Username:

Password:

UKAI is moving to Facebook

Author Topic: A question about relative exposure lengths for LRGB imaging.  (Read 112 times)

0 Members and 1 Guest are viewing this topic.

Offline Annie

  • Poster God
  • *****
  • Posts: 1029
I hope shortly to make a start on my move from DSLR to CCD imaging with my Atik 460.  Until I get some experience is there such a thing as a general rule of thumb I can use to determine how long my luminance exposures should be compared to RGB exposures.  I assume it depends on the target but have read that to start with I can try luminance exposures twice the length of RGB ones.  Would that be a reasonable starting point for me?

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Offline chris.bailey

  • Administrator
  • Galactic Poster
  • *****
  • Posts: 10012
  • If at last you do succeed, don't try again
    • Rosemount Observatory
Re: A question about relative exposure lengths for LRGB imaging.
« Reply #1 on: 18:57:22, 10 August, 2018 »
Mmm. To be very honest, I would start with RGB and forget the L for now. Its a major post processing complication that you probably don't need for now. I rarely do L on common targets as the Binned 1 x 1 RGB combined already contained all the luminance information. In the bad old days of low sensitivity CCD's, it was commonplace to bin the RGB 2x2 to get an extra boost and take the L f1 x 1 or the resolution. Thats now a little old hat!

RGB filters reduce the light take compared to L so the L filter is already giving you a like for like boost boost. Sky background levels are the limiting factor when it comes to correct exposure so if the RGB is Sky Limited ( as they should be), shooting L longer still would be wasted. As a result I shoot the L frames the same length as the RGB or even a little less and shoot lots of them to get the noise threshold down in the L channel.

Hope that helps more than it confuses. Bottom line is, shoot RGB!

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Annie

  • Poster God
  • *****
  • Posts: 1029
Re: A question about relative exposure lengths for LRGB imaging.
« Reply #2 on: 19:45:36, 10 August, 2018 »
Think I've got the gist of that Chris but will shoot just RGB as I can well do without the post processing complication for now!

Thanks a lot

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

 

ukbuysellRemote Imaging from AustraliaSharpSkyblank APTUKAI on Facebook
Powered by SMF 2.0.15 | SMF © 2006, Simple Machines LLC
DarkBreak by DzinerStudio. Theme modified by The UKAI Team

Page created in 0.252 seconds with 36 queries.
TinyPortal © 2005-2012