M27 - lrgb

[Paramount]

Hi All
I managed to get out last night despite a bad boutof laryngitis (must have kept the neighbours awake with my coughing - still it gets my own back for the security lights going on and off all the time). I thought I would have a go at one of the earliest targets that I tried when I first started imaging with my Meade system 3 years ago so I aimed at M27. I wasn't sure about exposure times as this is a fairly bright planetary nebula and with the f5 of the BRC-250 I decided on 2 minute subframes of which I took 24 for luminance using a CLS filter and 15 each for RGB. No calibration was used. My earlier (and rather pathetic attempt) can be seen at the beginning of the nebulae page in the image gallery on my website http://www.imagingtheheavens.co.uk for comparsison
Thanks for looking
Best wishes
Gordon

http://www.imagingtheheavens.co.uk/U...ES/M27high.jpg

[jjjnettie (Jeanette)]

While you may look back now and think that your earlier effort isn't the best, it was the very best you'd done at that time and you were right to be proud of it.
You've come an awful long way since then as this new rendition of M27 clearly shows.
Very nice work.

[renormalised (Carl)]

Good shot Gordon...lots of detail in the neb

One way to fix the neighbours with that pesky security light....got one yourself??. Get a bigger one....1Kw globe and put it on a timer to switch on and off every 10 minutes...face it at their bedroom window!!!!

[Alchemy (Clive)]

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

[telecasterguru (Frank)]

Gordon,

You have produced a decent effort. Well done.

Frank

[Paramount]

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

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

[Alchemy (Clive)]

Originally Posted by Paramount

Hi Clive
Thanks for the comments and don't worry I welcome any suggestions that help.
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.

glad you werent put out, i agree completely that it is a combination of equipment and other skills, and not just the gear, you do have a good setup so once the processing takes its place you will get some incredible images.

now that the ice has been broken i will watch your progress with interest.

cheers clive.

[Paramount]

Hi
Following some suggestions I have reprocessed this imagewith particular respect to sharpening and the background noise, I have reduced both although there is still a bit of noise evident it is not as bad and to get rid of it completely would have meant an artfificially smooth image, more subframes will be needed to improve it further, thanks for looking
Best wishes
Gordon

http://www.imagingtheheavens.co.uk/U...umbellhigh.jpg

[renormalised (Carl)]

Now, that 2nd image looks real good..better than the first

[multiweb (Marc)]

Much nicer yes. Like the repro better than the original. Still a bit harsh IMHO. Dark skies and bit clipped on the stars but the details in the neb are beautiful.

[strongmanmike (Michael)]

Ah yes! Quite nice Gordon

Mike

[marc4darkskies (Marcus)]

The repro nailed it Gordon - nice one!

Cheers, Marcus

[bloodhound31]

Yup! Like the repro!

Baz.