M101 LRGB

[Carole]

I took the luminance for this back in August at Blacklands and been waiting ever since to get RGB which i got at Mark's last weekend.

It came out very yellow and I had a devil of a job to get the colour looking anything like what I felt was the accepted colour.  Using the WOZS71 and focal reducer to match what I was using initially I had to do a fairly big crop.  This is one difficult little sucker to image.  I don't think I am going to get any better detail than this with current kit.  

Lum 14 x 600secs NEQ6
RGB 6 x 300secs each HEQ5
WOZS71 Apo and FR, Atik383L
DSS, Registar and PS CS3

[MarkH]

It's an interesting point you make about colour Carole, it's a question I've raised before. Who or what is the governing factor about what the colour of any celestial image should be?

[Mike]

Mark,

Most images are colour corrected purely for the satisfaction of the person making the image.

It is possible to make a scientifically accurate colour balanced image by calibrating your processing on a star of a known type and colour.

But, as we produce images for fun and not for scientific benefit we are more interested in the aesthetics of the image rather than its accuracy.

[JohnP]

looks too purple to me Carole...

[MarkH]

Mark,

Most images are colour corrected purely for the satisfaction of the person making the image.

It is possible to make a scientifically accurate colour balanced image by calibrating your processing on a star of a known type and colour.

But, as we produce images for fun and not for scientific benefit we are more interested in the aesthetics of the image rather than its accuracy.


Thanks Mike, I see your point.

[Carole]

looks too purple to me

It's supposed to be blue, amazing how a 2nd pair of eyes will see something that eyes that have been looking at it for ages can't see.

Carole

[RobertM]

Did you use a CLS filter ?

[Mike]

There is a slight violet bias on my monitors but nothing i'd say was OTT.

[Carole]

Did you use a CLS filter ?

No CLS filter Robert.  Both dark sites.

It's more to do with my processing as I was struggling to make it more blue than the yellow it originally came out, which I didn't think was right looking at other images on the web.    

Carole

[Mac]

It's an interesting point you make about colour Carole, it's a question I've raised before. Who or what is the governing factor about what the colour of any celestial image should be?

I agree with mike inthe fact that most of us produce colours that are pleasing, although some do use the hubble pallet.
If you take RGB images of a test subject at the end of your garden, i.e. a calibration chart and then process this image, you will be able to get accurate timing data
for the correct exposures for your filter and camera set up. Then all you need to do is process the images in the same way.

If you are going to be scientific, you would probably need to take in to account red shift of the image, depending of the distance to the object.
but dont forget Ha for Red, Hb for blue Siii for green,.

http://forum.orpington-astronomy.org.uk/index.php?topic=9038.msg63695#msg63695

Mac.

[Carole]

I am not interested in being scientifically accurate, just a pleasing result, but one that looks like what the majority seem to produce.  As you say you can do as you like with narrowband, but this isn't a NB image.

For interest this is the original colour that the image came out.  Also this is a less cropped version which shows a few more galaxies.
The data wasn't so good on the blue as the sky conditions were deteriorating.  It's still showing that reflection (or whatever it is) on the left which i haven't bothered to process out in the yellow version:

I'd like to have another crack at this object with my Atik314 and SW ED120.  

[Mac]

As you say you can do as you like with narrowband, but this isn't a NB image

But a red filter is just that, its for the red part of the spectrum, irrespective of weather its a narrow band or not,
Red is Red be it narrow or wide, when you start using the RED for other colours i.e the hubble pallet, then you open up a mine field.

Mac.

[Carole]

I'm talking about Ha, Oiii and Sii which is commonly referred to as narrowband. 

Carole