Am I heading in the right direction with PP ?

[DarkKnight]

Hi,

I eventually got all the bits together to mount my Nikon D800 to my upgraded EQ6. Now all I need is a laptop for guiding.

In the meantime I've been trying to get my head around the basics of PP, a black art if ever there was one.

The below shots are a SOOC 'before', and an attempt at PP 'after'.

This was a single take with a 14mm Samyang, ISO4000, f2.8 at 30sec. Now I've learnt in the meantime that I need to do multiple takes, much lower ISO, and stacking. In this shot I realise that I was over the limit at 30secs as the stars were starting to trail.

This was taken out of town on a fairly clear night, except for some low hazy cloud on the horizon and some light pollution. Most of the PP I did was on exposure levels and I gave up on trying to remove the cast from the lower part of the sky.

In my inexperience I don't really know what the finished image should look like, so any comments or PP tricks most appreciated.

 

 

 

[Ishan Mair]

Wow !! Right track. The gradient in the lower right might be due to LP.

 

[wxsatuser]

You got rid of the LP ok, overall not to bad.
Think with your camera you could stick with the high ISO until you get guiding.

This what it should look like, the colourful Rho Ophiuchus is lefthandside just above centre in your image.
Stack a few and you will have a nice image

http://www.astrophoto.com/JonTalbotandMilkyWay.htm

[DarkKnight]

7 hours ago, Ishan Mair said:

Wow !! Right track. The gradient in the lower right might be due to LP.

 

Thanks for looking in.  There was a bit of hazy cloud that was picking up the light.

[DarkKnight]

5 hours ago, wxsatuser said:

You got rid of the LP ok, overall not to bad.
Think with your camera you could stick with the high ISO until you get guiding.

This what it should look like, the colourful Rho Ophiuchus is lefthandside just above centre in your image.
Stack a few and you will have a nice image

http://www.astrophoto.com/JonTalbotandMilkyWay.htm

Cheers Mike.

I was surprised with what I could get out of the shot. I've been looking at the NASA website as I figured they should have a fair idea, but as we both know, no two shots will be the same with different seeing, LP, PP etc.

There was quite a bit of recoverable red in the bright segment in the bottom LH corner but as it looked a bit odd, I didn't bring it out.

Thanks for the helpful comments.

 

[wxsatuser]

The Milky Way has brown/orange dust with blacks and of course emission regions.

You can make it what you like but those are the natural colours.
In widefield shots you may also pickup airglow, reds and greens.

Roger Clark has a good page which will give you an idea.

http://www.clarkvision.com/articles/color.of.the.night.sky/

[DarkKnight]

Great link. What a good read. I assume this guy knows what he is talking about.

Thanks Mike.

[ollypenrice]

I think you've done very well.

One thing to do regularly during post processing is check your background sky values using (in Ps) the Eyedropper colour sampler tool. I aim to end up with 23/23/23 per channel for genuine backgroud sky. It will be higher than this till right at the end but approximate colour parity is good to have.

Olly

[wxsatuser]

1 hour ago, DarkKnight said:

Great link. What a good read. I assume this guy knows what he is talking about.

Thanks Mike.

http://www.clarkvision.com/rnc/index.html

[DarkKnight]

10 hours ago, ollypenrice said:

I think you've done very well.

One thing to do regularly during post processing is check your background sky values using (in Ps) the Eyedropper colour sampler tool. I aim to end up with 23/23/23 per channel for genuine backgroud sky. It will be higher than this till right at the end but approximate colour parity is good to have.

Olly

Thanks for the tip Olly. 

[DarkKnight]

9 hours ago, wxsatuser said:

http://www.clarkvision.com/rnc/index.html

Cheers Mike.

He seems fairly well credentialed.  

I've only had a quick look at his page but there were a couple of things that caught my attention. The first was his statement that he lets his Canon 1D Mk IV do his darks in-camera. I've found that my D800 is not all that good at noise suppression so I have it turned off, and keep my ISO at 800 or lower, as the camera, by default, will take darks at ISO1600 or higher.

The other was his post on clear aperture.

Quote

Clear aperture is key to recording stars (meteors too).

I guess this chart would have to be used in conjunction with a lens known 'sweet spot'. It's about 1/2 way down on this page .......  http://www.clarkvision.com/articles/nightscapes/

It's said the proof of the pudding is in the eating and some of his photos are mind blowing for a DSLR.

I'm looking forward to having a good read of his very helpful hints.

[ChrisLX200]

10 hours ago, wxsatuser said:

http://www.clarkvision.com/rnc/index.html

You assume wrong, that guy is full of it...  http://forum.startools.org/viewtopic.php?f=4&t=912

ChrisH

[DarkKnight]

8 hours ago, ChrisLX200 said:

You assume wrong, that guy is full of it...  http://forum.startools.org/viewtopic.php?f=4&t=912

ChrisH

Thanks.

I tend not to take others ideas as gospel but rather to assess them, and if I think they hold water, pick out the bits that I may find useful.

[Astrosurf]

That's a gorgeous shot, and great for a single sub and high ISO! It'll be wonderful when stacked with several shots. What PP software did you use?

Out of curiosity, how do you find the Samyang? I hope to get the same one.

 

Alexxx

[DarkKnight]

25 minutes ago, Astrosurf said:

That's a gorgeous shot, and great for a single sub and high ISO! It'll be wonderful when stacked with several shots. What PP software did you use?

Out of curiosity, how do you find the Samyang? I hope to get the same one.

 

Alexxx

Many thanks for the kind words Alexx.

The PP was done with Adobe CC and most of it in levels, with a bit of a fiddle in Selective Colour, although as I said above I really didn't know what I should finish up with. The Gamma Correction slider, at least in my inexperience, seems like a very useful tool too.

I'm very happy with the Samyang 14mm as it seems fairly sharp right across the frame and stacked up very well against some very expensive opposition in the various online lab test results I looked at. Focusing is a bit fiddly as the infinity marker is way off, so I mainly focus using magnified live view. Unfortunately it doesn't have a filter thread so you can't use a Bahtinov Focus Mask. And like all UWA lens it has some distortion but I've done some architectural work with it and it corrected fairly well.

In general I'd give it a 

[Astrosurf]

Thanks Kev! And you're welcome. I also tend to use a lot of Levels and Curves. And yes, Selective Colour is very good. I haven't used the  Gamma Correction slider. I'll have to try that out.

Where's the distortion on the lens? The periphery? Can stopping down a little help with that?

[DarkKnight]

7 hours ago, Astrosurf said:

Where's the distortion on the lens? The periphery? Can stopping down a little help with that?

The distortion, as with most UWA lens, is on the periphery and is caused by the curvature of the lens elements so I don't think stopping down would help.

However stopping down to f5.6 gives the lens a big boost in edge sharpness.

I've never noticed the distortion in any astro shot and I've managed to correct it in architectural shots.

PS: I should add that if I was in the market today for an UWA lens I'd be having a VERY serious look at the new Tamron SP 15-30MM F/2.8 Di VC USD.

 

[Astrosurf]

Wow! Price! 

[Pankaj]

Great shot Kev. Especially, considering that this is a single sub. Have you ever tried taking more subs in RAW and then stacking with Darks and Bias frames. Out of curiosity, may I ask which software you use for post processing. I use dss for stacking and lightroom for pp.

Another thing - if I can understand correctly, then your camera was mounted on eq6. This is a tracking mount and hence star trailiong shouldnt come in 30 sec subs. Was it polar aligned?

But come what may be, this still happens to be a lovely single sub shot ! 

[DarkKnight]

11 hours ago, Pankaj said:

Great shot Kev. Especially, considering that this is a single sub. Have you ever tried taking more subs in RAW and then stacking with Darks and Bias frames. Out of curiosity, may I ask which software you use for post processing. I use dss for stacking and lightroom for pp.

Another thing - if I can understand correctly, then your camera was mounted on eq6. This is a tracking mount and hence star trailiong shouldnt come in 30 sec subs. Was it polar aligned?

But come what may be, this still happens to be a lovely single sub shot ! 

Hi Pankaj,

This shot was taken just before I got my EQ6 mount and the camera was tripod mounted. At 30secs with a 14mm lens I think I was right on the limit for star trailing.

This post was really an exercise in PP (with Photoshop CS6 in Adobe CC) and judging by the feedback it seems I'm on the right track. I only got the last pieces to set-up my mount a week ago and of course the weather has not been kind to me. I have tried a stacking exercise with DSS with Darks but no Bias frames.

If the weather man is right I'm hoping to get out in the next week to do some tracking with my now modded EQ6 (I've done the V4 SynScan upgrade).

Thanks you for your kind remarks.