Originally posted by audiobomber That would be true if the adapter were perfectly aligned, perfectly planed and precisely the right depth. Unfortunately you don't get that with a $20 adapter. The ones I own have considerable slop when mounted, it is easy to rock the lens assembly back and forth. That does not inspire confidence in the machining.
sounds like a loss of spring tension in the adapter, and it's easily fixed... you can make the lens mount so tight that you can barely screw the lens on.
it's probably the cheap adapters with the cut metal slits you are referring to... put a small screwdriver in the slit, and twist it slightly, opening up the slit... if you leave the lens mounted to the adapter, it probably won't lose tension.
there are a couple of references to lens tests, that claim that a "crooked" adapter lowers resolution... in a perfect lens test, the sensor is exactly parallel with lens, which is exactly parallel with the chart being shot... but when the lens is tilted slightly, it's out of alignment with the chart and the sensor... the focal plane is not parallel.
would anyone claim that the canon t/s 24mm lens loses resolution when it's tilted? probably not... but people are willing to claim that adapter-induced tilt can lower resolution, which is not logical.
---------- Post added 08-15-2014 at 06:17 PM ----------
Originally posted by wildman That's well understood by those of us who use scopes it's called "decollimation"
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Collimation
"Collimation" refers to all the optical elements in an instrument being on their designed optical axis. It also refers to the process of adjusting an optical instrument so that all its elements are on that designed axes (in line and parallel). With regards to a telescope the term refers to the fact that the optical axes of each optical component should all be centered and parallel, so that collimated light emerges from the eyepiece."
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In your case instead of an eyepiece its a sensor.
i don't think that is true.
"The third optical component in the telescope system is the eyepiece. It is a complex magnifying lens used to view the image formed at the focal plane. - See more at:
How to Align Your Newtonian Reflector Telescope
the sensor doesn't do any magnifying at all, it's not part of any optical system.