From some digging online and based off the little bit of solar photography I have done it looks like the normal solar filters will filter out the prominences.  If they don't, then the brightness difference between the prominence and the sun must be tremendous.  You could try stacking many images to bring them out, but I can't find any evidence of them on my solar filtered photos when I bring the exposure way up.  The "bloom" even from the filtered sun when over-exposed is still overpowering.

I think that the h-alpha is the only way to limit the exposure appropriately to see the prominences plus the details in the surface of the sun.

I am not sure how I would mount one on a super-telephoto lens.  I don't see any that mount on the front lens element.  Maybe something like the energy rejection filter from Thousand Oaks (http://thousandoaksoptical.com/products/h-alpha/) and then a drop in h-alpha filter.  Looks like the drop-in filter would be 52mm for the Nikon f/2.8G 400mm telephoto.  I can't find any 52mm screw in filters, but you could probably take a 2 inch h-alpha filter and mount it on a 52mm uv filter and make it work.

Biggest thing is just getting the energy down.  It wouldn't take much of a mistake to damage/destroy the camera and/or lens.

I'm already working on plans for it. I may take students to it again, but I may set out for the wilderness.

Following up on photographing prominces without an h-a filter, and without an eclipse, here's my attempt.

600mm, 1/30 sec, f/9, ISO 800.  Then applied a reverse radial filter just over the sun's diameter, dropping exposure to -4.  This was my poor-man's attempt at some kind of mask over the sun.  Everything outside the radial filter is "as shot".  Exposure of the overall shot was probably +3EV to +3.5EV; Lightroom's clipping indicator still shows some dynamic range available, so no true blow-out on the original.

Sun 20170909 Filtered by FredMan, on Flickr

I think that even if I used a real mask on the solar film or lens, without the moon blocking out most of the light, prominences are just too faint compared to the rest of the solar output to photograph without using something like an h-a filter.  Too much light and too much atmosphere is just scattering the light to the point where prominences simply can't be seen.  That, or there aren't any prominences right now :)

Here's the entire frame as-shot, except for cropping.  

Sun 20170909 Unfiltered by FredMan, on Flickr

And here's a shot at 1/60 sec, rest the same, cropped and processed for a "normal" white-light sun shot.  All the cool sunspots have either faded or rotated off to the east.

Sun 20170909 by FredMan, on Flickr

Good attempts.

Here is the last SOHO EIT 304 image.



You can see more here
https://sohowww.nascom.nasa.gov/data/realtime/eit_304/512/

There are most likely prominences. They just get overwhelmed without the hydrogen alpha slot filter.

Here is my best picture during totality.  We had a cloud come across right as totality started, and it stuck around for the whole
thing.  I was using a Meade ETX70-AT telescope and using my cellphone to take pictures through the eyepiece.

Attached File

I can't stop staring at this pic. The scale of what's going on is impossible to fathom and it's beautiful.