Return to the Cloudy Nights Telescope Reviews home page


Astrophotography and Sketching >> Solar System Imaging & Processing

Pages: 1 | 2 | 3 | (show all)
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5926982 - 06/18/13 08:17 AM

Zam, I checked your Flickr again.

What changes did you make from March to May to almost rid the image from "onion rings"?

There seem to be a lot of conflicting stories/posts online in regards to that. But with you having practically the same setup, I wanted your views on the matter.

Thanks.


Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5927069 - 06/18/13 09:09 AM

Could you list the images with the onion ringing? I'm not sure which ones you are referring to.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: zAmbonii]
      #5927209 - 06/18/13 10:37 AM

The "Saturn Animation sneek peek" on 3/30/13 has some on the left side of the sphere, where as the one from 5/25/13 seems to be much better.

I have the onion ringing on the left side of mine as well.


Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5927659 - 06/18/13 02:30 PM

got ya.

Its because the collimation was not spot on.

This goes into the whole experience thing. Before I got the ASI camera I never really gave Saturn a try because it was too dim for my webcam. Then I got the ASI camera and now I had the chance to image Saturn a bunch you start noticing things. At first I attributed it to bad seeing because I really had nothing else to pin it on.

Then I had images before and right after a meridian flip, and there was a HUGE difference between the quality of the images. Then I decided it HAD to be mirror shift in the 8SE when doing the meridian flip.

I have to be honest. For the past several years I totally ignored collimation with the scope. When I first got it, I wasn't sure that I was going to keep the scope and I was intimidated with the collimation. Didn't have any Bob's Knobs and didnt want to mess around with a screwdriver so I never messed with the collimation.

Thing was, I was imaging with the webcam and the images I got were "good enough", I could always use the excuse of having a webcam or blame bad seeing for not that great images. I would get those type of edges on one side of Jupiter, but I saw them on a lot of images here in the forums. Sometimes you get that hard edge because from the bright edge of Jupiter (or so I thought) .

It wasn't until shooting Saturn with the new camera I noticed the edges, sometimes it was bad, sometimes not noticeable. Because there are a lot of hard edges because of the rings of Saturn, it became noticeable. On some images it would look like there was a second image of Saturn superimposed on the main image. It wasn't until this that I realized it had to be bad collimation.

So I got a set of Bob's Knobs and really started to pay attention to collimation. Before imaging I now check the collimation and if I do a merdian flip, I check it and adjust it again. If you do a meridian flip, it will most likely be out of collimation.

To test this, one night the scope was collimated pretty well and I took a video and processed, and then at the meridian flip, I took another image WITHOUT adjusting collimation and processed it and there was a HUGE difference in quality. You can see it from the image below: Top is after the meridian flip and without recollimating and the bottom is before the meridian flip with good collimation. The stuff on the left is what Metaguide showed when Collimating on Arcturus high in the sky.

Also, you need to make sure to collimate on a star that is high in the sky. I did a few times trying to collimate on Spica and the collimation was not quite perfect. There was a difference in collimation when I then slewed to Arcturus and checked.



Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 [Re: zAmbonii]
      #5927926 - 06/18/13 04:59 PM

I've had the 8SE for 2 years now, and the only way I've checked collimation is with a visual star test. Unfocusing for that doughnut shape.

Also, last night I tried the camera settings you mentioned with the histogram, and with gain at ~70, exp - 30 and gamma at 50, I was only getting about 38%..

I had to move gain to 100 to get 48% histogram, but Saturn looked really, really bright and over-exposed.

Thoughts?


Post Extras: Print Post   Remind Me!   Notify Moderator  
hopskipson
Pooh-Bah


Reged: 06/24/10

Loc: Queens, New Yawk, Light pollut...
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5928259 - 06/18/13 09:04 PM

Thanks zAmbonii and Matt, I'm learning a lot from this thread . I just installed my Bob's Knobs and collimated for the first time on Spica (oops). My seeing in the city is horrible but I keep hoping and practicing.

Post Extras: Print Post   Remind Me!   Notify Moderator  
BKBrown
Post Laureate
*****

Reged: 08/23/09

Loc: Northern Virginia, USA
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5928456 - 06/18/13 11:45 PM

A very good effort Matt, especially the Saturn image. The lunar shots are rather dark on my monitor, but that's an easy fix...

Clear Skies,
Brian


Post Extras: Print Post   Remind Me!   Notify Moderator  
lunar
Carpal Tunnel


Reged: 07/03/10

Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5928520 - 06/19/13 12:33 AM

Nice images!

Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5928944 - 06/19/13 10:28 AM

Quote:

I've had the 8SE for 2 years now, and the only way I've checked collimation is with a visual star test. Unfocusing for that doughnut shape.

Also, last night I tried the camera settings you mentioned with the histogram, and with gain at ~70, exp - 30 and gamma at 50, I was only getting about 38%..

I had to move gain to 100 to get 48% histogram, but Saturn looked really, really bright and over-exposed.

Thoughts?




After using Metaguide I have gotten pretty confident with my collimation, and it is pretty easy also. I collimate with the Barlow in place, make sure my finder is well aligned and immediately slew to Saturn and I'm ready to go.

Gain @ 100 and exp @ ~33ms is where I image at... ~50% histogram. @ 50%it shouldn't be too bright and can always be adjusted in post-processing.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: zAmbonii]
      #5929386 - 06/19/13 02:21 PM Attachment (14 downloads)

OK, Here is what I got so far.

It seems that I STILL have the onion ringing on the left side of Saturn, no matter the tilt.

The top image is last night.

640x480
10-100ms ex
Gain - 75
Ex - 39
Gamma - 50
Histo - ~50%
25 fps
4000/9000 stacked
AS!2
Wavelets is R6


Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5929498 - 06/19/13 03:09 PM Attachment (10 downloads)

Also, a shot of Copernicus. (My first)

Please feel free to share more opinions and techniques.

Thank you.


Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5929538 - 06/19/13 03:29 PM Attachment (10 downloads)

Another nice one.

It may be hard to see, but your "onion rings" I still think are a byproduct of the collimation being off a bit. And to me I think your changing of the orientation of the camera confirms it.

Look at the image below. What you are calling the onion ringing is what I call a shadow. Remember when I said when collimation is off, it looks like there are muliple images of Saturn superimposed?

Imagine taking a copy of Saturn and shifting it a few pixels in the direction I have the blue arrows. That copy is faint and you can't really see, it shows up in the contrasty portions of the planet, i.e. the rings and the edges of the planet itself.

Look at where I drew the red lines, those portions where it seems to be a faint dark ring is not really real, it is the actual rings and edges offset in the direction of the arrow. Its not noticable that much in the bottom image, because the direction of the offset is in the long axis of the planet.

It is more noticeable in the top image because you changed the orientation of the camera. I would try to comment more, but I have to prepare in trying to capture an ISS transit of the sun in about 2 hours .

You also can see in the new image the difference in keeping the gamma to 50. The top image looks more like a globe and less like a flat disc and the area near the equator is a lot brighter.

Edit: look at the image I posted earlier with my scope way out of collimation, it is an extreme example of what I am talking about

Edited by zAmbonii (06/19/13 03:38 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Space Cowboy
Pooh-Bah


Reged: 05/30/10

Loc: Cheshire, UK
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: zAmbonii]
      #5929570 - 06/19/13 03:54 PM

Very good Saturn images Matt!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Space Cowboy]
      #5929608 - 06/19/13 04:13 PM

I downloaded Metaguide this afternoon after the image still had the offset look. There hasn't been a cloud in the sky all day so if it holds up, I will attempt to use it tonight.

And thanks Cowboy. I'm still workin on them


Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5929648 - 06/19/13 04:37 PM

I think that your collimation is only slightly off, it may not be enough to be able to tell just using a defocused star. Thing is that these cameras now are so good that anything slightly off you can tell .

I'm frustrated as heck right now, I have the scope out and I'm trying to set up, but there is one freaking cloud that is blocking the Sun....AND IT ISN'T MOVING! Been like that for the last 15 minutes. I have about 50 minutes till the ISS pass....so it better get moving!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: zAmbonii]
      #5929667 - 06/19/13 04:50 PM

Will metaguide be able to pull out that detail.. I read their subject on collimation, about how the "doughnut" wont always tell if it collimated. Makes sense as my doughnut is pretty well spot on when I compare it with other star tests online.

Still no clouds here. Is it only visible from the northern locations?


Post Extras: Print Post   Remind Me!   Notify Moderator  
WarmWeatherGuy
Carpal Tunnel
*****

Reged: 08/27/11

Loc: Orlando, FL 28 N, 81 W
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5929674 - 06/19/13 04:53 PM

As an experiment you could cause your collimation to be noticeably out of alignment and then see what RegiStax gives you. I would do it myself but don't expect to be able to see anything but the bottom of clouds for the next few months.

Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: WarmWeatherGuy]
      #5929927 - 06/19/13 07:37 PM

ISS passes are all dependent on your location. You need to go to Heavens Above or Calsky, enter your coordinates and they can do searches to give you any ISS transit opportunities. 3-4km can mean the difference between seeing a transit and having it miss.

Was able to get the transit on video, although clouds did threaten to ruin it. Spent the last couple of hours trying to find Mercury. Got Venus and did get some of Mercury, don't think they were good captures, the wind started picking up a bit.

Gonna try Saturn and the Moon when things get dark.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Smittty692k4
Pooh-Bah
*****

Reged: 07/05/11

Loc: East Bernard, TX
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: zAmbonii]
      #5929980 - 06/19/13 08:14 PM

I capture my first white light solar images, but they are all blue. Too much or too little of something?

Post Extras: Print Post   Remind Me!   Notify Moderator  
zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: Moon and Saturn. 8SE/ASI120MC 6/16/13 new [Re: Smittty692k4]
      #5930002 - 06/19/13 08:29 PM

My images with a solar filter in are a bit blue also. When I was doing the transit, I just turned down the blue channel a bit and made things white.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | (show all)


Extra information
7 registered and 14 anonymous users are browsing this forum.

Moderator:  TG, Starman81, bilgebay, WOBentley 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1347

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics