Fixing Star color

[Zocky]

Shailesh, we have the same camera, only mine have FW5.
Now that you have cleaned your filters, take a few flats with each filter. Flat files are the best way to see in what condition filters are.
 

[strivedi]

Will do. Thank you very much Zocky.

Shailesh

[topboxman]

If possible, try taking flats without filters and use this as a baseline so you can differentiate between CCD window and filters.

Peter

[strivedi]

Peter,

That will mean removing one of the filters

But need to retake flats for sure. Thanks.

Shailesh

[topboxman]

Yes, but if you don't take flats without filters then you will never know which dust motes came from CCD window or filters.

Peter

[Zocky]

Yes, but if you don't take flats without filters then you will never know which dust motes came from CCD window or filters.

Peter

It is not necessary to remove the filters.
It is easily to see which dust spots are on CCD window and which are on filters. As I described above, use blinking method. Spots which are moving are on the filters, and the static ones are on the CCD window. It is very unlikely that you will have dust exactly on the same place on filter and CCD window, and due to that be unable to differentiate where it is.

[pfile]

right - since the dust on the filter is farther away from the sensor, it casts a bigger (and lighter) shadow. the smallest, darkest spots are right on the sensor.

[topboxman]

You are correct that it's not necessary to take flats without filters. After taking flats for all filters and creating Master flats for each L, R, G, & B, overlay all Master LRGB flats and you can determine which dust motes are from the filters or CCD window. If the dust motes overlay perfectly for all LRGB flats, then these dust motes are from CCD window. The rest of the dust motes are from the filters.

Peter