Ngc 6744

[phobos27]

This is a mediocre image I captured of NGC6744 from surburban Brisbane last night. It is 367 images at 30 seconds each stacked in DSS. 3 hours 30 minutes all up. I forgot to do dark frames and this may have affected the final result.

I can not seem to get any colour out of this image? Is it my editing skills in light room or is it DSS or just the fact that there is very little colour in this image?

Would love some feedback!:)

[cometcatcher]

Lots of detail there! But not much colour. Did you process in DSS or other software? DSS does tend to desaturate the image the more subs you stack. The colour has to be encouraged back in.

[phobos27]

Thanks for that! I did stack the photos in DSS but took the image straight out afterwards. I processed it in Lightroom 5 after that. What other software could I use to stack and or process my images to yield better results? Or is there a more advanced tutorial for processing images in these program's?

Thanks for the feedback!

[Tony_]

Hello Nick,

This doesn't look like 3.5 hours of data. Either something has gone wrong during DSS stacking or post processing. It looks like there is no colour at all and you have darkened the background too much.
I suggest you reset DSS to default settings then restack your data. Go to saturation and increase it to about 14% (you don't have to do this but it will increase the colour a bit). Then go to RGB/K levels and use the left sliders to bring the colour peaks down to where the histogram drops off (about half way) and all peaks to the same point - this will balance the colour a bit. You can play with these levels until the image looks reasonably balanced. Don't make it too dark - you can fix this later.

Your image should look better already. Then save it and do post processing. Photoshop is good (but expensive) or you can use a free software (google and download) called GIMP. It isn't as good as photoshop but it is free and has similar features. There are other software available Pixinsights is popular.

Good luck - I'm happy to help more once you have a better image to work with. I'm no expert but I can help a bit.

Regards,
Tony.

[phobos27]

I know this is probably quite obvious but how do you reset your settings on DSS? I do have Photoshop but will have to experiment with it a little to see what I can get out of it as i have never adjusted astrophotos in it before. I will run the stacking process again tonight and see what results I can yield.

Thanks for the help. I have been meaning to ask some of these questions as i really have no idea what i am doing! If anyone know of any good tutorials using this program it would be great as I have not found any decent ones yet.

[Tony_]

Options - Load - restore default settings - save.

Once you have restacked the image post what comes out of dss before you process it.

[phobos27]

Here is the image straight out of DSS. I have also added the edited photo out of DSS, no processing in Photoshop yet. (Green one is straight out of DSS)

[Tony_]

Doesn't seem to be much data there - looks like a single sub? Are you sure DSS stacked all the images? It should have registered them all first and then stacked them - it should have taken about 20 minutes or so?
Sometimes if there is a problem you will get the message that it only stacked 1 image.
Did you actually see the stacking process? It will give a progress count. eg. stacking image 150 of 300 etc.

[phobos27]

Yes it was definitely stacking all 300 subs. It took about 40 minutes. It might be because my exposures were 30 seconds long? I don't know. I am still trying to get my head around using this program.

My previous image looked like that when it came out of DSS. Is it because I do not have any dark frames, flat frames it bias frames?

Thank you so much for your help!

Nick

[cometcatcher]

Out of curiosity can I have a look at a single sub before DSS and with no processing?

[Tony_]

I'll help again tomorrow- there is something wrong with your stacked image.
It really shouldn't look like that. It doesn't look like a stacked image at all.
I often take only 30 sec subs and my stacked image never looks like that - even when I only have 40 minutes of data. Post one of the subs straight from the camera with no processing.
The darks help reduce noise - but it won't affect the image like this.

What camera / telescope are you using?
What were your camera settings?

[phobos27]

I have posted a single sub no editing.



I am using a Nikon D-7100 on an AZ-EQ6 with a 8 inch dob. However it is 200mm*800mm. F/4. My camera settings were 30 second exposures, ISO 1250 and White Balance at 4000K. I was also taking Raw images. No different from what i normally do... My profile pick used the same settings (except ISO 1600) so I don't know what is wrong.

Thank you so much for all of your help. It will be great to get this sorted out!

Nick

[cometcatcher]

Your single frame looks fine. From memory, DSS would do strange things to some RAW formats. What are your RAW options in camera? Does your Nikon have DNG and / or NEF? I had trouble with my Pentax using PEF and had to change to DNG.

[phobos27]

My camera can only shoot in NEF... I will convert my images to DNG and retry processing... Might take a while.

[phobos27]

After so many hours it is finally done (need a new computer!) and I now have two new versions of the photo. Both have come from DNG format subs and it seems to have produced a much better result.

The first image is what DSS gave to me without any editing with the DNG file.
The second photo was my go at editing that in Lightroom. Worked quite well, even getting some colour.
The next photo is after adding 14% saturation and adjusting the histogram a little bit.
The final photo is a edited version of that!

Thank you guys for all your help. I am so glad i could get this photo sorted out because it seemed like quite an interesting target!

Let me know which of the two photos you think is better!

Regards Nick

[cometcatcher]

Well done on getting more colour! I like the last one.

There is probably still a setting in DSS specific for Nikon in the settings. You may have to experiment to see what works.

[phobos27]

Thank you Kevin for all your help and for the feedback! What do you mean by the fact that there might be a specific setting in DSS for Nikon? Do you mean for processing the NEF photos straight out of the camera? Sorry for all the questions...

Nick

[phobos27]

Never mind. Got it. I just needed to download the latest version of DSS. I thought my camera was already supported because i had been getting some good photos over the last few months.

Despite that it was still great to get an idea of what all this actually is!

Sorry for any trouble!

Nick

[Tony_]

Much better! The galaxy itself looks much better, although your stacked image looks very dark compared to the sub? The histogram is too far to the left which makes the background too dark and the stars too bright. I don't know what is wrong - but I suspect there is still something not quite right happening in DSS.

It's not a particularly easy galaxy to image. The nucleus is fairly bright but the arms are fairly faint - especially the finer detail.

Regards,
Tony.

[cometcatcher]

DSS does the same thing to me - the stack is much darker than an individual sub. There is an adjustment for that also, but in the end it doesn't make much difference to the image when stretched so I just leave it.

[phobos27]

Thanks Tony! The Sub is always darker like Kevin said. So hopefully that is the problem. I am happy with the result I have gotten so I will just leave it!



Thank you both for all your help and for staying with me. It has been an experience to say the least. Might try this again in the future and we will see what we get then!

Regards
Nick

[Tony_]

My first 6744 looked a lot worse than this. My more recent one was better - but no-where near enough exposure time.
Did you use flats for this image? When I started I never used flats - I just processed out the vignetting, but flats make a huge difference. It will give a much more even background and will enable you to bring out more detail.

My images are still quite humble compared to the ones posted here - but I still enjoy it as long as the image resembles the object without too much noise and horrible stars.

[phobos27]

Thanks Tony. I only took light frames for this photo because I forgot to do anything else. I have actually never tried taking flat or bias frames, only dark because I do not know how to take them. Might try this again next time.

Nick