Exploring the Sun: Amateur Solar Imaging Techniques

[davenn]

Hi everyone

This thread is for showing your images of solar activity taken with YOUR cameras, telescopes etc.
That is, don't post images from SDO, SOHO or any other professional sources unless you specifically want to ask "how do they do that and what are those solar features I can see?

This is intended for those of you out there, like myself that get out there and do your own imaging and are looking for ways to improve your techniques and general discussion of ideas or just to share your images.

There won't always be times when there is anything worth imaging on the sun. For me, there often can be many weeks between images. But it will be interesting to follow the Sun as it reaches solar minimum and then see the spot count rise as the next maximum approaches.

I will start of by reposting some recent images I had in other spread out threads. It will be good to have them all under one banner

cheers
Dave

 

[davenn]

9 July 2017

AR2665 ... largest spot group for some time
Canon 6D, 800mm, f11, 125th, ISO100 ( the 800mm is a 100-400mm L lens with a x2 teleconverter)
With my eyesight going downhill, I have really been struggling of late to be able to get sharp manual focus

Dave

 

[davenn]

22 August 2017

there are currently 2 significant spot groups visible traversing the face of the solar disk

The centre-left string is active region 2671 and the region near the right edge ( eastern limb) is
active region 2672. AR2672 will continue to rotate across the disk across the next 2 weeks.

800mm, f9, 200th sec, ISO200 and Orion solar filter

Dave

 

[davenn]

2 September 2017

A quick shot of the sun this morning
Nth lower left, East limb lower right

400mm telephoto = x2 teleconverter, 500th sec, f11

Dave

 

[davenn]

4 September 2017

The large group continues across the sun
there has been new spots appear to the east of this long string of spots plus a new set coming around the east limb

400mm telephoto = x2 teleconverter, 500th sec, f11
rotation is from lower right to upper left ( as seen through my camera)
You can also see the smaller single spot up from the large spot chain has also evolved into a much more complex structure over the last 24 - 48 hrs

Dave

 

[davenn]

5 September 2017
The Sun

400mm telephoto = x2 teleconverter, 500th sec, f11
rotation is from upper right to lower left ( as seen through my camera)

The upper group continues to grow in size and complexity and it is also becoming more active

Dave

 

[davenn]

6 September 2017

2 large spot groups continue to dominate the solar disk

Dave

 

[davenn]

16 September 2017

a single spot group is currently visible
but I did capture some bright faculae near the limb in the upper right of the image

This is with my new solar filter film from Baader

Dave

 

[davenn]

This is the new filter film I am using ...

http://www.ozscopes.com.au/baader-astrosolar-safety-film-large-100cm-x-50cm.html

I have been concerned about the focus quality of the Orion filter which is a surface deposited film on a glass carrier
( similar process aluminiumising of glass for making reflector telescopes).
My concerns are centred around having the additional layer of glass in front of the camera lens system and how it
is affecting the quality of the light passing through it.

I purchased this larger sheet, it will be enough to make a number of filters for different camera lenses and for the telescope
It's going to be interesting to see if there are any significant differences between the glass filter and the film filter

cheers
Dave

 

[davenn]

18 September 2017

Still just a single spot group is currently visible
plus some bright faculae near the limb in the upper right of the image

Dave

 

[Stavros Kiri]

Thanks Dave for the great photos (and the thread). With an interesting solar activity it's good to have some real first-hand photos!

Other than being kind of a 'cell phone "maniac" ' , I am not too much into photography myself, but I will be doing my observations and perhaps confirm them here occasionally with your (and other people's) photos.

From your older threads, there is also:
https://www.physicsforums.com/threads/a-little-solar-activity-this-week.829420/

(I particularly like that photo + you mention there how disappointing that solar maximum has been ... [acting weird now that we're heading towards minimum])

Here is a diagram study of the solar cycle:
https://www.spaceweatherlive.com/en/solar-activity/solar-cycle
(shows the Solar Cycle progression ...)

 

[davenn]

Thanks Dave for the great photos (and the thread). With an interesting solar activity it's good to have some real first-hand photos!

cheers

just hope we can encourage any of our resident astrophotographers to add to the threadD

 

[Stavros Kiri]

just hope we can encourage any of our resident astrophotographers to add to the thread

I hope so too. May be you can post the link in the two recent threads for the eclipse (eclipse ... + eclipse photos threads). There were quite a few ambitious astrophotographers there. If we like the eclipse (hidden sun) we ought to like the full sun too ...

 

[NFuller]

I took this one about a year ago. Not too much happening here but I think the image came out well.

 

[Andy Resnick]

cheers

just hope we can encourage any of our resident astrophotographers to add to the threadD

What is this so-called 'sun' of which you speak? :)

 

[davenn]

What is this so-called 'sun' of which you speak? :)

Hey Andy

I assume from that comment, you have been getting a lot of cloudy days

was hoping you would pop into the thread. Not sure of you do any solar imaging ? sunspots etc
If you do, please add to thread so we can keep a good running view of the sun and its activity as time goes byDave

 

[davenn]

I took this one about a year ago. Not too much happening here but I think the image came out well.

good shot, thanks for sharing and I hope to see more

what solar scope/filter system are you using ?
Dave

 

[Andy Resnick]

Hey Andy

I assume from that comment, you have been getting a lot of cloudy days

was hoping you would pop into the thread. Not sure of you do any solar imaging ? sunspots etc
If you do, please add to thread so we can keep a good running view of the su8n and its activity as time goes byDave

I do intend to contribute! Good idea on the thread. I have some excess spectral filters lying around I want to try out- the set of times I am available and the set of times the sun is available has so far been disjoint.

 

[NFuller]

good shot, thanks for sharing and I hope to see more

what solar scope/filter system are you using ?
Dave

Thanks!

The scope is a Takahashi 90mm with a Coronado Ha filter. The image was taken with an ASI120. The image was created using lucky imaging and wavelet filtering.

 

[Drakkith]

Dang, I wish I had the filters necessary to do some solar imaging. Perhaps one day...
Great images by the way!

 

[gmax137]

This looks like a fun sport. Any good links on how to get started, what camera/lens/filter/etc is needed? What kind of exposure times are used for these shots? Can you just use a tripod or is tracking required? Thanks

 

[Stavros Kiri]

What is this so-called 'sun' of which you speak? :)

It's a star! ... I only see one everyday (daytime) ! ...

 

[NFuller]

This looks like a fun sport. Any good links on how to get started, what camera/lens/filter/etc is needed? What kind of exposure times are used for these shots? Can you just use a tripod or is tracking required? Thanks

I started by just googling solar imaging. There are a lot of recipes for imaging and one isn't necessarily better than the other, its more a matter of taste.

Here are some general guidelines:
-Use a white-light filter (cheap and can see sunspots) or a Ha filter (expensive but shows solar flares and sunspots in excellent detail)
-Use a good quality telescope (A large aperture will give better resolution but larger filters are harder to find and more expensive, the best compromise is probably a nice 3" refactor)
-Use very short exposures (the Sun is obviously very bright so it doesn't take much time to collect enough light to expose the image)
-Tracking is less important (Since the exposure time is so short, tracking is not an issue; any tripod will do)
-Take lots of images (Since the exposures are quick, you can take a lot of them and use software to select the best images to stack together. This is called "lucky imaging" and is pretty standard for solar system imaging)

 

[1oldman2]

Dang, I wish I had the filters necessary to do some solar imaging. Perhaps one day...
Great images by the way!

Dave's link in #9 looks like a winner.

 

[jim mcnamara]

@NFuller - could you expand a bit on 'lucky imaging' ? I'm guessing you are processing multiple images into one, i.e., photoshop, and trying increase color contrast?

 

[davenn]

Any good links on how to get started, what camera/lens/filter/etc is needed? What kind of exposure times are used for these shots?

hi there

have a look at the first few images in the thread, I comment in filters and camera settings

you don't need a telescope, just a camera and a decent telephoto lens, preferably 400mm
and up, else the image captured is pretty small. I use a 400mm and a 2x converter on a full frame Canon 6D camera which gives 800mm.
A 400mm on a crop sensor camera will give around 600 - 700mm, depending on the crop factor of your camera

I also intend to add info on more specialist systems like the Coronado solar scope designed for solar viewing/imaging only

Can you just use a tripod or is tracking required? Thanks

just a tripod, there isn't any need for tracking as the shot exposures are all fast ~ 1/500 sec or moreDave

 

[gmax137]

Thanks Dave & NFuller!

 

[NFuller]

@NFuller - could you expand a bit on 'lucky imaging' ? I'm guessing you are processing multiple images into one, i.e., photoshop, and trying increase color contrast?

Lucky imaging is basically a cleaver way of overcoming the normal seeing limits of the atmosphere. Turbulence in the atmosphere will cause the image to wobble and distort. Every so often however, the air is very still and an image captured during this brief time will have excellent resolution. If we take a large number of successive images (basically a movie) some of those frames will be very sharp. This movie can be fed into specialized software (I use FireCapture) which will automatically pick out the best frames to stack into a final image.

 

[davenn]

If we take a large number of successive images (basically a movie) some of those frames will be very sharp. This movie can be fed into specialized software (I use FireCapture) which will automatically pick out the best frames to stack into a final image.

another very popular program for stacking video frames is Registax

http://www.softpedia.com/get/Multimedia/Graphic/Graphic-Others/RegiStax.shtml

this does wonders for planetary imaging using a webcam or other video cameraDave

 

[Stavros Kiri]

For the current solar activity, and to know what to expect to see and photograph, see also https://www.physicsforums.com/threa...ther-update-thread.923468/page-3#post-5845584 and forth ...

 

[davenn]

The Sun today 22 Sept 2017

Some of the bushfire smoke has dissipated tho the sky is still a little murky ... no clouds just not a clear blue ... today's temp heading for mid 30's C

AR 2680 has gone from the lower left limb and AR2681 ( upper right) is making it's way well onto the solar face

Dave

 

[davenn]

after several days of crappy skies ... bushfire smoke as well as cloud. The sky was clear enough today for a quick sun image

AR 2681 has moved further onto the disk and new AR2682 has come around the east limb
The new AR2682 is the returning AR2673cheers
Dave

 

[davenn]

got another image in the afternoon a little better specially after some processing
The seeing was quite poor as can be seen by the non-sharp (ripply) edge of the sun

Dave

 

[Andy Resnick]

got another image in the afternoon a little better specially after some processing
The seeing was quite poor as can be seen by the non-sharp (ripply) edge of the sun

I tried some solar imaging this weekend, using a few 'random' color filters (in addition to an ND3 = 0.1% transmission):

1) BG3 glass (https://www.pgo-online.com/intl/curves/optical_glassfilters/BG3_BG4.html)
2) RG645 glass (https://www.newport.com/p/FSQ-RG645)
3) a 436/10 bandpass filter (band pass is 436 +/- 5 nm)
4) some UV bandpass filters: a 380/40 and 365/20

I realize the bandpass range of these filters far exceeds 'typical' solar filters, but this is what I have. I couldn't tell at the time, but none of the images came out very well- the exposure guide was apparently totally useless and all 3 images were overexposed in their particular channel (R,G, or B). The UV filters didn't work out at all, I guess the Bayer filter and whatever else is put on the sensor cuts off below 400nm or so. That said, it felt like 90°C at the time (it was 'only' 90°F) and I wanted to get out of the direct sun ASAP.

There was spectral bleed-through: for example, the RG645 image has blue and green components that are properly exposed.

One potentially interesting 'feature' is that the sunspot contrast was highly variable- there appeared to be no sunspot when using the 436/10 filter. I'll probably try filters 1-3 again, if for no other reason than to generate separate RGB images.

 

[Andy Resnick]

Better images today- here's an image taken with the BG3 filter:

equipment details: the lens is a 400/2.8 with a 2x teleconverter. I replaced the 'standard' UV blocking filter with a reflective ND4 (20-stop) filter and added secondary color filters as needed; the BG3 and RG645 color filters got stacked behind the ND4, while the smaller bandpass filters I use for fluorescence microscopy got taped to the front of the 2x tele.

Focusing and exposing was a little tricky: tough to use 'live view' because the display brightness can't compete with ambient lighting. The in-camera meter would typically be around EV -3 or more (possibly EV -7), but then the appropriate color channel would not be saturated. Gain was set to "low 1.0' (approximately ISO 50, IIRC), the lens stopped down to f/4 (f/8 w/ tele) to reduce flare, and shutter speed was about 1/200s.

Minimal post-processing: I manually set the off-RGB channels to zero, and set 'gamma' equal to 1.3 or so to improve the tonal range. Images cropped and downsized about 50% or so. The jpg artifacts appeared during downsizing and again after uploading to photobucket- the full-sized images don't look as 'blocky'.

Here's the RG645 image:

and the narrowband (I mis-stated the spec: 465/10nm filter.

Unfortunately, no real differences between the images...