First attempt Lunt 50 DS + ASI 174MM

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First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Hi all,

After all good advices on what mono cam to choose, I decided to go for ZWO ASI 174MM one.

It took some time, as continuously travelling (now on my way to Abu Dhabi F1 grandprix ;) ), but below my first attempt on 11 November sun.

Advices/remarks welcome, as I am struggling how to get rid of the ghosts.
The crop at least shows less of this problem.

Rgds,
Hans
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ZWO ASI  Prom 171111.png
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ZWO ASI  Prom 171111 crop.png
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by marktownley »

Yup. looks like it works - good images!


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Christopher »

Very nice Hans! How do you like the ZWO? What capture software are you using?


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Tnx to both for positive reaction...

I also am a kind of happy with first result, but yet a lot to learn.
Those ghosts bothering me, as I did not see them while making the avi, just because being in sunshine, but looked back last night and clearly visible in the avi. Guess this may have to do with DS tilting ?

Christopher: I have used Firecapture for this one, with settings: Gain=126, Exposure=61.1ms and Gamma=85.

Suggestions appreciated.

Note on ZWO 174MM:
I like the camera very much, my first round of testings was focussed on the moon (with evolution 6") and got some excellent results.
Only 1 session done on the sun sofar, to be continued once back home in the middle of next week..

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Montana »

These are beautiful images :hamster: :bow
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Carbon60 »

Lovely shots. Nice proms.

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

After just the proms, now time for the disk + proms from the same avi set shot on 11 November.

Shadows/Highlights helped me to reduce the ghosts a bit, but still not to the level I am looking for.

The attached pictures are yet my first attempt to make (almost) full disk + proms combined..

Wondering who was shining a with a flashlight on the sun from the top, but sure it wasn't me.... :shock:
No idea (yet) how to get rid of this, where it must be said I did use a flat.

As always, please come with suggestions to help me develop more..

Hans.

download/file.php?mode=view&id=29839
download/file.php?mode=view&id=29840
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[The extension tif has been deactivated and can no longer be displayed.]

Sun 171111 D+P v3.png
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by marktownley »

You need to tilt the external etalon a bit more


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Fear I am in need of some help, meaning good advice I fear.

Avi's shot on 02/12/17, decent seeing.

Following Marks' advice to tilt the DS unit a bit more, following results getting (no flats used as I am still struggling with them).

With the FD I managed to limit the ghosts a bit, but with half disk, when trying to get the proms out sharper and better, ghosts appearing in full glory.
Have been turning the DS unit about half way up, if more turning up I am loosing details on the disk and proms.

Anyone who can put me on the right track with some idea's ?

Hans
Attachments
Sun Final Sharpcap.png
Sun Final Sharpcap.png (6.25 MiB) Viewed 4219 times
P30 Gain=249_Exposure=3.8ms_Gamma=100_041609 FINAL COLOR.png
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Montana »

These are lovely images :hamster: :bow
have you tried rotating the DS unit around in comparison to the SS unit? I have to turn my PST DS etalon half a turn from being tight to get the ghost in a place where I can just tilt it out of shot without losing 'onband' too much.

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Hi Alexandra,

One time, I remember, I was reading such advise before, but did not remember untill now you are telling me...
Will give it a try today to see if this indeed may give better results.

Also remember that once I read somewhere that there is a possibility in PS (using CS2) to eliminate this problem.
Searching sofar on this PS option did not give me results.... pity.

Tnx for the tip, will let you know the outcome...

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by robert »

Do you get an even full disk SS using max contrast on gamma and over exposing slightly to show the bright area? If you can centre this as well as you can before adding the second etalon it makes and even disk possible in my setup at least.
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Hi Robert,

That is a good one to try as well, as DS went on to never be taken off anymore.... So have no clue what SS FD bringing me with this cam, as
with Skyris 132c I did not have this problem on SS and DS, but the ASI 174 is a different game as it seems. Perhaps because of larger chip ?

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by robert »

HansH wrote: Tue Dec 05, 2017 12:17 pm That is a good one to try as well, as DS went on to never be taken off anymore.... So have no clue what SS FD bringing me with this cam,
:? :?

I do this procedure every time as it is the only way I have found to get even disks
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

So I did my afternoon testing.... My "quick and dirty" processing DS result below.

Alexandra:
Loosened the DS unit slowly and after 1/4 rotation got an even illuminated disk. saw the ghosts starting to rotate as well, so giving options as you said.
Looks like considerably better than before, must be able to do better still, but already now a sheer win here. :bow2

Robert:
On Lunt 50, when SS, the uneven disk illumination is much less of a problem
I would not know, inexperienced as I am, how with a Lunt 50 to rotate/center the inner etalon. to my knowledge that is a fixed unit.....or is that at all possible ?

In general I can say that partially I think I am creating the ghost problem myself by lifting the gain slider too high at most times when recording.
Took it more easy this time, which I think attached picture showing.

Further comments welcome for sure.

Hans.
Attachments
Gain=172_Exposure=2.4ms_Gamma=100_155536_lapl3_ap333.png
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Montana »

That is a much more even disc Hans.

When you start off, start with single stack only. Tune the etalon to get maximum contrast over the disc as much and as even as possible. Now add the DS unit and tune again to get maximum contrast but the brightest image. If this is where the ghost is, then rotate the DS unit slowly around until the ghost is more away from the disc (but don't let it drop off!).

When imaging try to stick with the lowest gain (least noise) that you can. Keep the gamma as near neutral as possible but if lacking contrast lower it just a little, if looking at proms then you can increase it a little (but don't do too much as you will clip the histogram and lose data) - this can be replicated easily in post processing anyway. Then increase the exposure to best fill the histogram.

This is my work flow.

Alexandra


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by robert »

Alexandra puts it better than me, clearer that is!

Quote "I would not know, inexperienced as I am, how with a Lunt 50 to rotate/center the inner etalon. to my knowledge that is a fixed unit.....or is that at all possible ?"

I just meant tuning, not rotating anything. As you do pressure or tilt tuning the bright are moves across the disk and may even split in two as in your image. My advise was to get this area central before adding the second etalon. It is a fix for an uneven disk, it appears more even because the unevenness is central!

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Thanks for advices from both of you....

Robert: my misunderstanding on "center". sorry for that.

Today I wished I was able to do next testings, but too busy with work, so next is tomorrow on the agenda.
Shall keep you advised on proceedings.

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Starting to look more like it... Brightest spot in the middle.

Your advices were an eye opener as to usuage of the PT and DS unit a different way.

Alexandra:
Your advice is to use Gain -neutral-, guess in Firecapture that means slider all the way to the left ?
with slider all the way left, my screen stays dark and I see no disk, no matter how I slide up the Gamma and Exposure. Perhaps my laptop !!!!

As you can see in settings used, Gain 42 gave me a satisfying view on screen, yet you state the "neutral" one is better to preserve data.
With a Gain around 30 I reach the limit on screen.. You would consider slider 30-40 range good enough to get sufficient data ?

On this pic I deliberately did not sharpen in order to better see the lighter spot in the middle.

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by robert »

Looks much better to me. Nice
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Montana »

This image is the best you have done! great work.

Every camera is different Hans, for the Grasshopper lowest gain is 152 with the slider all the way to the left. This is why I can only say neutral gain and neutral gamma (no stretching) as every single make and model is different. The only way to find out what these pre set defaults are is to use the cameras own capture software, you open it up and see what the default settings are. Then copy them in Firecapture. Firecaptures opens initially with these default setting but as soon as you change them without taking a note at the time, then Firecapture will just remember what you last had it set at.

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Tnx for the input... seems like that problem tackled, just leaving my last issue to be solved.

In my flow I am making flat avi by defocussing just the FD I have in my view. not making f.e. flat avi from ROI to obtain full frame flat.
AS3 producing the flat FD image as shown in the png below.
When loading the flat once the disk opened, I am getting the result as shown in the AS3 png picture.

Another problem I have is that regularly AS3 is not even loading the flat it produced itself. a total mess.

Probably more of you may have been suffering from this, but a search here did not provide an answer.

What on earth am I doing wrong ?

Hans.
AS3 Disk + Flat.JPG
AS3 Disk + Flat.JPG (341.79 KiB) Viewed 4060 times
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Re: First attempt Lunt 50 DS + ASI 174MM

Post by Montana »

Flats are very difficult to do this way, I have never achieved it when there is such a big difference between light and dark. For a full disc it is much easier to let the disc of the Sun drift around in capture. This way any fluff or uneveness is spread and removed in the stacking software itself as it doesn't show up in every frame. I have only found flats to work in close ups with no black space in the frame. Maybe others have though?

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Re: First attempt Lunt 50 DS + ASI 174MM

Post by pedro »

An alternative is the artificial flat

I describe how to do it in my webpage

http://re.apaaweb.com/imaging_the_sun_PRe_2015.pdf

ARTIFICIAL FLAT-FIELD (Photoshop)
1. Open mosaic image (16-bit TIFF file) (Figure 19)
2. Create a new Layer (Figure 20)
3. Create a Mask (Figure 21)
4. Copy mosaic image to Mask
5. Apply a Median Filter (e.g. radius 25) (Figure 22)
6. Reduce Mask brightness (Curves) (Figure 23)
7. Apply Mask (Difference) (Figure 24)
8. Reduce Mask Opacity if needed (Figure 25)
9. Flatten Layers
10. Use Curves and/or Levels to adjust contrast and brightness (Figure 26)
11. Save flat-field corrected image (16-bit TIFF file)
12. Before/After (Figure 27)


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Thanks Pedro, much appreciated. This is a very well documented tutorial, I did not know yet.
Will try tomorrow for sure.

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by _Zakalwe »

HansH wrote: Thu Dec 07, 2017 4:41 pm

Your advice is to use Gain -neutral-, guess in Firecapture that means slider all the way to the left ?
With Firecapture the neutral point for the ZWO 174 camera is 50 on the gain.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by PDB »

Hi,

think you are mixig gain and gamma here. For the ZWO cameras the neutral (or linear) gamma (not the gain) is 50. Can also be set in Firecacture by setting Gamma to off.

Rgrds,

Paul


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by HansH »

Hi,

In my last picture (see settings used under picture) my Gamma was at 50, so seems I found the neutral setting for that one.
Since lower than 30 on Gain gives me almost black screen, I finally worked with 42 as setting, relatively close to 50 as _Zakalwe mentioning..

The seeing condition is influencing a lot on settings I learned over the weekend...

Hans.


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Re: First attempt Lunt 50 DS + ASI 174MM

Post by _Zakalwe »

PDB wrote: Mon Dec 11, 2017 12:33 pm Hi,

think you are mixig gain and gamma here. For the ZWO cameras the neutral (or linear) gamma (not the gain) is 50. Can also be set in Firecacture by setting Gamma to off.

Rgrds,

Paul

Oops....so I am.
My apologies and thanks for the correction


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