18 replies to this topic

[bujin9]

Hi all...
question on white light observing and imaging, using my 130mm refractor, my only goal (in regards to this question) is to view and image sunspots and granulation. I have a Thousand Oaks filter for the front end that I used for the eclipse over the summer. Any suggestions regarding being able to see and image granulation? Additional filters from Altair or Baader? A different white light filter for the front end? I currently use an asi 678mc but will probably pick up an asi432mm for solar.
thanks,
Joe

[hyiger]

I have better luck with imaging granulation when the Sun is low(ish) on the horizon. I also use a Baader continuum filter and a Hershel wedge with a circular polarizer but a front end filter (Thousand Oaks) works just as well. 

[ch-viladrich]

I would change the Thousand Oaks filer for an Astrosolar ND 3.8 film. A solar wedge would be even better (in terms of contrast).

Also, a green filter would help (such as a trichomic green filter using in RGB imaging).

It is way better to use a BW sensor.

[igorrr]

Here are my granulation and sunspot images with 152mm refractor, Baader wedge, SC filter, Saturn-M camera. I have not seen any pictures of the same detail posted for the last couple of months. It may need some time to load these pictures in full resolution.

https://astronomy.ru...em.php?id=19598

https://astronomy.ru...em.php?id=19604

https://astronomy.ru...em.php?id=19609

https://astronomy.ru...em.php?id=19639

https://astronomy.ru...em.php?id=19568

https://astronomy.ru...em.php?id=19577

https://astronomy.ru...em.php?id=19582

https://astronomy.ru...em.php?id=19585

https://astronomy.ru...em.php?id=19593

https://astronomy.ru...em.php?id=19596

https://astronomy.ru...em.php?id=19594

Edited by igorrr, 30 November 2024 - 05:35 PM.

[bujin9]

If using a solar wedge (say like something from Lunt or Baader), would I also need to use a front end film like the Astrosolar?....or just an ERF on top of the scope? I've never used a solar wedge before. 

[gstrumol]

No. You either have a front filter or a wedge (plus some additional filtering) , but not both.

 

A typical wedge has a built-in ND3 filter, making the wedge effectively an ND4.35. A standard Baader solar film filter for the front is an ND5, although as Christian noted, you could also get a film that is ND3.8. Combining a wedge with a film filter would make the image very, very dark.

[hornjs]

The equipment aside, how is your local seeing?  If my seeing is not above average or better I am not seeing granulation no matter what equipment I have set up.  

I have a feeling with the jet stream and Montana winter, I may not be seeing granulation for a while.  

I have a 6" Celestron refractor with an Altair wedge and a continuum filter and when the seeing is good the granulation really pops.  

[bujin9]

Ok..great info. My seeing probably isn't the best (as it can be hit or miss when doing planetary imaging). If I catch it before noon, I can get it before it starts to go over my home (assuming the house thermals will add more turbulence to the mix). All my experience has been in deep sky so solar seems to be a totally different animal and I'm just starting that journey. I'm assuming not to waste my time using the C11?

[Sebastian_Sajaroff]

It was very difficult to see granulation on my old 6" F/8 Dobson and Baader film, I suspect thermals inside the tube killed the resolution.
On the other hand, granulation is evident on my 70 mm F/6 refractor with a Lunt 1.25" wedge and a Baader Continuum (green) 7.5 nm filter and using the zoom eyepiece between 15 and 21 mm

Edited by Sebastian_Sajaroff, 30 November 2024 - 07:37 PM.

[Sebastian_Sajaroff]

In my area (Quebec, right under jet stream), time of the day makes a major difference.
The view is much steadier from 1.5 hours after sunrise to 1 hour before solar noon. After that, it’s a lost cause, the image boils.

[gstrumol]

I guess it depends on what you mean by granulation. Here is an image from Christian's excellent book Solar Astronomy, which shows the different levels of granulation, depending on the scope's aperture:

 

(click to enlarge)

 

To really see the cells you'd need a scope around 150mm aperture.

[Spectrum222]

Great shots Igorr!

 

WOW. Yes - 152mm really does a solar shot great!

 

I love mine too, when doing visual. I assume that SC = Solar continuum, correct? (540nm w/~7.5nm FWHM) ?

 

Bujin9,

 

I have to second the folks here's comments re: Solar wedges. That is THE best way for your refractor to get really consistently good images, and as a few others mention, the Baader AS 3.8 solar film full aperture is a second best choice. For visual with that, you will need to employ an additional ND filter to keep brightness levels at or near ND5. So a ND1.8 is very good here. It is a 6%T filter, or you can use a ND0.9 with polarizer to same effect. 

 

IMO, the wedges offer more flexibility for fine tuning the image brightness and contrast, both for visual and photography. 

 

You can also employ additional filtering (such as the 540nm Continuum, or a Baader SWAN C2 (passes Mg-b lines - I have been experimenting with this one recently with my 152mm scope on visual, until we got hit with major winter weather which has all but frozen us here in NW Canada!). There are additional filtering options also, but those are good. 

 

As to which wedges are best, well there are many available, I suggest a 2" one for certain, as they can handle the extra heat loading a larger than 100mm scope puts out. I have 3 wedges, the Baader Mk I, the APM 2" Herschel Wedge (basically same as the current Baader models), and a Lacerta 2" (LAC-2S) Brewster angle wedge. I like them all, but My current favorite is the Lacerta. It has a wider imaging range (ND 4.07->ND6+ with a ND3 filter on it) and it works superbly well. 

 

Having said this, my recommendation to you as a first-time wedge owner, should you decide to go that way, would be the 2" Baader or APM wedges, as these also have a built in solar finder screen on the rear, and allow for a lot of flexibility and easiest to get using right away.

 

Good luck - I look forward to hearing your experiences once you decide, and can't wait to see a few nice shots you get too. CS, and good sun!

 

Darren

[MVoltae]

https://astrob.in/x4uwo6/0/

 

Here is a small refractor animation that I posted a few months ago.  Astro-Tech ED72ii refractor, Lunt Wedge, Baader continuum 540nm filter.  

[bujin9]

Actually...is there any danger (other than making sure I don't accidentally look into the OTA) to using a solar wedge on a C11 and viewing? Regarding optics, it's really just a back mirror, secondary and the front plate. 

[Sebastian_Sajaroff]

Actually...is there any danger (other than making sure I don't accidentally look into the OTA) to using a solar wedge on a C11 and viewing? Regarding optics, it's really just a back mirror, secondary and the front plate.

As far as I know, wedges only work on refractors

[gstrumol]

Actually...is there any danger (other than making sure I don't accidentally look into the OTA) to using a solar wedge on a C11 and viewing? Regarding optics, it's really just a back mirror, secondary and the front plate. 

Yes, a great danger to you and your optics! A Herschel wedge is to be used only on refractors!!!

 

If you want to use your C11 you should use a front-mounted solar film - either full aperture or covering a small, off-axis hole in a solid front cover.

[bujin9]

Ok...great!...glad I asked

[lajoswinkler]

Yes, a great danger to you and your optics! A Herschel wedge is to be used only on refractors!!!

 

If you want to use your C11 you should use a front-mounted solar film - either full aperture or covering a small, off-axis hole in a solid front cover.

The danger for a reflector does not come from the wedge, but from the fact the aperture is unshielded. 

[igorrr]

Today's granulation and spots

https://astronomy.ru...=media;in=19669

https://astronomy.ru...=media;in=19670

https://astronomy.ru...=media;in=19671

 

Wedge gives the ability to set exposure in 0,2-0,5 ms range, so some wind is not a problem and makes the picture even better by removing local heat build up.