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Wednesday 19th: Overcast but some sunshine is promised.
With most of the vital parts now present I can carefully balance the new 6" H-alpha OTA. [Telescope]
The D-ERF and its cell add 1000g right on the nose of the already heavy objective lens in its own cell. The hefty tailpiece I turned, plus the PST etalon and filter stack, will help to balance the nose-heavy arrangement.
The D-ERF and its cell add 1000g right on the nose of the already heavy objective lens in its own cell. The hefty tailpiece I turned, plus the PST etalon and filter stack, will help to balance the nose-heavy arrangement.
I am still waiting for delivery of the 2" Beloptik KG3 UV/IR filter. Though its slight weight is not going to noticeably alter the balance of the telescope. Nor is it absolutely essential at this time of year. It will earn its keep on long solar sessions when the sun is both "hotter" and higher.
While it is nice to have the 7" refractor available for white light viewing of the sun, moon and planets it is not essential. I keep wondering whether I shouldn't just mount the new 6" for the moment. So I can concentrate on it alone. While I judge its imaging potential and fix any unforeseen foibles. The heavy mounting will hardly notice it is carrying only one instrument.
The new telescope should provide improved views in H-alpha compared with my previous and very secondhand, 6" Celestron. The new iStar H-alpha specific objective lens should be superior in its intended pass band. The native f/10 objective should provide a better match with the PST etalon's needs. It removes the need for the 1.125 GPC.
The new OTA should provide a much cooler instrument. The full aperture D-ERF should considerably reduce internal heating compared to the previous internal D-ERF. The cooler [far more heavily filtered] beam should not thermally impact the PST etalon. They are know to be sensitive to temperature.
Whether a hotter beam affects the air within a solar telescope is a bit of an unknown. Baader claim a cooler OTA when their D-ERF is blocking heat from entering the OTA. Air is transparent and may not know it has a hot or cooler beam passing through it. Usually a target has to directly absorb the sun's focused heat and produce thermal air currents in the internal air.
Whether a hotter beam affects the air within a solar telescope is a bit of an unknown. Baader claim a cooler OTA when their D-ERF is blocking heat from entering the OTA. Air is transparent and may not know it has a hot or cooler beam passing through it. Usually a target has to directly absorb the sun's focused heat and produce thermal air currents in the internal air.
The glass, optical components are largely transparent except when they are blocking filters. It is possible these can warm and produce plumes of agitated air. The air in the closed tube of a refractor is always considered far more stable than a reflector. Not that this limits a refractor to a closed tube design. Truss and skeleton tubes do exist in both commercial, professional and amateur solar refractors.
That's a lot of "shoulds" but why bother to build a new telescope except to improve my solar imagery? Will any improvements be immediately visible on the 25" monitor screen? Even more importantly: In the final images after processing?
The cost of a 6" commercially produced, H-alpha telescope is at least five times higher than my total expenditure so far. These manufacturers have to satisfy the cosmetic and optical expectations of those able to afford over ten thousand pounds for such a specialized instrument.
Fortunately I do not have the pressure of achieving cosmetic perfection. I only demand optical and mechanical excellence. Time will soon tell whether my own expectations were set too high. The sun has just broken through the overcast to light up the dome! Blue skies are here! See Pt.2:
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