Quote:
Originally Posted by gregbradley
I haven't found much benefit in synthetic luminance from RGB filtered images.
I think its better to simply take more luminance.
I usually bin my RGB so it also tends to be lower resolution.
Also colour is often taken when the object has moved away from the zenith as you concentrate on getting the sharpest luminance images first unless you do luminance on one or several nights and colour on another.
There's no substitute for high QE cameras, fast optics with large aperture and good seeing with dark skies plus good tracking.
That technique was developed at a time when the typical CCD had 50% QE or less and optics tended to be slow. Its a bandaid solution.
The best images have the best basics in them that were done very well not processing trickery which always shows through like cosmetic surgery always seems to.
Greg.
|
I admit to still having an open mind on this Greg so I'm looking to test my arguments in support of synthetic luminance. I may just learn something in the process
This being the case, let me unpack your response if I may.
I haven't found much benefit in synthetic luminance from RGB filtered images.
I think its better to simply take more luminance.
I usually bin my RGB so it also tends to be lower resolution.
This is the core issue as to whether there is a quantitative benefit to be realised from the two broad options:
1. Unbinned colour with synthetic luminance; or
2. Binned colour and unbinned luminance.
I see that you advise little benefit from synthetic luminance but I would need to understand what this means. Was the luminance extracted from binned data etc? How was the result evaluated? etc.
... colour is often taken when the object has moved away from the zenith ... concentrate on getting the sharpest luminance images first ...
A good approach however I would argue that imaging in RGB whilst spreading the acquisition evenly throughout the imaging times would ensure that we have data that is subject to the same conditions.
There's no substitute for high QE cameras, fast optics with large aperture and good seeing with dark skies plus good tracking.
Well I certainly cannot argue with that logic. However, I cannot see how that point is relevant. If we are looking for a quantitative assessment of two options then we must keep the other variables consistent. Therefore, for the same equipment configuration, sky conditions, tracking etc., are we better off with RGB unbinned and a synthetic luminance?
That technique was developed at a time when the typical CCD had 50% QE or less and optics tended to be slow. Its a bandaid solution.
I assume that the words "that technique" here refer to the application of a synthetic luminance. I must admit that I haven't seen any reference to this being developed as a 'band aid solution' necessary to overcome limitations with optics and camera sensors. In fact, I would have thought that this is a technique developed over the past decade to take advantage of the improvements in camera filter technology. I would be interested in any reference material you have on this.
The best images have the best basics in them that were done very well not processing trickery which always shows through like cosmetic surgery always seems to.
I don't agree that terminology such as "processing trickery" and "cosmetic surgery" are applicable here in the context of synthetic luminance as they don't really add any value in terms of why one method would be better than the other. Either there is something that we can see and/or measure or there isn't.
I'm looking forward to a continuing discussion on the pros and cons that properly evaluates the different options. To this end I will see if I can hunt down some data where I have captured luminance as well as unbinned RGB and post them here for evaluation.
CS,
Rodney