Aug24-13, 11:25 AM
And if you can see spots then the defect or dust is near the focal plane of the telescope. Could be an EP but it is more likely the diagonal. If a Mak-Cass is out of collimation it doesn't manifest as spots. I don't even know if a Mak can be easily collimated but I suppose it is possible. All of the surfaces are spherical so factory collimation is pretty robust and the secondary is glued to the corrector so there isn't an adjustment for it.
Check your EP by observing a bright field (uniformly lit daytime image or the moon) and rotate the EP inside the barrel of the diagonal. If the spots move, it's your EP. If not then remove the diagonal and insert the EP directly into the rear of the OTA and see if they are still there. If you still see spots, you might have 'floaters'.
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