Re: Qustion - color balance with SX HX916 and Astronomik RGB filters


Sep 30, 2004

 


----------------------------

#14017 Sep 30, 2004

Could anyone who is using the above combination help me with

achieving proper colour balance on my images? In particular, what

values should be used with color balance command?



I know I should take image of one of the reference G2V stars and

measure values for my particular setup, but it was cloudy here for

the last few weeks and I would love to properly process my previous

images.



Best reagrds,



Pawel Lancucki

Warsaw, POLAND



----------------------------

#14021 Sep 30, 2004

Hi Pawel,



You don't mention the scope you're using, but I got surprisingly

similar values with my 8" Meade SCT and TV101 (4" apo refractor) from

G2V calibrations:



Red: 0.68

Green: 1.00

Blue: 0.85



I.e., 1.47:1.00:1.18 RGB color or exposure weightings.



Hope this gets you in the ballpark.



-Marc

--- In MaxImDL@yahoogroups.com, "plancuck66" pawel.lancucki@p...> wrote:

> Could anyone who is using the above combination help me with

> achieving proper colour balance on my images? In particular, what

> values should be used with color balance command?

>

> I know I should take image of one of the reference G2V stars and

> measure values for my particular setup, but it was cloudy here for

> the last few weeks and I would love to properly process my previous

> images.

>

> Best reagrds,

>

> Pawel Lancucki

> Warsaw, POLAND



----------------------------

#14033 Oct 1, 2004

Marc,



Thank you very much.



I use Takahashi FS102 and FS60C and plan to acquire FSQ106 shortly. I

do take RGB exposures of the same duration for the dark calibration

simplicity (only one set of darks for the whole session).



Just additional question - by "Red: 0.68" you meen that I should

multiply R by 0,68 (equivalent to decrease exposure) or divide by

0,68 (equivalent to increase exposure or multiply by 1,47)?



Best regards,



Pawel

> Hi Pawel,

>

> You don't mention the scope you're using, but I got surprisingly

> similar values with my 8" Meade SCT and TV101 (4" apo refractor)

from > G2V calibrations:

>

> Red: 0.68

> Green: 1.00

> Blue: 0.85

>

> I.e., 1.47:1.00:1.18 RGB color or exposure weightings.

>

> Hope this gets you in the ballpark.

>

> -Marc



----------------------------

#14037 Oct 1, 2004

Hey Pawel,



If you read to the end of my message, you see where I give you the

reciprocals (i.e., 1.47, 1.00, 1.18). The first set show the relative

sensitivities (the camera's much less sensitive in red than green, for

example), the second set the relative weightings you'd (typically)

want to apply during color combinings (e.g., with MaxIm) if you shoot

the same duration subimages as you say you do. You could, instead, use

the values to shoot the proportional duration subimages and then

combine the results 1:1:1. That is, if you shot 14.7 minute reds, 10

minute greens, and 11.8 minute blues, you'd then want to color combine

1:1:1.



Hope this clarifies things.



-Marc

--- In MaxImDL@yahoogroups.com, "plancuck66" pawel.lancucki@p...> wrote:

> Marc,

>

> Thank you very much.

>

> I use Takahashi FS102 and FS60C and plan to acquire FSQ106 shortly. I

> do take RGB exposures of the same duration for the dark calibration

> simplicity (only one set of darks for the whole session).

>

> Just additional question - by "Red: 0.68" you meen that I should

> multiply R by 0,68 (equivalent to decrease exposure) or divide by

> 0,68 (equivalent to increase exposure or multiply by 1,47)?

>

> Best regards,

>

> Pawel

>

> > Hi Pawel,

> >

> > You don't mention the scope you're using, but I got surprisingly

> > similar values with my 8" Meade SCT and TV101 (4" apo refractor)

> from

> > G2V calibrations:

> >

> > Red: 0.68

> > Green: 1.00

> > Blue: 0.85

> >

> > I.e., 1.47:1.00:1.18 RGB color or exposure weightings.

> >

> > Hope this gets you in the ballpark.

> >

> > -Marc



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