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March 30, 2015: Gobsmacked at 0.3Å


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I had a second light for the Solar Spectrum 0.3Å H-alpha filter late this afternoon, after a quick look with the SolarMax-II 60mm, which showed a lot going on on the disk, and a nice spike on the western limb. The reason I couldn't resist having a look with the more cumbersome APM 80mm with ERF and Solar Spectrum filter was the arrival of the Baader TZ-4 tele-centric. The TZ-4 is a good deal lighter than the TV PowerMate 4x, and provides a more rigid connection to the filter. This reduces focuser slop and improves balance. It still needs a variable extension tube to reach focus. Once I did achieve focus, I was gobsmacked at the level of detail I could see, way beyond the result with the 60mm SolarMax at 0.7Å. The detail around AR 12305 and the spike nearby on the limb was astounding, with a real 3D effect. Details within the various filaments were also crisp. I used the WO 7.5-22.5 zoom, and could crank up the magnification to around 120x without problems. I never managed that with the SM-60 (80x is the highest I managed with the SM-60).



Again, I had to cut the observing run short due to encroaching clouds, but I was very pleased to get any time behind the scope. I cannot wait to start imaging with this filter (Friday, perhaps, if the forecast is right).

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Nice one, Michael!

I wonder how much is down to 0.3A versus 0.7A, and how much down to aperture?

I don't find a huge difference in the view between my Quark and Tele Vue 60 versus SolarMax 60. Quark in 85mm scope easily bests the SM60 for detail. Quark in 100 versus SM60 is like Usain Bolt versus me over 100mm :-o

Of course, 60mm or smaller is a handy size and can make sense for full disc imaging or lower power observing. I use my 60mm the most, because of grab and go. But for detail closer in, you cannot beat aperture!

With my Quark and ED100, I usually view at 120x and it normally takes 150x as well. I don't really feel the need for closer than that but I will try 190x next time under good seeing if I remember. I think there are some parallels to lunar observing.

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Cheers Luke. In this case I think it should mainly be due to the narrow bandwidth. I stopped the APM 80mm down to 64mm to keep the focal ratio at F/30. I do not think the four extra millimetres give this extra contrast and detail. The central obstruction of the SM-II etalon might reduce contrast a bit.

I might start experimenting with larger aperture masks to see if the filter works well at e.g. F/26.

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Nice one, Michael.

I'm looking forward to comparing the Quark in my TV76 with the newly acquired TV102. Same quality instruments with the same optical design and bandwidth of the Quark (not taking into account the different focal ratio, which of course makes a difference), should show the differences more aperture provides.

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