Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Disaster on PacMan (NGC281)

  • Please log in to reply
29 replies to this topic

#26 limeyx

limeyx

    Messenger

  • -----
  • topic starter
  • Posts: 458
  • Joined: 23 May 2020
  • Loc: Seattle, WA

Posted 24 September 2020 - 02:36 PM

On my canon i had to overexpose to get descent flats, 2 stops

 

ADU of canon800d sensor is max 16384 if am i not mistaken , you need flats about 7500 to 9000 ADU, roughly 40 better just below 50%

 

So you need to know what is the ADU for your camera .

 

That is what i learned sofar.

 

i made them using a computer screen, started up paint wich present a white background....put the scope as close as  i could..

 

Gave up the white T-short method...

I used an iPad with a white screen for my first flats and got horrid vignetting in the final image. Then tried diffusing it with a T-shirt and it doesn't feel very reproducible.

 

How are you checking the ADU values ? I am guessing Pixinsight has a way -- going to look into that



#27 limeyx

limeyx

    Messenger

  • -----
  • topic starter
  • Posts: 458
  • Joined: 23 May 2020
  • Loc: Seattle, WA

Posted 24 September 2020 - 02:37 PM

actually, I gave up the t-shirt method and bought a second hand light box which works just fine

Do you find you have to diffuse the light with cloth or translucent plastic or anything ? I heard a lot of these have uneven light or flickering LEDs which are hard for humans to see but ruin the flats



#28 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 6,478
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 24 September 2020 - 02:42 PM

I used an iPad with a white screen for my first flats and got horrid vignetting in the final image. Then tried diffusing it with a T-shirt and it doesn't feel very reproducible.

 

How are you checking the ADU values ? I am guessing Pixinsight has a way -- going to look into that

Iris

 

 

View - histogram

 

 

You can open (load) a CR2 canon raw file 

Attached Thumbnails

  • ADU.JPG


#29 Boeglewatcher

Boeglewatcher

    Vostok 1

  • -----
  • Posts: 102
  • Joined: 30 Jul 2020
  • Loc: Regensburg, Germany

Posted 24 September 2020 - 02:46 PM

Do you find you have to diffuse the light with cloth or translucent plastic or anything ? I heard a lot of these have uneven light or flickering LEDs which are hard for humans to see but ruin the flats

no, I use the Geooptik flat field generator (a little dimmed) directly in front of the lens. works like a charm.



#30 limeyx

limeyx

    Messenger

  • -----
  • topic starter
  • Posts: 458
  • Joined: 23 May 2020
  • Loc: Seattle, WA

Posted 24 September 2020 - 03:05 PM

Iris

 

 

View - histogram

 

 

You can open (load) a CR2 canon raw file 

 

 

no, I use the Geooptik flat field generator (a little dimmed) directly in front of the lens. works like a charm.

Awesome to both of you !


  • F.Meiresonne and Boeglewatcher like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics