Creating Master Flat issues

[Tinbeard]

Hi,

I'm new to Pixinsight and I'm having real trouble creating a master flat 

I've been following the method outlined here http://pixinsight.com/tutorials/master-frames/en.html but when I try to create the master flat I get the message 'Error: incompatible image geometry' in the process console after which Pixinsight hangs.

If I don't select the calibration check boxes in the master dark and bias areas the process completes but I get the following warning:

** Warning: No correlation between the master dark and target frames.

But the resulting flat frame appears to be uniform should it not have some vignetting ?

I've tried it with flats taken at different ISO's and also different file types, CR" and TFF but still no luck 

Am I missing something here ?

[Cleon_Wells]

Tinbeard, check this link out,

http://www.astrofoto.es/Adler/Documentation/Calibration/Calibration.xpsm

this came from Vicent. Are you working with DSLR images; if so, leave the Bias check box uncheched.
I am also kind of lost when it comes to understanding all the correct settings of IC.
Cleon

[MikeP]

Hi Cleon,

What should I use to read what's at the other end of the link?  Clicking from within Firefox results in a page of XML.

Thanks

Mike

[Cleon_Wells]

Mike, this is not a web page it's just a list, step by step of what Vicent did with the subs he provide us, us being those that attend the Adler conference. The Adler conference was a great experience for me even though it was over my head, I had only used PhotoShop to process my subs before I purchased PI.
Cleon

[Cleon_Wells]

AstroPixel, this is where I read that the  CAL box in the Master Bias section must be unchecked, this is a little confusing because you have to check the Master Bias box  to enable the bias section but you  do not check the Cal box in the Bias section.
Cleon

 As we are going to subtract the master bias pedestal to the dark frames, only the <i>Master Bias</i> section must be activated (deactivate the <i>Overscan</i>, <i>Master Dark</i> and <i>Master Flat</i> sections, we're not going to use them). In the main field of the <i>Master Bias</i> section we will select our master bias image (this is done by clicking on the triangle just right of the field) from our hard disk drive. Last, the <i>Calibrate</i> checkbox in the <i>Master Bias</i> section must be deactivated; this is for calibrating the bias with the overscan, but DSLR cameras don't have overscan areas.

[astropixel]

I have to rush out the door to work. And in hindsight this subject always leads to anxiety This might help.

http://pixinsight.com/forum/index.php?topic=2564.msg17291#msg17291

[Tinbeard]

Hi Cleon,

Thanks for the link, that makes thing a bit clearer for me, I resolved the incorrect geometry error by taking some flats using nebulosity ( I used this to capture the lights and darks) and it seems to have done the trick.

I'm still not sure about the flats I've taken as the master flat just looks uniform, no vignetting or dust spots  

I've spent 2 days trying to process some images of Bodes Nebula and so far I haven't got past the creation of master Darks, Flats and Bias, there seems to be a lot of conflicting views on the process and what to tick and what not to tick in the ImageCalibration and ImageIntegration tools, I'm sure it will fall into place soon.

I am using DSLR images so as I understand I need to tick the Master Bias but not the calibrate check box within this section, is this just when calibrating the light frames or for darks and flats as well ?

Marc

[Tinbeard]

Hi Astropixel,

That's the guide I've been using but when I get to the 'Master Flats' section if I activate the calibrate checkbox in the Master Dark section the process generates errors, can't remember exactly what the error says, I'll run the process again and post the exact message but after these errors Pixinsight hangs.

To be honest I'm new to the whole dark, flat, bias arena so a lot of my issues may be with my understanding of what I should be seeing in these master frames. The Master flat is the one that is puzzling me as I expect to see vignetting and dust spots but it just appears to be uniform.

Marc

[Cleon_Wells]

Marc, did you calibrate the individual dark subs before you integrated them?
Attached is a single Flat sub before and after I calibrated it, yes this is and odd thing todo but I also have calibrated an individual Dark sub without the Master Flat section, the Calibrated Dark sub has zero level in it. The Flat I just did started out with a average level of 0.017 , top image and after Calibration , the bottom image, I have a average level of 0.0015. Also note that this Flat is  an iso100 flat.
Cleon

[astropixel]

Are the errors during light calibration or calibration of flats? I would suggest reading all of Juan and Vicent's posts on this subject. Juan does state that master frames must be processed natively in PI. So darks produced with other programs and introduced to PI may cause errors.

Referring to the tutorial and posts, once the flat has been calibrated using master bias/dark there is no further need for calibration, therefore leave the check boxes unchecked for light calibration. However, if flat frames have not been calibrated with the master bias and dark, then there has been no calibration of the master bias and dark frames - check the Calibrate boxes when calibrating lights - to put it another way.

The flat issue has me puzzled also - same issues as you. I'm about to embark on a few experiments I have in mind and try and isolate the issues. Fundamentally, if I introduce a flat into the system it affects the final MRS noise evaluation during image integration or fails to continue integrating.

[Tinbeard]

Cleon, I followed the process in the link you posted and it worked  All the master files created as expected and the final image has all the vignetting removed as well as the dust spots so the master flat did it's job !

Astropixel, the errors were generated when I was at the master flat (1) step, if I removed the tick from  the calibrate box in the master dark section the process completed but the resulting master flat was ineffective.

Thanks for all you help and advice, I really appreciate it.

I may even post the finished image if I can pluck up the courage 

Marc

[astropixel]

Cleon and Marc - many thanks.

Now that I've had time to read it at length, the link that Cleon provided is invaluable. It contains all of the information that I have been attempting to read into/extract/confirm from Vicent's basic tutorial. I wish that I had known of it sooner. All the essential detail is there. Really very deserving of a tutoria/how to.

[Cleon_Wells]

Marc and Astropixel ,  I’m glad to hear you’re getting some positive results with IC, thanks to Vicent. Understanding PI IC has got to be almost as important as good focus and good guiding because a small error in calibrating each sub with the same calibration error adds up to a big problem after integration. I have had some success with IC, calibrating  my poor quality subs taken with seeing no better then mag 4 visibility. I’m semi retired so I have time to try different combinations of iso settings, different exposure times  and different image levels, I change the converted DSLR level with the brightness setting in the DSLR_Raw settings.  I change the brightness setting from 1.0 to 4.0,  this change gives 14bit DSLR saturated stars a converted level of 1.0 instead of 0.25. Right now I’m trying to come up with a way to check IC and my Master Calibration files by  calibrating a single Dark sub and then a single Flat sub. I think the Dark_c sub looks correct to me with a 0.0 level. On the Flat_c sub I can remove the dust donuts and the vignetting  but I haven’t figured out what the correct overall level should be  for the Flat_c sub.
Cleon

[astropixel]

Retirement some distance off. Very little time to devote to this absorbing interest - wish there was more. Maybe I'm looking in the wrong places for information and look forward to hearing about your findings/processes.

[Tinbeard]

I agree the link provided by Cleon is absolutely essential reading for anybody starting out with the ImageCalibration and ImageIntegration tools, do you know if it exists in a more readable format ?

Retirement still quite a way of for me as well, I'm hoping by the time I retire I'll have got to grips with everything in Pixinsight 

Marc