15 replies to this topic

[revans]

Today was clear with decent seeing, maybe 3/5.  I set up my Lunt100MTDS with a 3x barlow and my 174MM camera.  I spent about 2 hours on one limb region but trimmed it back to 1 hr 45 mins in post-processing.  For some reason, I get a bit of a shadow in the FOV that is impervious to my changing cameras or barlows or not using a barlow. It isn't caused by Newton rings... I have a Newton corrector in the imaging train.  My current thought is that it must be caused by my having an imperfect etalon adjustment in double stack mode with this setup.  But that might not be the answer either.  
 
It is a fun hobby, but it can be frustrating.  I have to take some consolation in the animation otherwise being an improvement on prior efforts of mine.  But that shadow is something I'd like to lose.  I don't think it is dirt because it is there no matter which barlow or camera I use.  The image is a link to the animation on my Astrobin page.
 
Rick
 

 

Here is what my setup looks like:

 

 

[revans]

Here is a "close-up" of the active filament shown above, as an animation over the 1hr 45 min time-lapse.  Again, the image is a link to my Astrobin page.
 
Rick
 

[revans]

And finally, here is an animated close up of the prominence (1hr 45 mins) with the same setup.  This is another Astrobin link to my page.
 
 
Rick

[BobbieLunt]

Looking Great.  We also have the Lunt 100mm mtds scope and hope to start imaging soon. Don't yet have a camera. We'll borrow some from the Milwaukee Astronomical Society and start experimenting. 

[revans]

Looking Great.  We also have the Lunt 100mm mtds scope and hope to start imaging soon. Don't yet have a camera. We'll borrow some from the Milwaukee Astronomical Society and start experimenting. 

I've mostly done deep sky and a little lunar/planetary imaging but solar is something I've only tried over the past year.  In that time I've accumulated a Quark Chromosphere filter, the Lunt100MTDS and a Lunt40 double stacked scope. Learning to tune the Quark was difficult as I had the misconception that proper tuning would be near the middle of the tuning knob's range (actually it was much more to the left or bluer wavelengths for me so far).  The Lunt pressure tuned etalons used double stacked were a real challenge for me to get right, and I still may not have it quite right after a year.  But the tilt tuned front stacked etalons on the Lunt 40 (used double stacked) are much easier to figure out. Now I'm trying to use both the Quark and the Lunt 40mm etalon simultaneously on several of my refractors.  It all takes time.

 

I know how to use the Lunt100MTDS pretty well in the native double stack configuration without a barlow.  When I add a barlow, for some reason that I still don't quite understand, I get unwanted shading usually in two broad swaths, across my camera FOV. It happens no matter which camera or which barlow I use.  They are not caused by Newtons rings.  If I can eliminate these shadows, then I'll feel happy that I finally know how to use the Lunt100MTDS... but I'm not there yet.

 

Good luck with your solar imaging.  I think you will want a monochrome camera.  For full disk images at F/7, maybe something like the ASI178MM which has a pixel size of 2.5 microns is an OK compromise although I think there are better choices that I haven't tried yet.  When I add a barlow lens for F/17.5 or F/21 (if the seeing allows it and I want more of a close-up view) I've been using my ASI174MM which has larger pixels at about 5.86 microns although I think there are better choices.  I'm finding it isn't necessarily just a matter of matching focal ratio to camera pixel size.  Available ROI sizes and camera speed and noise seem important considerations as well.  Nothing in life is simple.  Sooner or later I'm going to look into these Player1 cameras etc. that solar imagers seem to gravitate towards.

 

Rick

[BobbieLunt]

Thank you for your information. We just got the Lunt in December last year and haven't worked with it as much as we would like. Finding that tuning the DS hasn't been too difficult, but we aren't adding any additional optics or cameras yet. We like the view we are getting with a 36mm Celestron Plossl. Thinking about getting the Lunt set of eyepieces. 

 

We have access to two solar telescopes at the Milwaukee Astronomical Society observatory, one is a DS Lunt 80mm scope. They have cameras we can borrow and several people well versed in using the equipment. We're hoping to learn from them. We'll be posting progress and pictures as we learn. 

[revans]

Here is a close up animation of a very small solar filament from that session. The image links to my Astrobin page.
 
Rick
 

[hopskipson]

And finally, here is an animated close up of the prominence (1hr 45 mins) with the same setup. This is another Astrobin link to my page.


Rick

I think the dark shadows you are getting are from Newton’s rings. They are very prominent in the animation above. You said you are using something to eliminate the rings. I assume it is a tilting mechanism. Maybe you have excessive tilt in the focuser and it negates the tilting mechanism. I notice I get more rings when I use a higher focal ratio.

[revans]

I think the dark shadows you are getting are from Newton’s rings. They are very prominent in the animation above. You said you are using something to eliminate the rings. I assume it is a tilting mechanism. Maybe you have excessive tilt in the focuser and it negates the tilting mechanism. I notice I get more rings when I use a higher focal ratio.

I know about the fine Newton's rings best seen in the sky background, but I'm talking about two large bands of diffuse darker shading I get across the solar disk using a barlow.

 

I've tried to get rid of them using many etalon adjustments in the double stack and it doesn't work.  I still have these two broad shade swaths across my image (I've done my best to process them out and what you see is their residua) involving the body of the sun.  They look the same with all cameras, all etalon settings, and all barlows.  They are a puzzle I can't seem to solve.

 

I've circled one of these shading areas I want to lose in red:

 

 

Rick

[0ak3]

I've mostly done deep sky and a little lunar/planetary imaging but solar is something I've only tried over the past year.  In that time I've accumulated a Quark Chromosphere filter, the Lunt100MTDS and a Lunt40 double stacked scope. Learning to tune the Quark was difficult as I had the misconception that proper tuning would be near the middle of the tuning knob's range (actually it was much more to the left or bluer wavelengths for me so far).  The Lunt pressure tuned etalons used double stacked were a real challenge for me to get right, and I still may not have it quite right after a year.  But the tilt tuned front stacked etalons on the Lunt 40 (used double stacked) are much easier to figure out. Now I'm trying to use both the Quark and the Lunt 40mm etalon simultaneously on several of my refractors.  It all takes time.

 

I know how to use the Lunt100MTDS pretty well in the native double stack configuration without a barlow.  When I add a barlow, for some reason that I still don't quite understand, I get unwanted shading usually in two broad swaths, across my camera FOV. It happens no matter which camera or which barlow I use.  They are not caused by Newtons rings.  If I can eliminate these shadows, then I'll feel happy that I finally know how to use the Lunt100MTDS... but I'm not there yet.

 

Good luck with your solar imaging.  I think you will want a monochrome camera.  For full disk images at F/7, maybe something like the ASI178MM which has a pixel size of 2.5 microns is an OK compromise although I think there are better choices that I haven't tried yet.  When I add a barlow lens for F/17.5 or F/21 (if the seeing allows it and I want more of a close-up view) I've been using my ASI174MM which has larger pixels at about 5.86 microns although I think there are better choices.  I'm finding it isn't necessarily just a matter of matching focal ratio to camera pixel size.  Available ROI sizes and camera speed and noise seem important considerations as well.  Nothing in life is simple.  Sooner or later I'm going to look into these Player1 cameras etc. that solar imagers seem to gravitate towards.

 

Rick

Re banding: Have you tried putting the tilt adapter after the Barlow, just before the camera sensor? 

[revans]

Re banding: Have you tried putting the tilt adapter after the Barlow, just before the camera sensor? 

No, but I will next time...

 

Rick

[0ak3]

The other thing is to watch out for a light leak into the tilter, which has an open edge. It can be covered with a cloth or something of that nature. 

[revans]

The other thing is to watch out for a light leak into the tilter, which has an open edge. It can be covered with a cloth or something of that nature. 

Do you mean the tilter on the Newton ring corrector or the tilt adjustment knob on each etalon? I'm assuming you likely mean on the Newton ring corrector unit.  Thing is, originally I put the Newton Ring corrector on because I wanted to try and get rid of this shading and some Newton rings that were out of control.  So, the shading seems to have preceded using the Newton ring corrector. At least if my memory is trustworthy.... which sometimes it isn't. 

 

Rick

[0ak3]

The newton ring corrector. Iight leak there is probably not the source of the banding, but easy to test.

[hopskipson]

I know about the fine Newton's rings best seen in the sky background, but I'm talking about two large bands of diffuse darker shading I get across the solar disk using a barlow.

 

I've tried to get rid of them using many etalon adjustments in the double stack and it doesn't work.  I still have these two broad shade swaths across my image (I've done my best to process them out and what you see is their residua) involving the body of the sun.  They look the same with all cameras, all etalon settings, and all barlows.  They are a puzzle I can't seem to solve.

 

I've circled one of these shading areas I want to lose in red:

 

 

 

Rick

That looks like a Newton ring.  If you increase the gain, you will see it more prominently in the dark area around the sun. Which tilting mechanism are you using? If it's not the Player 1 built into the camera body, then it needs to be right after the camera.

[revans]

That looks like a Newton ring.  If you increase the gain, you will see it more prominently in the dark area around the sun. Which tilting mechanism are you using? If it's not the Player 1 built into the camera body, then it needs to be right after the camera.

I think it is a ZWO tilt adapter plate.  I'll attach it directly to the camera.  I had started out using it that way initially and over time it ended up further away for some reason.

 

Rick