Vixen 25mm Ortho vs TV Plossl 25mm in H-alpha

[michael.h.f.wilkinson]

Just had first light of a Vixen 25mm Ortho I picked up off ABS-UK. I used to have a 25mm circle T in 0.965" which I liked a lot (unlike the shorter orthos which I seriously hated), but sold it with my old scope. The main reason i snapped up the Vixen orthoscopic was not so much nostalgia, but the fact that the 25mm TV Plossl has a field stop a good deal larger than the 19mm free aperture of the Solar Spectrum filter, which gives a somewhat ragged appearance to the edge of the FOV in the otherwise excellent H-alpha set-up. The 42 deg AFOV of the ortho should cut the problem down, but I did wonder if the quality would be the same. I tested it just now, and the result is that the Vixen Ortho is the perfect match for the Solar Spectrum set-up. As the set-up works at F/25.6, the 25mm gives optimal magnification, and although some slight vignetting can occur even in the ortho, it is a much more pleasing sight. The image quality is essentially the same as the TV Plossl (not too surprising given the slow speed of the system, and the monochromatic nature of the light. Will also try the two on other targets later

[jetstream]

Great info Michael, knowing which EP's have a small fs for this application is very useful, I'm going to watch for one of these. I would love to hear about the Solarspectrum filter, maybe you can do a review in the future? Just one question   how is the contrast for visual? how long does it take to heat...  oops that's 2... thanks Michael

[michael.h.f.wilkinson]

Great info Michael, knowing which EP's have a small fs for this application is very useful, I'm going to watch for one of these. I would love to hear about the Solarspectrum filter, maybe you can do a review in the future? Just one question   how is the contrast for visual? how long does it take to heat...  oops that's 2... thanks Michael

Visually the Solar Spectrum has superb contrast, even though the image is a bit darker than with the SolarMax-II 60mm at the same exit pupil. The Image in the SolarMax tends to look a bit washed out after looking through the Solar Spectrum. It takes about 5-6 minutes to warm up. I will do a full review in the future.

[michael.h.f.wilkinson]

BTW, any other 25mm ortho should work similarly

[Pig]

I haven't viewed the sun through a solar spectrum but it seems Vixen Ortho type eyepieces are very well suited to solar applications. They certainly perform very well with both the Lunt & Quark  Its a pity they don't produce a 32mm SLV

[michael.h.f.wilkinson]

Had some more views in the last few days, and this confirmed the conclusions: excellent EP for solar H-alpha.