How to photograph the sun in UV?

[Doug A]

I've used a telescope and front mounted solar filter to photograph the sun in visible light. For UV do I just add the ZWB1/BG39 stack with the solar filter? 

 

Thanks,

Doug A

[dabateman]

Great question.  My sun filter is just a really dense neutral density filter that sadly I think also blocks UV. I don't know if your would be better. 

I would stack as much Zwb1 glass as you have with even more IR blocking filter to try and control the IR. The sun is a giant IR light emitting source, so I would worry the most about IR leakage. If you bought one or two of those 8mm zwb1 filters,  the sun would be a good subject for them.

[colinbm]

https://www.baader-planetarium.com/en/baader-k-line-filter-1¼"-(double-stacked).html

 

[otoien]

The Baader AstroSolar® Safety Film will remove IR along with other wavelengths according to the OD factor. I recall that Birna reported using the Photographic only version  of the film  with OD 3.8  in combination with a Baader Venus filter when capturing the last transit of Venus in front of the Sun in UV, while for visible light exposures that one becomes too bright without the additional filtering so I am using regular Baader AstroSolar® film with OD. 5.0 for that.

[nfoto]

Øivind recalls correctly for the 2012 Vensus Transit, which I recorded up in Arctic Norway. Even with the Baader U and a midnight sun, the scene got more than bright enough for UV photography.

 

 

Taken with a full-spectrum Panasonic GH-2 and the mighty 1200mm f/11 Nikkor. Astrosolar filter (OD 3.8 for photography)  and the Baader U. This was taken near Tromsø in the early morning hours as Venus was about to exit from the solar disc then not to be seen for > 100 years in a Transit.

 

Although the raw files rendered the UV sun in blue, I found it more appealing to think of the Sun as a golden orange.

[Andy Perrin]

It looks like even that combination gave more solar “surface” detail than white light renditions. 

[Stefano]

Is it possible that since she probably captured the longest UV wavelengths (a blue raw file also suggests that), the lens + filters combonation acted like a weak calcium K-line filter? That would also explain the detail in the photo.

[otoien]

Here is a visual capture from the same event using a generic glass solar filter.

 

And a D40x IR-720nm capture of the same, some channel blowout in the center of the sun.

 

A plain Baader Astrosolar OD 5.0 capture of the sun midday with daylight WB, looking carefully there is some of the same structure (that is not noise), but contrast is very low:

And finally a Baader Astrosolar OD 5.0 capture with daylight WB near sunset, this time with the moon blocking the view during a partial solar eclipse. So this time the color that otherwise is near neutral with just a slight tint has been filtered by the atmosphere to become warmer. As I recall, the sun was pretty low during Birna's Venus transit capture, which could speak for some of the shorter UV wavelengths being filtered out?

 

[nfoto]

The Transit started around midnight. The sun was very low on the horizon, as is the usual manner of the 'Midnight Sun'.

[Doug A]

Spectacular images @nfoto and @otoien. The sun is a fabulous UV subject. Love the sunspot details.

 

Appreciate all the info and tips. I will give this a go at a later date. Needs to be warmer outside.

 

Thanks for sharing,

Doug A

[otoien]

Thanks Doug.

[JMC]

Loving the pictures of the sun in UV. Now, where did I put my UV telescope........

[DKoch]

I'm an avid solar observer; I have a 6 inch refractor with a very narrowband H Alpha filter ( 0.2 A) ...the views are spectacular compared to simple white light views.... the next best thing is usually Calcium K lines . Usually people are imaging with them; hard to see ( and maybe not a great idea to be staring at therewith your naked eye!). But as with all these filters, the narrower the bandwidth ( and the more you pay!) the greater the contrast...

[Doug A]

@DKoch neat setup. Do you also photograph with it?

Thanks,

Doug A