My version of "PST" 
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PSTm (  Solar Personal Telescope - modified)

Although the PST is an excellent solar telescope, (having in attention the relation price/quality)
for  H-Alpha observation, in special for  proeminences, with a little more expense
(and a little ATM work ) it can be much better used.
The following images, are clear, but I must relate that the substitution of the original objective
by another one, cannot (nor must) be made of light spirit.
It is indispensable to not only guarantee the continuity of the integrity of the filter, as also the security in the visual observation. Of the done analysis to the original objective, I concluded that this only leaves to pass cold light and only the visible band in the H-Alpha zone.
Exactly without having been able to confirm, I believe that also the UV must be blocked.
So that these conditions if keep, one will have installing in the place of the objective, two filters:
a : - Filter cut-of  UV/IR.
b : - Filter H-Alpha pass-band of 50 nm (or less).
It is also basic to have in account the relation F/D of the original objective:  F = 10   (40/400).
Small variations for a "higher F" (F=10,5 .... F = 11) do not degrade  the quality of the image.
Variations for a "smal F" than F=10 are not advisable and must be prevented.
Thus, two versions had been home made:
a - 70 / 700 mm  with a normal acromatic lens .
b - 115 / 1200 mm (F = ~10,5)  my " Solaris 1" refractor.
The  exchange from "a"  to "b"  becomes in few minutes, good as well as the replacement
of original objective, in order that it is always possible to make use of the PST in the origin version .
I must still relate that  my version does not transform a PST into a SolarMax.
It remains, as it is obvious, to be an equipment particularly useful for the proeminences and other phenomenons that occur in the solar limb, and one did not observe in white light.
But the exchange of the original objective by another  of bigger aperture and focal distance, is expressed on sensible improvement in terms of resolution of details, thus allowing a good better exploitation of the filters of the PST.
Any questions, e-mail  : alcaria.rego@sapo.pt


Theoretical project





The optical alignment of the set, is guaranteed by two rings in Nylon, with inside dimensions of to the pipe of the PST, and ofside dimensions to the inside of the external OTA. The frontal ring  is entire and the back ring is tottaly cut (after ended) on a  side and on the opposite side it is half-cut  to be able to be introduced without needing to remove the objective (it has a hinge efect).Tres screws in Nylon (or Teflon) placed at the 120 degrees, guarantee the setting of the PST, good as well as the position of the pipe and the security.
Note: the tres rings shown in the image belongs to the 115/1200 mm version.


Provisory key (maybe definitive) to disassemble the objective.The main part, is on inox steel of 1 mm made. The support to maneuver the key, is in brass plate of 0.5 mm, folded and fixed with screws and rivets.









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