GreatAttractor

Everything shot with 90 mm refractor + Lunt 50 etalon. Smoky prominences (~1 h total): M5.3-class flare on 4/02 (0:46 h total): AR 2661 on fast-forward (5 hours with 5-minute intervals), with a minor C2.1-class flare. Solar rotation clearly visible: 7-pane mosaic:

It's a “mod” which increases the aperture (and resolution) at the cost of reduced sweet-spot size (i.e. whole disk cannot be viewed in Hα). Details: https://solarchatforum.com/viewtopic.php?f=9&t=19238

I believe this only applies to an x86 guest on an x86 host. But virtualizing the Pi is an ARM guest on an x86 host.

Good result, Dave. Autostakkert! will handle a drifting image without problems. Regarding the glare - keep a towel (e.g.) on hand and just put it over your head and the box for focusing/etalon tuning. And make sure your next laptop has a matte screen

Good to know. I'm considering moving up from my Chameleon3 ICX445 to one of those fast CMOS sensors. Keep us posted!

The first Chameleon was a USB 2.0 ICX445 camera, but these days there is a whole series of "Chameleon3" cameras: https://eu.ptgrey.com/chameleon3-usb3-vision-cameras from 1.3 to 5.0 MPix (that's why I state my sensor when listing the HW used in capture).

Great images, and the animation is a killer!

Great shots! I was wondering what I'd try to image during a total eclipse, and after seeing this and other images I know now it would be a HDR corona. Do you have enough data to attempt a corona time-lapse? Perhaps some movement close to the disc would be visible over these few minutes.

Yes, a very good demonstration there. It's definitely possible, however, the usable field of view will be smaller than with f/7. The linear size of sweet-spot stays the same (so it covers the same portion of your camera's sensor), but (due to the longer f.l.) the image now has larger scale (i.e. less arc sec/pixel); if at f/7 a solar feature encompassed n pixels, now it's 10/7·n = 1.42·n pix. Aperture stays the same, so the level of details visible is the same (they're just bigger). In effect, it's best to stay as close to f/7 as possible. On the other hand, using a smaller F-number would clip the incoming light cone and reduce the effective aperture.

Excellent details in the animation, including penumbral waves. Let's hope for some spectacular activity next time!

F/7 is recommended. If you couple it with an objective with larger F-number, the linear size of sweet-spot will be smaller (and if you use a Barlow to stretch it to cover your camera's FOV, you'll be likely oversampling). If you use an objective with smaller F-number, the incoming light cone will be clipped (and with it the effective aperture). I use a 90/660 (so f/7.33) achromat in my mod. It is absolutely worthwhile, just keep in mind the trade-offs. Unlike a Lunt 80 etc., a Lunt 50 with larger objective will have a limited sweet-spot; you won't be able to view/image the whole disk at once. For small FOV high-resolution imaging (say, a 1/3" sensor) it's fine.

Yep, you'll need a head cloth to get rid of reflections. BTW, to me the introduction of glossy screens always looked like a fad ("improved clarity and vibrance" and all that). Fortunately, laptop vendors still have matte-screen models and that's always my key requirement when buying a new one.

Oh, come on, most of us here have :> There's plenty on Astrobin (see e.g. http://www.astrobin.com/users/GreatAttractor/collections/131/) and elsewhere. It's just that once you transition to Hα, it's hard to go back. As for your overexposure issues, it could be due to the ND filter being too bright; at the same time, an f/6 refractor gives a very bright image at prime focus. Possible solutions: - use the Baader ND5 film over the objective lens instead of the wedge (very cheap, practically the same image quality) - add a Barlow - add another 1,25" ND filter (like 25% or even darker; they're cheap too) - add a green filter ("visual" or the Baader Solar Continuum); not only reduces brightness, but improves granulation contrast Combinations of the above will also work. Not recommended, as image resolution is proportional to aperture. The only reason for using a mask would be bad seeing (too bad for full 123 mm), and for white light I'd suggest keeping it at at least 80 mm.

Milky haze or not, that's some beautiful activity there!

That's right, Mesa.