Quote:
Originally Posted by Alchemy
hello gordon
i see you have a lot of high end equipment which should give stunning results, there are a couple of things noticable in this image
i comment in the hope that they are taken as helpfull rather than criticism.
The stars have dark haloes around them, this is usually indicative of a sharpening process which has gone too far. If you are trying to sharpen the nebula then layer the unsharpened over the top and paint in using a layer mask the unsharpened stars, or layer the sharpened over the top and paint in the neb (my prefferred) treat the image as the sum of parts rather than applying a technique to the whole image. you might try some other techniques such as deconvolution again with the overdoing in mind. ( i dont think you used decon on this as usually it burns the star centres out noticably)
The background is a little noisy, this is usually a result of pushing the image to and beyond its limit, some noise is acceptable and this isnt horrid, however if you are trying to present the best image, then either process it less or collect more data, another technique for cutting down the background noise is to get a less processed image and layer it over the processed one, this time you need to apply a curve to darken the background of the highly processed one and as long as the less processd one has a brighter sky, blend as lighten.... this is fairly tricky to get just right and will take some practice. otherwise more data, the difference between 2hrs and 8hrs is huge
im not particularly familiar with the Scope you are using, but i asume F5 is not its native length, if so and its a bright target then given the gear you have you should get in closer for more detail.
again these comments are not intended to be critical, but to point out how you can improve what you have already achieved.
kind regards
clive
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Hi Clive
Thanks for the comments and don't worry I welcome any suggestions that help. Regarding the image, you are quite correct in the two main points that there is some over sharpening, this is something that somebody else had mentioned elsewhere, also the background is a bit noisy due to a combination of not enough data and over processing. I will be having another go at processing this image with those two points in mind as I have some idea where I over did it. I will post the reprocess here. Mind you I do plan on doing this object again but with a lot more than 15 subframes per channel. I didn't use deconvolution on this as it is something I have never really bothered with but I will have an experiment with it.
The Takahashi BRC-250 which is one of my main imaging scopes is a RC scope which is f8 in its raw format but it comes with a built in Baker field flattener/focal reducer which brings the f ratio down to f5. I have read somewhere that the reducer can be taken out but I am not sure as to the effect on the performance so I am not going to mess about with that, it is 1256mm focal length with a 10" aperture so the image posted is full frame for a Starlight Xpress H9.
The only point that I don't necessarily agree with is the equipment I use in that I agree that it is superb equipment but my level of expertise is not sufficient yet to get the very best out of it, but as I continue to learn I am sure that will come. The point I am trying to make is that it is the person taking the picture and processing it that makes the fantastic picture not the equipment, although the equipment helps and can make the whole experience easier and more enjoyable. My main reason for buying this setup was that I used to own a set up all made by one manufacturer and everything that could go wrong with it did go wrong, so as I was in a position to be able to afford it I decided to go for the best that I could afford (luckily I don't drive, don't have children and am in a well paid secure job).
Lastly I don't mind about any comments or criticism as without such comments from people like yourself people won't learn or improve so thanks again
Best wishes
Gordon
