Quote:
Originally Posted by silv
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while "20 years" is not "new-ish"
and the fact that these are stacked and post-processed images from long exposures do not meet my criteria ..
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You have to understand what simple processing (stacking) does to a picture:
1) it reduces the noise introduced by camera
2) it reduces the effects of the atmospheric turbulence
3) it does not affect much the local visibility (LP, transparency and so on)
4) it does not affect the optical operformance of the system
Also, you will find (in time) that 20 years or even 50 does not mean much when optical design is concerned - APO from 20 years ago is very similar if not the same performance-wise to APO design done with the help of all that high performance computer software from today - because it uses the same mathematical solutions, that were done 100 year ago, and it uses the same glass materials...
The difference from 20 years ago and today is, today the design of optical systems is faster (because it runs on computers.. 20-30 years ago it was done on a piece of paper with the help of slide rule and pencil and book with logarithmic tables) and manufacturing is today somewhat cheaper. But the assembling and testing is not - it is still done manually and individually for each product.
Also, some new exotic optical materials are available today that were not on the market 50-100 years ago, but optical elements made of those materials are still very expensive, and most likely not affordable by most (myself included).
So, reasonably processed images will show you what you want and need to know - is APO better than achromat and by how much.
Kevin's images (post #39 of this thread) are exactly what you needed - side by side picture of the same object (star-like) and there you can see chromatic aberration of the achromat at work.