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PST focus
The pentaprism focus design is one of the weaknesses of the PST, it's only glued to the adjusting bar and can move out of position both in the X and Y axis. This gives astigmatism....
Also note on the later models ( blue objectives) that the extension piece below the eyepiece attachment will contain an additional UV-IR filter element. This is in addition to the BF5 blocking filter in the eyepiece section.
I've also found that the recent PST's appear to be "flooded" with Loctite on all the threaded joints ie gold tube to etalon, etalon to body and the eyepiece spacers etc. This makes it almost impossible to strip them for modification to a 80mm ERF arrangement without damage.... ( maybe Meade have caught up with me and figured using the PST etalon to build a great 80mm Ha solar telescope is to competative to their expensive models!!!)
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