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Are seperate flats needed for each filter when doing LRBG?

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#1 Surfer4329

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Posted 12 November 2019 - 09:28 AM

I am debating on buying 1600MM Pro, but the whole LRGB thing seems like a deeper rabbit hole in an already lengthy process compared to one shot color imaging. I'm assuming I can use a master dark and a master bias but I'm assuming flats need to be taken for each LRGB filter. I'm considering the 183MC Pro instead of the 1600MM Pro because of the one shot capability. There would be slight oversampling with my focal length of scope, but maybe binning could help if it becomes an issue on certain targets?
 


Edited by Surfer4329, 12 November 2019 - 09:28 AM.


#2 AZ Maverick

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Posted 12 November 2019 - 09:50 AM

Yes, separate flats are required for each filter.

You never know what sort of dust motes and such are sitting on each filter.

But with today's imaging programs taking flats is an automated task that is extremely quick and easy and takes less time than taking the darks.


Edited by AZ Maverick, 12 November 2019 - 09:51 AM.


#3 Gipht

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Posted 12 November 2019 - 10:24 AM

if you are considering the ASI183MC in tandem with a longer focal length telescope, you will  want to consider the size of the targets you want to image.   The field of view will be fairly limited.  So far I have not been that impressed with RGB imaging of smaller targets with my 1000mm focal length reflector and the 183MM-c pro camera.  The star size is difficult to control.  Narrow band imaging with the 183MM-c has worked very well.

 

As Az Maverick pointed out taking flats for each filter is not at all time consuming.   R,G,B, H-alpha, and OIII flats can all be taken in about 5-10 minutes.

 

There is a learning curve to using a mono camera and filter wheel, and some additional time in changing filters and checking focus with each filter.  The processing  can also be more time consuming as you are using at least three different images to form the final image and have more options available. 



#4 bignerdguy

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Posted 12 November 2019 - 10:25 AM

Yes, flats for each are required as was previously mentioned the dust on each will be different.  When doing the LRGB images Binning absolutely helps with the images.  Bin the RGB at 2x2 or higher and do the L Binned 1x1. Then expand the Binned RGB images to full size when you combine them.  This way the Luminance image will have the details and the Binned images will have the brightness giving you a really cool effect which will make the details pop!


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