Quote:
Originally Posted by kinetic
Trev,
I think you are missing the point re: spring pressure on a mirror cell.
Sure the GSOs etc have got it wrong with the springs.
But all that is needed is a spring that holds the mirror firm at the setting
of the collimation adjustment. A very firm spring.
Any typical four stroke valve spring does the job.
Zero movement due to mirror weight.
I don't know what eyepiece and focuser have to do with any of that?
Surely that is an issue of what you intend the telescope to do...planetary
(barlows, EP) or deep sky ( focal reducers etc) , each requiring a
completely different focuser range.
regards,
Steve B.
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Hi Steve,
Don't know about you but I have always setup the mirror cells in my telescopes so that the springs are close to being fully compressed.
Well, almost always the three springs will require different amounts of compression, so I try to have the spring under the most compression close to being fully compressed. I have had success with this methodology over the years. It seems to provide consistency of movement.
If using springs of a heavier gauge than the originals, that still provide a similar amount of overall travel, then such springs will be longer when fully compressed.
That is why you need to know at what point of the focuser's travel, focus is achieved for whatever eyepieces, cameras whatever will be used in said focuser.
If the heavier springs result in the primary moving farther up the tube when collimated, then obviously there will be ramifications relating to the amount of travel that will be required of the focuser, to focus whatever equipment that is normally used in it.
Whether or not the use of heavier springs my require the use of a spacer to move out to the point where focus will now be achieved due to the use of heavier gauge, hence intrinsically longer springs.
There is no point whatsoever in ending up with a truly bonza mirror cell that maintains collimation perfectly if none of your equipment can be brought to focus, due to the point of focus moving outside the range of travel of the focuser.
Hope that clears up my point.
Regards
Trevor