Does A Mono CCD Take More Time?
One of the frequent statements I see people make is that they will probably go with a One Shot Color (OSC) camera because they don't have much imaging time. This sentiment is unfortunate because it is actually exactly wrong. A mono CCD used correctly can get a equivalent image in no more time than a OSC CCD.
Here is a quick explanation.
Say you take 2 hours of data with a DSLR or OSC. What you really have done is take:
120/4 = 30m of Red data
120/4 = 30m of Blue data
120/2 = 60m of Green data
This is because of the Bayer matrix.
Say you took it as 5m exposures.
Just take
6 exposures of Red data at 5m
6 exposures of Blue data at 5m
12 exposures of Green data at 5m
and you will have close to the same quality image.
Actually, in this case you would probably want to drop to 3m exposures so you get 10, 10, and 20 exposures to take advantage of better stacking methods like Winsorized sigma clipping. (In Practice people will just shoot each color equally).
You will actually gather more data with the mono camera in the same amount of time because most mono cameras are considerably more quantum efficient than there color counterparts.
The above way of splitting things up will equal or surpass the OSC or DSLR camera. However, if you have more time say 4 hours, then what you do is spend the 1st two hours as above. Then you switch over to shooting Luminosity data. Then you will gather considerably more photons in the same amount of time compared to the color camera. That is because the filters in the OSC camera are blocking about two out of every three photons! When shooting L with the mono camera, you are letting them all through.
There are some advantages to OSC but time needed is not one of them. They are typically cheaper, they tend to have a smaller form factor which is very handy for Hyperstar, and processing may be slightly more familiar at first.
Here are some example shots using a mono CCD with limited time (3 hours or less). These are ordered from most to least time.
One of the frequent statements I see people make is that they will probably go with a One Shot Color (OSC) camera because they don't have much imaging time. This sentiment is unfortunate because it is actually exactly wrong. A mono CCD used correctly can get a equivalent image in no more time than a OSC CCD.
Here is a quick explanation.
Say you take 2 hours of data with a DSLR or OSC. What you really have done is take:
120/4 = 30m of Red data
120/4 = 30m of Blue data
120/2 = 60m of Green data
This is because of the Bayer matrix.
Say you took it as 5m exposures.
Just take
6 exposures of Red data at 5m
6 exposures of Blue data at 5m
12 exposures of Green data at 5m
and you will have close to the same quality image.
Actually, in this case you would probably want to drop to 3m exposures so you get 10, 10, and 20 exposures to take advantage of better stacking methods like Winsorized sigma clipping. (In Practice people will just shoot each color equally).
You will actually gather more data with the mono camera in the same amount of time because most mono cameras are considerably more quantum efficient than there color counterparts.
The above way of splitting things up will equal or surpass the OSC or DSLR camera. However, if you have more time say 4 hours, then what you do is spend the 1st two hours as above. Then you switch over to shooting Luminosity data. Then you will gather considerably more photons in the same amount of time compared to the color camera. That is because the filters in the OSC camera are blocking about two out of every three photons! When shooting L with the mono camera, you are letting them all through.
There are some advantages to OSC but time needed is not one of them. They are typically cheaper, they tend to have a smaller form factor which is very handy for Hyperstar, and processing may be slightly more familiar at first.
Here are some example shots using a mono CCD with limited time (3 hours or less). These are ordered from most to least time.