Quote:
Originally Posted by Legin
However this brings a few problems. One it is extremely dark and I can hardly see anything and secondly when I loosen the center screw (the one you need a screwdriver for) the whole mirror seems very loose.
|
Shine a light on the subject?
If the mechanism is like the GSOs, the three collimating screws play an important role in supporting the secondary mirror firmly in place. If you adjust the central screw such that the mirror moves away from the three collimating screws, yes it will get "floppy". You need to screw the three collimating screws in to meet the mirror holder again. The opposite - if you have to adjust the central screw to move the secondary away from the primary, you'll need to back off the three collimating screws so the secondary can move in that direction. Reach in and hold the secondary holder and adjust central screw until it is well located under the focusser, then screw the collimating screws back to meet the mirror. Then check secondary position again and adjust. Keep iterating smaller and smaller moves each time. After that, away you go adjusting the tilt of the secondary.
Another thought is that there should be a firm spring around the secondary central screw pushing the miror holder away from the spider. Is it missing? Is it really too weak? Replace it with something the right length that is firmer. Bunnings have a selection of springs - it's the compression springs you want.
Quote:
Originally Posted by Legin
Oh and what about barlowing my laser? Will this help. I have heard this helps a fair bit. Heck it will probably cost me a few bucks for a barlow lens but it is worth it if I obtain avery accurate collimation tool.
|
Well a barlow is a useful device to have, anyway. The GSO 2" 2x ED is quite economical and will be useful with your eyepieces to obtain a greater range of magnification (and a few other benefits, but let's not start an argument about eye relief here!).
With respect to a barlowed laser for collimation, my understanding is that the physics of the barlow lens removes a key error inherent in using the laser. I just pop my regular laser in a barlow (either the 2x one above or even a Televue 3x) after I think everything is well lined up (after regular laser and cheshire), then I have a piece of white card through which I have punched a regular hole punch hole. I reach the card into the tube between the focusser and the secondary and allow the laser to pass through the hole. Invariably, the shadow of the ring on the primary is smack bang centred on the laser beam.
A bit of a fancy approach, but here is an article that will help you with the concept of a barlowed laser. (Note Scott has a laser with barlow built in).
http://www.iceinspace.com.au/index.p...63,406,0,0,1,0