Images from last Night - 28th Aug

[Mike]

Took these all last night - Not happy with them really. Stars still bloated on the raw files but the moon was up and transparency wasn't great. Still got a lot to learn. Need to get this guide camera working properly so I can do very long exposures.

IC5146 - Cocoon Nebulae - HaRGB 20:20:20:20


M1 - Crab Nebulae in Ha - 20 mins


NGC524 - Quick test image - Loads of galaxies in this area.



Part of NGC7000 - 30mins Ha

[Mike]

Found a technique to reduce star bloat - tried it on the Cocoon Nebulae image - What do you think ?

BEFORE


AFTER

[Whitters]

Some very nice images there mate, The Cocoon is one I have been meaning to image for ages.

The technique looks good, but it has an effect on the nebula. I have been trying some star bloat techniques, but they all seem to have an adverse effect on the nebula, as Chris pointed out, giving it a crinkley feeling. There must be a way to apply the anti-bloat and preserve the structure of the nebula.

[Mike]

I didn't mention it but I also messed around with an unsharp mask and the colour levels which is probably why the nebula looks different. I was trying to bring out more detail.

I think the image suffers from the poor seeing and transparency last night and only a short exposure. The moon was up and the entire sky was orange instead of jsut orange in the north so there was obviously water vapour in teh atmosphere.

I was mainly trying expermients to get the guide camera to work. It was obvious that the drift was less with the guide camera on but it wasn't eliminated entirely and i was trying to figure out why.

Once I have these problems ironed out then I can go for very long exposures of the faint objects. I am also trying to find out how to do the scripting in astroart so I can automate some of the processes as well as see if I can script something to centre objects to allow for the lack of a sync command in the SkyScan Controller software.

[Rocket Pooch]

There's a new Feature in AIP4WIN v2 to remove the bloat and not have the black ring around the star, just go to find it, Mike if you want me to give it a go on the Stacked image (without the filters etc being applied) I'll give it a go, also I found that any processing to the RGB should be applied before the Colour image not after or it all goes wobbly.

Lastly why do all my images on the Gallery have noise on them, the done on any of my 4 PC's before I put them up, strange?  

[Mike]

I think they were that bloated due to poor seeing more than anything. Seeing has a huge factor on the tightness of the stars.

I think Rick edit's the pics before posting them up to save space. The quicker we get our own webspace the better, which is something we will discuss with the committee at the meeting next week. Then we can put originals up at full size to be viewed.

[Rick]

The large images I put on the website are usually exactly as I've received them. Very occasionally I'll change the format or do something to reduce the size, but I've not done that to any of the images submitted recently. I do prepare thumbnails, and those will be re-scaled and cropped as seems good to me.

Chris, I can confirm I have not altered any of your recent images in any way, so anything that's happened to them must have happened either before I received them or in your web browser when you viewed them. Check to see whether your email program does anything to make image files smaller when it sends them.

[Mike]

Now that's interesting. I noticed that some of my images also looked like they had been compressed slightly. Also, the NGC7000 image I sent is flipped around the horizontal axis to the original. I wasn't bothered as it is an astronomical image. I presumed it was either you Rick editing them for compatibility with the website or an artifact from the Linux software you were using!

[Rocket Pooch]

Hi Rick,

Strange eh, must be something on the images I can't resolve at home on the PC's it only seems to show up on my rubbish monitor at work.  Odd eh.

Chris

[Rocket Pooch]

Have a look at this

Image from my web site

http://tinyurl.com/9wxsl

Image on the gallery

http://gal.orpington-astronomy.org.uk/gal165.html

There the same raw image jpg that is but they look different.

?
[/img]

[Rick]

The two images are not the same. The one I received in your email and put onto the gallery is 52105 bytes long:

52105 Aug 30 13:23 /www/gallery/large/CS_BubbleColour_20050816.jpg

The one I just downloaded from your website is 52846 bytes long:

52846 Aug 31 17:00 BubbleColour_20050816.jpg

Something has clearly done some additional work on it to reduce its size, and it has done it before it gets attached to the email. Check that there isn't a setting in the image-attachment part of your email program that's doing something to reduce the size of the image before it sends it.

If you point me at the other clean copies on your website then I'll put them into the gallery. That way we'll cut out the email program.

[Rocket Pooch]

odd eh!