Another M42 attempt

John O'Mahony · Post by **John O'Mahony** » Mon Mar 30, 2009 10:59 pm

Another and probably last attempt at M42 this year. This this time armed with a CLS filter and F6.3 focal reducer

M42. Stack of five 90 second frames using a Canon 450D and CLS filter at f6.3. Stacked in Deep sky stacker. CGE 11 a prime focus.

Here is one of the individual frames.
The frames seem to have a "skyglow" around them (maybe due to haze). I'm not sure how to remove this.

Frank Ryan · Post by **Frank Ryan** » Tue Mar 31, 2009 1:00 am

Very good John.
(I changed the links into images just to add a bit of
life to the post hope thats ok)

Looking at the single shot you should be able to tease out quite
a lot more from the final stacked image.
I don't use deep sky stacker because I found it cumbersome
but most DS imagers say its good.
I've often used Registax to stack shots but it can take an age
because of the size any you'd want a powerful machine to handle it.

Maybe try making copies and resizing the 5 images to someting smaller
then try a stack in Registax.
I usually just save the stacked image and then process it further in Photoshop.
Pete Lawrence wrote a great step by step article in S@N mag
a few months back about exactly what you are trying to do.
I'll dig it out and bring it in on Wed.

John O'Mahony · Post by **John O'Mahony** » Tue Mar 31, 2009 10:08 am

Cheers Frank

The stacked image has a wealth of detail -there is very good data in the actual stack. I just can't process it to get the best result. I'll bring my laptop on Wednesday

Conn Buckley · Post by **Conn Buckley** » Wed Apr 01, 2009 4:27 pm

Hi John, That is a terrific image of M42. It is almost 3 dimensional in places. The CLS filter seems to have made a great difference. Do you mind my asking where you sourced the filter? The 90 second exposures with minimum star trailing suggest the scope is equatorially mounted. Is it permanently mounted or is this something you have to do at every session? Again, well done and keep up the good work. Conn

John O'Mahony · Post by **John O'Mahony** » Wed Apr 01, 2009 5:03 pm

Hi Conn

Good to hear from you!
The scope is equatorially mounted but not permanently. A line of sight polar alignment is good enough for 1-2 minutes at prime focus at F6.3. Now if I could figure out how to dark flats with the cotton teeshirt I could get rid of that halo on he picture........
I bought the filter second hand off the IFAS boards but they are available from Telescope Service and BC&F.

Cheers