DeepSky Camp August 2008

[Mike]

Looks quite nice. What about lighting though? Are there lights after dark?

It's 120 miles from Orpington so about 2.5 hour drive. Not too bad.

[RobertM]

Tony/John - sorry I wouldn't mix you up in real life, honest !

Fay, you do seem to have a thing about Miss Marple !

Daniel, that might be a possibility dependent on dates so let me know what you're thinking ...

God this is an active thread !

Cheers
Robert

[MarkS]

John,

As promised here is the central part of M16 at full scale. 
Modified EOS 350D on C11 at F5.6    10 x 5min at ISO 800.   No filter, therefore image includes infra-red.
Darks and flats were applied during processing. 
This is raw stack - I have not applied noise reduction or sharpening.

Mark

[JohnP]

Thks Mark for posting - level of detail is exceptional - shame about star bloat though - have you got any techniques for reducing star size?

Cheers,  John

[Carole]

Hi Daniel

there's a place called sixpenny handley just outside of salisbury, my nan and grandad used to live there and it's actually even darker than tuesnoad,

That was one of the areas I was looking into for an extra camp for next year, I hear it's very dark down there.  Would certainly be interested at some point, especially if others are going down there.

Mark your central bit of M16 at full scale is awesome. 

Carole

[Daniel]

I've noticed that about M16, those stars are so close together you cant help getting quite a bit of bloating on them, I guess underprocessing the starry area's then masking them in may help, that's how I got around the center of M42 burning out

Handley Is lovely, I used to visit there a lot, and as far as I could remember pitch black around the church (which is where the campsite is) that i used to go to at night to creep myself out

Gorgeous M16 though, loving all that extra colour depth you got

[MarkS]

John,

I can't immediately see how to reduce star bloat without resorting to nasty hacks in Photoshop.  For instance in the nebula areas, if the star size is reduced then the area "left behind" needs to be filled with nebulosity.  How can this be done without tampering?

Mark

[Daniel]

It might be possible to do it with another set of lower exposures, I've seen that done on M31 before to stop the middle buring out everything whilst still allowing a smooth transition from the center to the outside. but matching the nebulosity on the 2 resulting stacks would be tough.

[JohnP]

Mark - I think you are right. I took the image & ran it through one iteration of 'Astronomy Tools' reduce star bloat & it struggles (especially with full size crop) because some of the larger stars are actually joined - it doesn't do a good job of filling in the space when it reduces them. It worked a bit better on the larger image. I have emailed you a copy of the results so you can compare.

Cheers,  John

[Mike]

Has anyone tried to do a HDR merge using Photoshop? You take several exposures of different length to allow for the darka nd light areas then merge it into a High Dynamic Range image in photoshop to produce the desired result? I've been reading up on this for traditional photography using DSLR's, but just thought it should also apply to astro images.

[Rocket Pooch]

This is with a minimum filter applied to reduce the star size, you also need to deconvolute for the star shape and align the blue then it will be ok, can you e-mail me a BMP of the big picture and i'll post process it.

[Fay]

Mike, I was interested in trying that HDR Merge, but it is not in my version of Photoshop CS. It is on the next one up.

[Mike]

The stars have gone rectangular in that image Chris.

[JohnP]

OK - well here is my rework of the wider FOV image... I think stars are a little smaller... I also removed blue halo's...

Mark - Hope you don't me me posting....




John.

[MarkS]

John, Chris, 

You're producing some interesting results - reducing the star bloat
No, of course I don't mind you posting those experiments.

Chris - I'll send you a BMP (or TIF) tonight.

Mark