: 1)How does the baffle work and how can I decide the position of baffle? Baffles work by blocking light that is coming into the tube from some other angle than what you want it to. The light hits the baffle and reflects back out of the tube (hopefully!). : 2)I am going to cut 2.2m tube in 3 pieces, first piece with ... Don't bother with the second piece. The way it is often done is with 4 rods connecting you first and third pieces in a truss fashion. Make the 4 tubes very accuratly and you can do a wood clamp around them at the top and bottom and sue the tube length to put the upper assembly in the same place each time. : 3)What is the merit to induce 2" focuser compared with smaller focuser? Bigger views and wider views!!! Low power eyspieces (above 32mm) don't work well in the smaller formats. I would make 2 secondaries that I have indexed to the secondary holder for camera and small eyepiece work and another larger secondary for lowpower work. : 4)As for secondary mirror size, which is better to choose a mirror which is a little bit larger than the ideal size or a little bit smaller than the ideal size to observe planets. Observing is better with the smaller mirror as contrast starts to suffer with larger secondary mirrors(Assumed from question). : 5)Merits and demerits of curved spiders. No spikes but larger thickness of these tends to lower the contrast more. The thicker the obstruction, the greater the loss of contrast. Hope I have answered you well.

• Speaking of Spiders - Tony Dunlap - May 28, 1998 - 15:21 UTC