First try at the Iris Nebula

[Quatermass]

After imaging M100 I was getting the urge to have a go at the Iris Nebula for a change from galaxy's, despite it getting very late it was coming around into position for a shot at it so burned the midnight oil a bit longer and had a crack at it.

I managed to get 40 subs at just under 2 mins each. All the street lights had gone out and the neighbours all gone to bed so it was nice and dark.

Set to work on it this morning and this was what I came up with, here is the stacked and final processed image for comparison.

40 2 min subs stacked with 30 darks flats and bias this is the stacked image

And after processing

[Shibby]

Hi Mark, looks like you have captured some nice details there. But also looks like you've struggled with the colour balance. I can't recommend enough the RGB background calibration setting in DSS, particularly for those of use with light pollution. All that nebulosity should be nice and blue, I bet you'll see that as soon as you try out the RGB calibration!

[Quatermass]

The RGB calibration.. do you mean shifting the red green and blue graphs into one area after its stacked?

[Shibby]

Yeah, DSS can do this for you. It will calibrate the 3 histograms to each other and then shift them to the same place - should work well on this nebula.

[Gina]

Yeah, DSS can do this for you. It will calibrate the 3 histograms to each other and then shift them to the same place - should work well on this nebula.

Oh, can it? I've always done this by hand

[Quatermass]

I am now giving that a try in DSS to see if it makes a difference having just read this in the yahoo groups.

Hi all,

I work with a Canon 350D with IR filter completely removed.

For similar equipment I definitely recommend RGB channel calibration.

Infact R channel results overexposed compared to B anf G channels and this is

relatively difficult (and sometimes impossible) to recover during post

processing.

Bye

Rosario

astromaster

----- Original Message -----

From: Luc Coiffier

To: DeepSkyStacker@yahoogroups.com

Sent: Monday, November 24, 2008 8:20 AM

Subject: [DeepSkyStacker] Re: Per Channel Background Calibration vs RGB

Channels Calibration

[Quatermass]

Oh, can it? I've always done this by hand

Yes me too will post the results when its done have had 5 power cuts here in the last 3 hours and my imaging laptop has crashed big time and having a new reinstall what a pig! grrrr

[Quatermass]

mmm did not get a good result using rgb background calibration it left me with hardly any colour at all to work with and was washed out and gray?

[Gina]

Sounds bad Mark Hope you get everything sorted out soon We've been having dreadful weather - several inches of rain in the last couple of days and gale to storm force winds. A large pane of glass was sucked out of the sun lounge, fortunately falling on the grass which has shot up in the last few days cushioning the glass and it didn't break. No sign of any clear nights till at least next week! Have some odd jobs to do on the equipment though so not entirely lost time.

Re. DSS - I can't find where you can align the RGB histograms in one stroke.

[Quatermass]

Tell me about it Gina today really sucks.. my dell laptop hard drive has crashed but mercifully I had everything backed up. The weather is really horrible gray and wet and deee pressing I tried to re stack this image several times and the powercuts just messed it all up again sigh. Some days are just like that I guess.

Im sure that having more subs for this would really bring out the colours but I dont have enough of them for this one and its needs a guided set of subs with longer exposures for really good results but I am quite happy to have found it and had a first try.

To change the setting in DSS look in the recommendations section when your ready to stack and you will see it there, your stacking steps will say RGB channel background calibration:yes and per channel background calibration: no if you have set it correctly if not go back to the recommendations and change it there.

Lets hope this rotten weather clears up and we get some sunshine and clear skys soon.

[Digz]

mmm did not get a good result using rgb background calibration it left me with hardly any colour at all to work with and was washed out and gray?

I've had the same experience here trying that. Give a manual calibration in DSS by aligning the RGB peak and let's see it.

Great looking start BTW, don't think my D7000 would far as well.

[Quatermass]

I've had the same experience here trying that. Give a manual calibration in DSS by aligning the RGB peak and let's see it.

Great looking start BTW, don't think my D7000 would far as well.

Thats what I did with this first try, I stacked the image then moved the rgb channels in line manually and adjusted the stacked tiff in Photoshop. It does say in the dss manual to change it to per channel calibration if the resulting images are too gray.

Too be honest I think having too few subs on this one is the issue and it needs to be guided for longer exposures to do it justice.

I always get excited when I am looking for something up there that I've not seen before and when it came into my view it was a real buzz to see for the first time.

[Digz]

I'd love to give this a try, too much drought around at the moment

As for grey images out if DSS I've always had this. It take serious tweaking of the curve in DSS. Lately I've been taking the stacked tiff into my trial of PI and using the STF - works wonders.

[Gina]

Im sure that having more subs for this would really bring out the colours but I dont have enough of them for this one and its needs a guided set of subs with longer exposures for really good results but I am quite happy to have found it and had a first try.

Yes, difficult to get a lot of data these days - my M51 needs more data, I'm sure that's the main problem with it. I'm not sure lowering the dark noise has done much.

To change the setting in DSS look in the recommendations section when your ready to stack and you will see it there, your stacking steps will say RGB channel background calibration:yes and per channel background calibration: no if you have set it correctly if not go back to the recommendations and change it there.

Ah yes, thanks I've just set DSS to repeat the stacking and gone through the recommended settings and set everything to the recommendations including the RGB channel background calibration. So will see what this gives.

Lets hope this rotten weather clears up and we get some sunshine and clear skys soon.

Goodness me, yes!!!!!!!

[Quatermass]

I'd love to give this a try, too much drought around at the moment

As for grey images out if DSS I've always had this. It take serious tweaking of the curve in DSS. Lately I've been taking the stacked tiff into my trial of PI and using the STF - works wonders.

What is PI and STF:confused:

[Digz]

Sorry dude, PI is PixInsight. It has a great tool to stretch data called Screen Transfer Function. Not a free piece of software but you get a 45 day trial and I must say its looking like its gonna be worth the money.

[Quatermass]

Ah I see.. I use Photoshop all the time have been using ever since I can remember and started using it when I was designing game models for unreal tournament many moons ago.

[RikM]

QM do you save the DSS output with settings applied? I always use the 'save with settings embedded but not applied'. When you open the file in Photoshop you just see a black square, but you then have much more control over how the images is stretched and colour balanced.

If you want to have quick look in DSS, either use RGB backgound calibrate or per channel calibration and then align the peaks manually (I do it the second way), then on the saturation tab, increase it to 15 - 20 % and hit apply. This will bring the colour back, but you should really only treat it as a preview. Save the image wit settings embedded but not applied and get a better starting point for working with it in Photoshop.

[Digz]

QM do you save the DSS output with settings applied? I always use the 'save with settings embedded but not applied'. When you open the file in Photoshop you just see a black square, but you then have much more control over how the images is stretched and colour balanced.

If you want to have quick look in DSS, either use RGB backgound calibrate or per channel calibration and then align the peaks manually (I do it the second way), then on the saturation tab, increase it to 15 - 20 % and hit apply. This will bring the colour back, but you should really only treat it as a preview. Save the image wit settings embedded but not applied and get a better starting point for working with it in Photoshop.

I've tried this on several occasions but can never get anything decent when trying to edit in PS. I think it opens in PS as a 32bit which is limited in using adjustment layers IIRC, I must be doing something wrong but don't know what

[Quatermass]

I'm now stacking a second batch so will give all that I try Rik many thanks for pointing that out. Its so grotty and wet out side its nice to be doing some processing currently stacking up my M100 to see how that comes out. Will post it when its done with some notes on the dss settings. Cheers

who is Tarquin?? and why do you both love him?

[Digz]

Looking forward to seeing what happens. Tarquin is the new Steve

[RikM]

I've tried this on several occasions but can never get anything decent when trying to edit in PS. I think it opens in PS as a 32bit which is limited in using adjustment layers IIRC, I must be doing something wrong but don't know what

Go into mode and change it to 16bit tiff then everything should work. I save as 16bit tiff direct from DSS.

[Quatermass]

Looking forward to seeing what happens. Tarquin is the new Steve

Ah now I understand lol so many Steves about it had to happen

[Digz]

Go into mode and change it to 16bit tiff then everything should work. I save as 16bit tiff direct from DSS.

Ah yeah, but what option do you select when converting?exposure and Gamma? Does any data get lost in the conversion? Looks like it might be time for a play.....

[Quatermass]

Ah yes that's better Rik. I just stacked my M100 and moved the RGB channels in line and tweaked the curve a bit then after doing that moved the saturation shift up to 15% that made a big difference in getting the colour back on the galaxy that was bland and gray before hand. Now going to have to restack it all as I forgot to take out the frames with satellite trails doh!