Learning DSS astrophotography but can not get any nebula developed... Any help would be appreciated.

[UberStar]

Hi all

 

I am very new to astrophotography and the best i have done before is a nice shot of orion nebula but thats quite easy for a newcomer i think.

 

Trying to move onto other nebula and have tried numerious times to get the heart and soul nebula but each time i try to develop through Sequator then PS or Pixinsight i am not bringing any red out whatsoever and i am stumped as to why ?

 

I am using a Nikon D750 unmodded and tried various lenses even going down to 50mm prime lens that i 100% know i am getting the nebula im my images as double checking through Stellarium and all the stars match up but like i say i get no nebula im my images.

 

My settings are 20 seocnd exposures on a star adventurer pro tracker. If i go any longer than 20 seconds i find my images look washed out like the exposure is too high. I am shooting on F3.2 with around 400 ISO.

 

Im n a 5 Bortle in cheshire area of the UK.

 

Do i need light polution filters, longer exposures and higher F stop with lower ISO ?  Or is it simply i need to get under darker skys ? I really dont want to spend out £200 on clip in filters if i can help it if i can get away with changing a few settings or if someone has some wise advise for a beginner please ?

[dannybgoode]

For most nebulae you need exposure times in the minutes not seconds. When you say the images are washed out if you expose for longer than 20” what are you viewing them in? Are they auto-stretched etc?

What are your other camera settings? RAW or jpeg, are you definitely in full manual mode etc?

 

[UberStar]

1 minute ago, dannybgoode said:

For most nebulae you need exposure times in the minutes not seconds. When you say the images are washed out if you expose for longer than 20” what are you viewing them in? Are they auto-stretched etc?

What are your other camera settings? RAW or jpeg, are you definitely in full manual mode etc?

 

Hi Danny

 

Im in RAW+Fine

 

The images are just viewed through the camera after taking the images, the sky just looks too bright, i think its maybe a little light polution but have seen others taking nebula images through light polution in as higher and higher bortles than im in.

 

I guess i should maybe up the F number to 4 or 5 and aim for around a 90secondds to 2mins and decrease my iso to around 200 and then try to auto strecth through Pixinsight ?

[dannybgoode]

6 minutes ago, UberStar said:

Hi Danny

 

Im in RAW+Fine

 

The images are just viewed through the camera after taking the images, the sky just looks too bright, i think its maybe a little light polution but have seen others taking nebula images through light polution in as higher and higher bortles than im in.

 

I guess i should maybe up the F number to 4 or 5 and aim for around a 90secondds to 2mins and decrease my iso to around 200 and then try to auto strecth through Pixinsight ?

My skies are Bortle 8/9 and even images minutes long are not too bright. You need to view the un-stretched RAW images on your computer though. Your camera, even shooting in RAW does some processing to show the images on the screen though this processing is not carried through to the file.

You should be aiming for at least 2 mins at ISO 800 or 1600 but don’t judge the results until you’ve viewed them unstretched on the computer

Take a single test shot if you don’t want to potentially waste a load of time taking frames that end up being useless. 

[UberStar]

Thank you

 

Hoping for an hour tonight so i'll try what you say and hopefully have results soon.

[UberStar]

Just took an untracked image from my back door for 90 seconds on D750 on 50mm lens at F3.5 and ISO at 620 and you can see how bright the sky looks its almost like a blue sky,  the WB is set to auto mind you but i think this is stilla little bright to capture nebula ?

 

 

750_5287.NEF

[Clarkey]

I just had a quick look at your above image and it definitely appears to be stretched. It was also taken quite early, so the sky would not have been fully dark. I'm not a Nikon user so I do not know if there are any other formats you can use as this definitely does not seem to be raw data. I live in a Bortle 6 area and I can 3 minutes or more in RGB without issues providing the moon is not messing things up! Putting it through AF I managed to remove the gradients and put some of the stars back along with realigning the RGB channels. This then appeared to be more like the expected result.

As for why it is doing it - best ask a Nikon owner!

[Erling G-P]

When you say you get no red at all with the nebulae, are you talking about single subs or stacks of several images ?

Even with a modded camera, I get only very faint traces of red on single 3-minute exposures at ISO 800 of the Soul Nebula, with a SW 130PDS scope

[rickwayne]

Especially for dim emission nebulae, and looking through the built-in IR cut filter on your Nikon, the image preview gives you little useful data for judging exposure. Far better to go by the histogram, and the good news is that the  rules aren't too subtle.

Dim as it is, the nebula is going to be brighter than the background, which makes up most of the pixels in your image. So if the big peak is completely clear of the left edge, you  won't  be black-clipping anything. With stacking, that is actually enough right there.  You can check for overexposure too, the histogram's tail shouldn't actually touch the right side either. If  you  can't satisfy both,  that means the  scene has more dynamic range than your camera can accommodate, so you  have  to either allow some black clipping, blow the brightest elements (stars) out to white, or resort  to HDR techniques of shooting and combining  exposures optimized for each end of the range. The Orion Nebula is notorious for this -- lots of very dim gas, but the Trapezium area is  super-bright.

[rickwayne]

Oh, two other tidbits:  For an unmodded terrestrial camera and a dim emission nebula, take LOTS of sub-exposures. You'll want hours of total integration time for the best results, which for 20-second subs means hundreds of frames. Yes, you're right, that will  be a complete PITA to process, which is one big reason why the true obsessives spend kilobucks on mounts  that allow 10- or 20-minute exposures.

Also, you can use plate solving to really nail down where you're pointing. With Internet access, upload a JPG or FITS to nova.astrometry.net, within a  few minutes you will have an exact  solution. You can also download ASTAP, or PlateSolve2, or the offline version of astrometry.net, plus the data files, to do the same thing local  to your computer.

[UberStar]

Hi guys thank you for the replies

 

I have finally got the horse head nebula after quite some time and in a bortle 4, i will continue with the advice given by you all and hopefully on the next  clear night will have some results.