Monday, 02 August 2021
  14 Replies
  226 Visits
0
Votes
Undo
  Subscribe
hello everyone
i m back from holidays and i spent some time checking the calibration file of pier1 as i get a lot of ampglow and vignetting using the classic wbbp batch of pixinsight

i found why there amp glow resulting in final file .
All the dark file have been taking at 0 gain . if you check the fits keyword , you can see electronic gain at 4.96e-/ADU which is gain 0 on ZWO 1600MM
The light subs are shoot at gain unity (1 e-/Adu) , gain 139 on ZWO scale.

thats why amp glow is not fully substracted using dark files, dark file are gettting 4x less data than in light file

i ve done a small test using pixel math with these formula to generate a scale dark : Raw-((dark300s-bias)*4+bias)
and after i sub this result image to a raw file of pier1 : --> no amp glow :)


Capture d’écran 2021-08-02 182025.png


Capture d’écran 2021-08-02 182046.png

Capture d’écran 2021-08-02 182100.png


i didnt succeed , yet , to use the flat files , i still got overcorrected vignetting


Steve , you have to redo the dark with the correct setting , same as light file. it will be simpler

Also , flat file have been done at unity gain , and i think you should do Darkflats for each of them. Bias are not use with Cmos camera to calibrate

cheers
florent
0
Votes
Undo
Florent,

Thanks for all the effort you've made to investigate this. Also for sharing the pixel math formula you used to create a scale dark. All this is way over my level of understanding but gives us good reason to believe that the current issues are all fixable.

Cheers,

Ray

Ray
Roboscopes Guinea Pig


2 years ago
·
#2964
0
Votes
Undo
for the flat , it is a little difficult to use them due the light leak on the left.
As this light is not present during the night , it completly mess the calibration of light frame.

i think the best is not use flat at all , but there is a lot of dust on the mirror.

difficult :)
2 years ago
·
#2965
0
Votes
Undo
Mount is retaking darks as I type, the camera does not have a shutter so they can only be done on dark moonless nights

this meant this evening was the earliest opportunity as they take 6 hours and the moon will still be out the way

Flats I am thinking about a solution :)

Steve

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


2 years ago
·
#2966
0
Votes
Undo
Phil is off on Holiday this week but I will do my best to get the new darks from last night zipped up and made available for download

If I manage I will let you know in the forum :)

but for now Pier 1 is back up and running

Re flats - at present we have a maintenance trip booked for the 22nd so if all else fails we will address the light leak in flats then if you can bear with us

Steve

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


2 years ago
·
#2967
0
Votes
Undo
flats in an open scope are difficult to do i think

you use a flat panel ?
2 years ago
·
#2968
0
Votes
Undo
We have a flat panel, roof flat system and of course we can take sky flats however in this case we believe its a small amount of light leak from the ZWO OAG that's causing the issue. None the less whatever the issue we will get it solved when we are there.

In the meantime we can try different ways of garnering the Flats in the hope of an interim solution

Problem solving remotely is never an easy thing to do LOL

Steve

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


2 years ago
·
#2969
0
Votes
Undo
Ok everyone, The flats issue on Pier 1


1,
After much testing it appears 2 of the 31mm unmounted narrowband filters have slipped position in the wheel causing a small amount of off-axis light to leek in, we have checked and this appears to be a very common issue with the ZWO wheel as the holder is a lot bigger than 31mm and the filter shield/holder does not always hold the filter in perfectly. So much so that an after market solution has sprung up to fix the issue!

https://buckeyestargazer.net/Store/FilterMasks.php
We have order these 3d printed centring holders from the USA

We are hoping they arrive in time for the next trip but just in case they do not arrive in time, I have also instigated a back up plan in the form of 1mm thickness O-rings which we can put round the unmounted filters

2,
This present s a small issue in so much as I doubt we will obtain decent flats for the 2 offending filters until we get to Spain and then to make matters a little worse it will make all previous flats void because we need to remove the wheel to do the fix.

3,
So there it is Boys n Girls, the solution with a slight bitter after taste I am afraid to say :( However once done this issue should not present itself again!

Steve

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


0
Votes
Undo
Phil is off on Holiday this week but I will do my best to get the new darks from last night zipped up and made available for download

If I manage I will let you know in the forum :)

but for now Pier 1 is back up and running

Re flats - at present we have a maintenance trip booked for the 22nd so if all else fails we will address the light leak in flats then if you can bear with us

Steve



Hi Steve,

Have the new darks been done as I cannot seem to find them.

Cheers, Ray

Ray
Roboscopes Guinea Pig


2 years ago
·
#2971
0
Votes
Undo
Yes, Phil is putting them on the server now Ray :)

They should be ready this afternoon

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


2 years ago
·
#2972
0
Votes
Undo
Just zipping now Ray - they will be in the normal calibration area and not on FTP

Phil McCauley
Roboscopes Website Admin


2 years ago
·
#2973
0
Votes
Undo
hello
i ve test the new dark frame on the tulip dataset . The ampglow is completly remove now , i even not use flats and registered file are ok :)

thanks for the new darks

Steve , you say that there is a collimation issue on the scope that will be adressed on the next trip ?
2 years ago
·
#2974
0
Votes
Undo
hello
i ve test the new dark frame on the tulip dataset . The ampglow is completly remove now , i even not use flats and registered file are ok :)

thanks for the new darks

Steve , you say that there is a collimation issue on the scope that will be adressed on the next trip ?


Awesome news on calibration

Yes, top left corner is just a little out from memory, we leave for Spain on the 22nd so will sort it that week :)

Steve

Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


2 years ago
·
#2975
0
Votes
Undo
anybody can test the M101 dataset ? i ve got very strange behavior of L flats ?

need to re test , may be i made an error but dust isnt corrected as it is on Green or Red channel
2 years ago
·
#2976
0
Votes
Undo
I ve found the prob .
all L data before the night of 29 july are way up in median level and the Flat doesnt correct very well the dust .
Capture d’écran 2021-08-10 213015.png

i didnt understand why the median level is rising on a line . it is like data are accumulated in each frame ...

i v resbumit correcting L data for M101 before this object diseaper
  • Page :
  • 1
There are no replies made for this post yet.
Be one of the first to reply to this post!

Follow Us

Newsletter

Proud to use

  • FLI

  • 656 Imaging

  • 10 Micron

  • Planewave

  • ZWO

Company Details:

Roboscopes

802 Kingsbury Road
Birmingham
B24 9PS
United Kingdom


Roboscopes is a trading name of ENS Optical LTD ¦ Copyright© 2020 Roboscopes