is due to improper cementing. For this reason, we bond these parts together ourselves here at our Auburn, CA facility using an epoxy specifically created for bonding aluminum to carbon fiber. Our bonding process increases durability and ensures alignment of parts during the process. So once again, there is no reason for concern with carbon fiber Stellarvue SVX telescopes, as they are bonded here using the proper materials.
Solar Work: Our white aluminum tubes do not get as hot outside in daylight as the graphite-colored carbon fiber tubes, so many customers consider them better when used for solar work. For only occasional solar work, the color of the tube does not present a major issue.
Thermal Expansion/Contraction: Some say they prefer carbon fiber since it does not contract when temperatures drop, which they believe maintains focus better. What they may not realize is that lenses shorten in focal length as they cool down. This does not mean that aluminum is better in this regard; it only means that you should not select carbon fiber thinking you will never need to adjust focus as the telescope cools down. Refocus is required for all telescopes as the temperature drops.
Weight: At 8.8 pounds without rings, the carbon fiber SVX102T-R weighs one pound less than the aluminum SVX102T, which is 9.8 pounds. This is a clearly practical advantage to carbon fiber tubes: they are lighter.
The Bottom Line
You should select the tube type based on your personal preference. Carbon fiber tubes are lighter, but cost a little more. Aluminum tubes may cool down a little faster, although we have sold over 1,000 refractors with carbon fiber tubes and to date no one has complained about thermal issues! Other than these, there are really no practical differences.