M81 & M82 LRGB

[Carole]

Taken at Cairds campsite
Lum 6 x 600secs
Red 4 x 1200 secs + 2 x 900secs binned x 2
Green 4 x 1200secs + 2 x 900secs binned x 2
Blue 4 x 1200secs + 3 x 900secs binned x 2
Plus some Ha data for M82 taken from from last summer's image at Kelling
Total 6 3/4 hours but the binned data is worth a further 1 3/4 hours)
Needs bags more data
There were horrible gradients to try to process out.

WO ZS71 + FR
Atik460 and Baader filters
HEQ5

[JohnP]

doesn't quite look in focus to me or there has been some drift due to long exposures... just would have expected more detail seeing shot at dark sites with over 6hr of data... did you refocus your RGB data between filters - there are a lot of blue halo's.... good effort anyway - have you tried adding some Ha...

John

[Carole]

Didn't do any Ha John, but added a bit to M82 from last year's data.

This WO scope is notorious for blue halos unfortunately.  I checked all the filters before I started with my Bahtinov mask and they were all the same focus except for Oiii which I wasn't using anyway. 

Bit disappointed with the results to be honest, as like you I was expecting more detail in a dark site, but there was only 1 hour of luminance, all the rest was RGB.

Carole

[RobertM]

Perhaps a bit out of focus but there's definitely a problem with registration, colour fringes all over the image.  You could try a sharpened luminance mask to try to reduce star sizes.

Robert

[Carole]

I use Registar for registering the images, so don't know what else I could do. 

You could try a sharpened luminance mask to try to reduce star sizes.

I can do a sharpened Luminance mask but how do I use that to reduce the star sizes?

Carole

[RobertM]

Registax must have had a bad day why don't you try photoshopping it (adjusting the rgb planes to overlay more exactly).

If you apply a mask over the top then it will only let through what the mask allows.  That's what masks are for.  If you haven't used a mask yet then it might be worth investigating the technique, it's very powerful.

[MarkS]

Carole,

The image is definitely out of focus but something else is not making sense to me.  I really can't believe that is more than 6 hours of data.  Here is a crop of a single uncalibrated 90sec sub I took the same night.  Bear in mind that my stars are severely attenuated by the Sony "star eater" algorithm and some of them have the peaks bitten off - replaced by a hole.



The Tak+Sony A7S is a good combination but I don't think it can account for that much difference.

I really think something has gone wrong somewhere in your processing and/or acquisition. 


Mark

[Carole]

I'll take another look at it when I get time.  Lots of things going on at the moment.

Carole