Jump to content


Photo

Flats and solar mosaic: what a difference!

  • Please log in to reply
22 replies to this topic

#1 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 26 August 2013 - 11:21 AM

Hi everyone,

assembling a whole disk mosaic had been a headache. Daniel Borcard from Astro Quebec suggested to use flats in Registax to overcome the problem associated with the smaller prism B600 in my Lunt LS60. It made quite an improvement!

I know, this 15 august solar disk is outdated but I did not want to post it before, due to its complete lack of quality.

Here it is now thanks to flats.

https://dl.dropboxus...MozaicColor.jpg

Jean

#2 Peter Z

Peter Z

    Vostok 1

  • -----
  • Posts: 146
  • Joined: 03 May 2010
  • Loc: Winnipeg, MB, Canada

Posted 26 August 2013 - 01:07 PM

Hi Jean.


That's a beauty! Do you have a "Before" shot to compare with this fine "After" shot?

Cheers.
Peter.

#3 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 26 August 2013 - 01:24 PM

Here is the «before»...

https://dl.dropboxus...MOZ2ab copy.jpg

the transition between the four panels was almost impossible to get rid of...

Regards

Jean

#4 R Botero

R Botero

    Apollo

  • -----
  • Posts: 1296
  • Joined: 02 Jan 2009
  • Loc: Kent, England

Posted 26 August 2013 - 01:54 PM

Great result Jean! Well done.

Roberto

#5 Andy Devey

Andy Devey

    Mercury-Atlas

  • -----
  • Posts: 2794
  • Joined: 06 May 2011

Posted 26 August 2013 - 02:56 PM

Excellent work Jran and a great comparison, I am going to have to try those flats

Regards

Andy

#6 ASTROTRUCK

ASTROTRUCK

    Ranger 4

  • -----
  • Posts: 386
  • Joined: 02 Jan 2010

Posted 26 August 2013 - 05:54 PM

how were the flats used - what were the stages ?
some use the program imerge with settings (from posts by members) 256,25,0 with no merge lines - without flats.

thanks

#7 Paul Hyndman

Paul Hyndman

    Viking 1

  • -----
  • Posts: 556
  • Joined: 13 Jul 2004
  • Loc: Connecticut Shoreline USA

Posted 26 August 2013 - 06:13 PM

Wow Jean, that's gorgeous!!!

Thanks for sharing.

Paul

#8 BKMaynard

BKMaynard

    Vostok 1

  • *****
  • Posts: 183
  • Joined: 21 Feb 2013
  • Loc: Cahokia, Il. (st.louis area)

Posted 27 August 2013 - 12:08 AM

I never had any good results,with flats using Registax What's the trick?

#9 steveward53

steveward53

    Surveyor 1

  • -----
  • Posts: 1992
  • Joined: 14 May 2012
  • Loc: Newmarket,UK

Posted 27 August 2013 - 01:18 AM

Certainly irons out the wrinkles ...

#10 LarryAlvarez

LarryAlvarez

    Skylab

  • *****
  • Posts: 4129
  • Joined: 12 Aug 2005
  • Loc: Texas

Posted 27 August 2013 - 03:43 AM

Remarkably better than the before. :)

#11 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 27 August 2013 - 08:50 AM

I never had any good results,with flats using Registax What's the trick?


I choose a section of the sun with a minimum of features. I adjust the focus and do not touch it during the process.

I attach a white plastic bag in front on the telescope.

https://dl.dropboxus...93639/Flats.jpg

Using IC Capture I and the DMK camera I make sure the field is filled with the sun.

I then adjust the histogram of IC capture to have it in the middle (average grey).

https://dl.dropboxus.../IC Capture.jpg

I then shoot approx 500 AVI frames (named flats)

I continue my shooting session of the sun (without the bag of course).

In registax you have to open first the AVI flats and process as usual. No wavelettes. Save as bmp file (Flats)

You then load the bmp file as a flat in Registax. All your AVI files will then be automatically processed with this flat.

https://dl.dropboxus...9/RegistaxF.jpg

Et voilà! The rest is assembling the panels in PS which I do manually.

Hope this will help.

Jean

#12 astrovale

astrovale

    Surveyor 1

  • *****
  • Posts: 1985
  • Joined: 19 Feb 2006
  • Loc: Rimini, Italy

Posted 27 August 2013 - 09:17 AM

Wow Jean! What a great improvement! I think you should be very happy with this mosaic and of your newly acquired technique!

Well done!

Luca

#13 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 27 August 2013 - 10:41 AM

how were the flats used - what were the stages ?
some use the program imerge with settings (from posts by members) 256,25,0 with no merge lines - without flats.

thanks


Just tried the imerge program with the settings you mentioned. Terrific program indeed! But when used on my files without flats it won't perform very well. However, with my flat-processed files it seems superior to photoshop CS2 for merging.

So thank for the imerge tip!

Jean

#14 rigel123

rigel123

    Voyager 1

  • *****
  • Posts: 11322
  • Joined: 29 Jun 2009
  • Loc: SW Ohio

Posted 27 August 2013 - 12:07 PM

That is quite an improvement Jean! I haven't tried flats before, I may have to check that out!

#15 BYoesle

BYoesle

    Aurora

  • *****
  • Posts: 4965
  • Joined: 12 Jun 2004
  • Loc: Goldendale, Washington USA

Posted 27 August 2013 - 12:46 PM

Fantastic mosaic Jean! :jump:

#16 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 27 August 2013 - 03:08 PM

Thanks you very much everyone!

Jean

#17 BKMaynard

BKMaynard

    Vostok 1

  • *****
  • Posts: 183
  • Joined: 21 Feb 2013
  • Loc: Cahokia, Il. (st.louis area)

Posted 27 August 2013 - 09:05 PM

most helpful indeed!

#18 ASTROTRUCK

ASTROTRUCK

    Ranger 4

  • -----
  • Posts: 386
  • Joined: 02 Jan 2010

Posted 29 August 2013 - 08:17 PM

LONG POST - A FEW QUESTIONS

1)focus issue - out of focus to give a full field corner to corner of the disk out of focus to ensure no features ?? therefore making a flat @ 900mm giving a narrower field filling corner to corner with a flat bright even brightness corner to corner.

2)my scope is 100mm f9 - will use it as 900 but also 450 with reducer - do i then use the same flat in regi for an image @ 900 & full disk also at 500 ?? - read elsewhere cant change orientation of scope unless take new flat for processing with flats for each orientation.
apparently the corners need to line up when processing ?

3)in regi - the flat - is it after also converting it to a single image or as an avi flat ?

4)can i use a white garbage bag or must the plastic be partially transparent - is white bag too opaque ?

5) can i save the 1 flat to use in regi for all images both close up or full disk for all future sessions ?
again they seem to state need flat for every orientation of scope for different focal lengths & even if i only move tube if i close down then reopen for additional imaging.

no-one around here uses flats so cant see it in actual usage.
some of my images are not even across the field due to coronado sweet spot resulting from front etelon - edge darkening is ok but central brightening is not.

thanks for responses anyone .

#19 raylal

raylal

    Surveyor 1

  • -----
  • Posts: 1956
  • Joined: 19 Apr 2010
  • Loc: Cornwall, Ont., Canada

Posted 30 August 2013 - 06:35 AM

Wonderful and very helpful presentation Jean, well documented. Congratulations on the gorgeous results.
Well done !!!! and thank you.

Ray

#20 JeanB

JeanB

    Apollo

  • -----
  • Posts: 1330
  • Joined: 11 Jul 2011
  • Loc: Montreal, Canada

Posted 30 August 2013 - 09:07 AM

Hello ASTROTRUCK,

I am sure no expert on this but I will try to answer your question as best as I can, leaving other to correct me;

1)focus issue - out of focus to give a full field corner to corner of the disk out of focus to ensure no features ?? therefore making a flat @ 900mm giving a narrower field filling corner to corner with a flat bright even brightness corner to corner.

A: The focus has to be the same for the flats and for imaging. My understanding is that if you are out of focus for flats it will also displace the area you want to correct even in the corners.

2)my scope is 100mm f9 - will use it as 900 but also 450 with reducer - do i then use the same flat in regi for an image @ 900 & full disk also at 500 ?? - read elsewhere cant change orientation of scope unless take new flat for processing with flats for each orientation.
apparently the corners need to line up when processing ?

A: I haven't try flats yet for a different magnification.

3)in regi - the flat - is it after also converting it to a single image or as an avi flat ?

A: you first process avi flat in REgistax and convert the result as a bmp file. It is this file that you have to load before processing your solar avi. Registax will automatically use it.

4)can i use a white garbage bag or must the plastic be partially transparent - is white bag too opaque ?

A: I used a white garbage bag. It has to let sufficient light go through for your capture software to «see» it.

5) can i save the 1 flat to use in regi for all images both close up or full disk for all future sessions ?
again they seem to state need flat for every orientation of scope for different focal lengths & even if i only move tube if i close down then reopen for additional imaging.

A: I used the same flat for two different sessions but only for full disk. I worked nicely but it may have been a coincidence.

Hope this will help.

Jean

#21 R Botero

R Botero

    Apollo

  • -----
  • Posts: 1296
  • Joined: 02 Jan 2009
  • Loc: Kent, England

Posted 30 August 2013 - 10:58 AM

Astrotruck/Jean - re #1

I would suggest defocussing your scope to take the flats. This is the usual practice for night flats and certainly what has worked for me for daylight flats. I move the scope about little bit whilst capturing the flat movie to ease-out any features that may remain.

#5 - And I take a flat every time I change my settings or start a new imaging session. Flats are relatively easy to take (particularly daylight) - not like darks (or flats) for DSOs.

Roberto

#22 photiost

photiost

    Apollo

  • *****
  • Posts: 1104
  • Joined: 14 Dec 2006
  • Loc: La Belle Province, Canada

Posted 31 August 2013 - 08:03 PM


Very Nice work Jean

Felicitations !!

#23 ASTROTRUCK

ASTROTRUCK

    Ranger 4

  • -----
  • Posts: 386
  • Joined: 02 Jan 2010

Posted 01 September 2013 - 05:22 PM

if i take a flat at the beginning of a 3 hour session of different ha images with different settings - what happens if i use the same flat for the processing of all the different ha images taken -
if i need to lower the objective end to attach a plastic screen in front of the etelon, then direct the scope to the sun - then it moves a bit to attach a .5 reducer to the camera after imaging @ 900fl , then it moves a bit to attach a barlow in front og blocking filter for another magnified set of images

do i need to do a flat at each point - is the slight movement of the system at each stage an issue -
can i process all the images with the initial 1 flat taken @ 900 with a full frame flat image corner to corner
- if not what will happen if i use the same flat thruout the regi processes ?

what if i turn the camera 90 deg up verticle to ground at 4pm when telescope is at an angle - with barlow & camera the syatem wont hold them at 45 deg so i rotate the camera upward - does this again require another flat ??

regi has a flat field menu to create a flat field - is this in place of dong one before imaging -
loading a flat field - is this as the avi or after it is processed in regi to a single frame then loaded when processing the avi image for processing.

OK why isnt just one flat field good for the day ??
what happens if i do use just one ?

WELL no-one here uses them so no-one to ask or see the full process.

THANKS ALL






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics