Star colours ! (My first Messier portrait :) )

[SilverAstro]

Prologue :
After (too!)many decades of visual I took the plunge into the the dark side with the purchase, a little while back, of a secondhand DSLR, Canon 60D, and a 'heritage' 135mm lens from my SLRfilm era.

But real life intervened and I still have not got a tracking or goto mount for it ! However, after seeing a video of a capture of the Andromeda galaxy made with loadsa short exposures stacked, I tried for the Beehive Cluster on a tripod.
Actually, truth be told, it was an excersize in how to remember where all the settings were inside the menu system ! Lots of failures mostly because of wobbles and bounce until I discovered live view and the 10sec delay timer.

So have a giggle ! (I wanted to compose it on the 1/3's but the pan&tilt was a bit too jiggly and it was cold out there)

Finally to the point of this post:
17 x 3sec exposures (10 then 5sec being too long)  still made wee trails. Will try 2 and 1sec next time out ! Stacked in DSS (and that was a learning experience!!)
BUT  what is going on with the star colours ? All the bright stars are white/crushed with colour only in the fuzzy outlines. It can't be over exposure at only 3sec can it ?

 

Epilogue:

I just discovered why my laptop was clogging up : the original was about 180Mb ! I have reduced it a bit (150Kb !) for display here,

now i need a new lappy !!!

 

 

[wxsatuser]

Brighter stars will easily burn to white leaving slight colour in a halo.

The colour of your stars does'nt look right, bright ones in M44 will be mainly blue with a few yellow ones.

It almost appears you have chromatic abberation, yellow stars have red on one side and the blue look to have magenta.

[alacant]

4 hours ago, SilverAstro said:

I tried for the Beehive Cluster

...and succeeded. Well done!

I'd rate colour as the most difficult step in processing. I found that working with a reference -a starting point say from an image you know to be balanced correctly- on screen with which to compare prevents you getting it wildly wrong. Having said that, an image search for m44 throws up all manner of colour schemes ranging from all blue, all white and all yellow with a rainbow of alternatives in between. As i say, difficult if not impossible!

Clear skies and good luck.

[wxsatuser]

21 minutes ago, alacant said:

...and succeeded. Well done!

I'd rate colour as the most difficult step in processing. I found that working with a reference -a starting point say from an image you know to be balanced correctly- on screen with which to compare prevents you getting it wildly wrong. Having said that, an image search for m44 throws up all manner of colour schemes ranging from all blue, all white and all yellow with a rainbow of alternatives in between. As i say, difficult if not impossible!

Clear skies and good luck.

In which case most of those images are wrong.
The spectral class of M44 stars is well known, the bright ones will be in the A F G K classes.
They will range from A=blue/white, F=white, G=yellow/white and K=yellow/orange.

These stars make up about 30% of the stars, most of the others are M dwarfs.

If using an unmodded dslr daylight white balance should give the correct colours.

[SilverAstro]

Thanks for your thoughts.

I am not at this stage worried about the actual / real/ absolute colours, of the stars, that can be investigated later and or adjusted in Gimp ! I was puzzled by white middles to all the bright ones although they are different colours relatively, as shown by their different 'hairy' fringes. It is a cruel pixel peek !

So it must be a saturation problem then, I shall see if/when I do another test at shorter exposures.  I had a nice clear sky last night, until I got the camera and tripod set up outside, , , then guess what !

[SilverAstro]

It might be that I have reduced the dynamic range by using too high an ISO !

If I am understanding this website correctly http://dslr-astrophotography.com/iso-dslr-astrophotography/   and http://dslr-astrophotography.com/iso-values-canon-cameras/

I had read previously that above a certain value ISO there was no extra performance available, but it is news to me that higher values causes a decrease in performance. Definitly time for some experiments !