Re: Question about using Darks with SBIG ST-2000C


Nov 9, 2004

 


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

#14746 Nov 9, 2004

jiprovi wrote:

> I have been starting to image with the SBIG ST2000C w/AO-7 on a Celestron CGE1100

> (11" SCT) and 0.5 focal reducer (Denkmeir). I have used the BW version (ST2000)

> successfully with MaximDL in past (removing noise via dark image calibration). When I try

> to remove the noise from the ST2000C images, I notice that MaximDL is subtracting "too

> much" as the calibrated image ends up with darker pixels that can be seen in brighter

> areas of the image. The images I am removing noise from are taken as 1x1 binned and are

> converted to color via the "convert to RGB" command. The procedure I use to remove the

> noise from these color images is the following:

>

> I take a dark image at the same exposure time as the original DSO image at 1x1 binning. I

> then add this dark image via the "set calibration" dialog box. Note the image that I add as

> my dark calibrated dark has NOT been converted to color but is still monochrome. Once I

> have the dark image added to my calibration, I then bring up the 1x1 bined color image

> and apply calibration. The original image was extremely noisy and the resulting image is

> noise free except now I have these faint black pixels across my image. Can someone

> please let me know what I am doing wrong.

>

> Thanks.

> James



The calibration frames AND the image frames should be in monochrome mode

when they are calibrated. Do the Convert RGB *AFTER* you calibrate the

image.



Doug



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



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



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



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

#14769 Nov 10, 2004

Doug - clarification. Is my understanding correct in that I should

keep my dark in monochrome when I add it as a dark in my set

calibration and that I apply the dark to the monocrhome image? At

that point, I go ahead and run the "convert to RGB"?



Thanks

James



--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@c...>

wrote: > jiprovi wrote:

>

> > I have been starting to image with the SBIG ST2000C w/AO-7 on a

Celestron CGE1100 > > (11" SCT) and 0.5 focal reducer (Denkmeir). I have used the BW

version (ST2000) > > successfully with MaximDL in past (removing noise via dark image

calibration). When I try > > to remove the noise from the ST2000C images, I notice that

MaximDL is subtracting "too > > much" as the calibrated image ends up with darker pixels that

can be seen in brighter > > areas of the image. The images I am removing noise from are

taken as 1x1 binned and are > > converted to color via the "convert to RGB" command. The

procedure I use to remove the > > noise from these color images is the following:

> >

> > I take a dark image at the same exposure time as the original

DSO image at 1x1 binning. I > > then add this dark image via the "set calibration" dialog box.

Note the image that I add as > > my dark calibrated dark has NOT been converted to color but is

still monochrome. Once I > > have the dark image added to my calibration, I then bring up the

1x1 bined color image > > and apply calibration. The original image was extremely noisy

and the resulting image is > > noise free except now I have these faint black pixels across my

image. Can someone > > please let me know what I am doing wrong.

> >

> > Thanks.

> > James

>

> The calibration frames AND the image frames should be in

monochrome mode > when they are calibrated. Do the Convert RGB *AFTER* you

calibrate the > image.

>

> Doug

>

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

>

> Doug George

> dgeorge@c...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

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



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

#14770 Nov 10, 2004

James,



Yes, that's correct. Enter the mono dark frames into the "Set Cal"

dialog, calibrate the mono light frame from the camera, and only

then should you go ahead and convert the image to RGB.



Cheers,

Chris





jiprovi wrote: >

> Doug - clarification. Is my understanding correct in that I should

> keep my dark in monochrome when I add it as a dark in my set

> calibration and that I apply the dark to the monocrhome image? At

> that point, I go ahead and run the "convert to RGB"?

>

> Thanks

> James

>

> --- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@c...>

> wrote:

> > jiprovi wrote:

> >

> > > I have been starting to image with the SBIG ST2000C w/AO-7 on a

> Celestron CGE1100

> > > (11" SCT) and 0.5 focal reducer (Denkmeir). I have used the BW

> version (ST2000)

> > > successfully with MaximDL in past (removing noise via dark image

> calibration). When I try

> > > to remove the noise from the ST2000C images, I notice that

> MaximDL is subtracting "too

> > > much" as the calibrated image ends up with darker pixels that

> can be seen in brighter

> > > areas of the image. The images I am removing noise from are

> taken as 1x1 binned and are

> > > converted to color via the "convert to RGB" command. The

> procedure I use to remove the

> > > noise from these color images is the following:

> > >

> > > I take a dark image at the same exposure time as the original

> DSO image at 1x1 binning. I

> > > then add this dark image via the "set calibration" dialog box.

> Note the image that I add as

> > > my dark calibrated dark has NOT been converted to color but is

> still monochrome. Once I

> > > have the dark image added to my calibration, I then bring up the

> 1x1 bined color image

> > > and apply calibration. The original image was extremely noisy

> and the resulting image is

> > > noise free except now I have these faint black pixels across my

> image. Can someone

> > > please let me know what I am doing wrong.

> > >

> > > Thanks.

> > > James

> >

> > The calibration frames AND the image frames should be in

> monochrome mode

> > when they are calibrated. Do the Convert RGB *AFTER* you

> calibrate the

> > image.

> >

> > Doug

> >

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

> >

> > Doug George

> > dgeorge@c...

> >

> > Diffraction Limited

> > Makers of Cyanogen Imaging Products

> > www.cyanogen.com

> >

> > 25 Conover Street

> > Ottawa, Ontario,

> > Canada, K2G 4C3

> >

> > Phone: (613) 225-2732

> > Fax: (613) 225-9688

> >

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

>

>

>

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

#14777 Nov 10, 2004

jiprovi wrote:

> Doug - clarification. Is my understanding correct in that I should

> keep my dark in monochrome when I add it as a dark in my set

> calibration and that I apply the dark to the monocrhome image? At

> that point, I go ahead and run the "convert to RGB"?



Correct.



Doug



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



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



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



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

#14786 Nov 10, 2004

Thanks, Chris and Doug for clarifying. I will give it a try.



James



--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@c...>

wrote: > jiprovi wrote:

>

> > Doug - clarification. Is my understanding correct in that I

should > > keep my dark in monochrome when I add it as a dark in my set

> > calibration and that I apply the dark to the monocrhome image?

At > > that point, I go ahead and run the "convert to RGB"?

>

> Correct.

>

> Doug

>

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

>

> Doug George

> dgeorge@c...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

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



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