M17 Ha data

Paul Haese · #1 23-05-2010, 09:28 PM

This is such a cool looking object at this image scale. I could just get it on the sensor on the narrow field of view. I just love the knots located over and throughout the nebula.

The subs were 15 minutes long and I think I could have done with 20 minute subs. Noise is really good as I can now image at -20C.

I will have to wait until next month for the colour data and luminence layer.

Click here for image.

Comments welcome.

Vanda (Ian) · #2 23-05-2010, 10:10 PM

Looks good to me Paul. The nebula shows some fine structure.

strongmanmike (Michael) · #3 23-05-2010, 10:19 PM

Nice contrasty version Paulie...maybe could be lightened up just a little..?

Looks cool though

Mike

Paul Haese · #4 23-05-2010, 10:24 PM

Thanks guys for the commments.

Mike, yeah I reckon you are right. The image could be brightened just a bit more. I will take a look at it soon.

Paul Haese · #5 23-05-2010, 10:35 PM

Quote:

Originally Posted by strongmanmike

Nice contrasty version Paulie...maybe could be lightened up just a little..?

Sorted, take another look now mate. What do you think now?

strongmanmike (Michael) · #6 23-05-2010, 10:57 PM

Yeh better IMO

Mike

TrevorW · #7 23-05-2010, 11:07 PM

Good one Paul should look great when all the pieces are put togethor

Moon (James) · #8 24-05-2010, 09:59 AM

Nice one Paul. I think you framed it just right.
What are the two diagonal lines in the lower right? I notice they also appear on this picture too. Is there a bright star nearby?

James

Paul Haese · #9 24-05-2010, 10:16 AM

James those are as you guess a reflection of a bright star just outside the field of view.

wysiwyg (Mark) · #10 24-05-2010, 01:54 PM

Paul,

I'd say your image is either slightly out of focus or your guiding was not quite up to scratch. The knots should appear a lot sharper.
Also the stars on the right hand side of the image seem elongated so you may have some tilt in your imaging train.
Try adjusting your midtone contrast and maybe running the image through a high-pass filter in PS, only very slightly though.

Mark

RB (Andrew) · #11 24-05-2010, 02:19 PM

Quote:

Originally Posted by wysiwyg

Paul,

I'd say your image is either slightly out of focus or your guiding was not quite up to scratch. The knots should appear a lot sharper.
....
Mark

It's a lovely image indeed, but I noticed the same thing that Mark just said when I first saw the shot.
It's just a tad soft IMO and the knots should appear sharper.

Paul Haese · #12 24-05-2010, 02:37 PM

Quote:

Originally Posted by wysiwyg

Paul,

I'd say your image is either slightly out of focus or your guiding was not quite up to scratch. The knots should appear a lot sharper.
Also the stars on the right hand side of the image seem elongated so you may have some tilt in your imaging train.

Mark

No not slightly out of focus; just not sharpened. This is how narrow field images look before sharpening. I have done a hi pass now and you should see this as being sharper. I was going to sharpen the image before I posted it but thought given this is not a final image, it would not be a problem. I should have known someone would have picked this up.

The elongation of the stars is a mystery to me. On an image of Eta taken earlier in the evening the guiding was perfect and no evident tilt. I suspect that the guide settings for this target will need some slight tweeking or I have some slight slop in my focusor (Feather touch) which is a possibility too. Yet another nuance of narrow field is how tight everything must be to make it look right. You wide field guys will one day come across this when you see the light as it were.

Every thing is easy at wide field, it gets significantly harder when imaging at great focal lengths.

I think to make the image brighter it just needs 20 minute subs rather than the 15 minute subs I have here. This image has already has a signficant midtones adjustment, so really it just needs more photons.

Thanks for taking the time to make comment.

Hagar (Doug) · #13 24-05-2010, 04:36 PM

Looks good Paul, Ha works well when blended well but can a bit of a bugger to get right. This looks good though with great detail but might be a bit contrasty as it is.

gregbradley · #14 24-05-2010, 10:36 PM

I am viewing it after you've done some tweaks and to me it is very impressive.

Some stars can look elongated when in fact they are merely double stars (binaries) and just beyond the resolution of the scope to differentiate. Some stars of course can be elongated by tilt.

Yuri from TEC did an interesting test on the Feathertouch 3.5 inch focuser he uses in his APOs. The result of deflection tests showed there was slightly less deflection under a certain load when the focuser was upside down. So perhaps try spinning your focuser upside down and see if the tilt persists.

Greg.

Paul Haese · #15 25-05-2010, 09:56 AM

Greg that is a great idea I will take a look at it on the next object I image. For now this will have to wait. I am not sure but I think I might already have it over on its side at present.

multiweb (Marc) · #16 25-05-2010, 04:52 PM

Details are great Paul but there's something missing. In the dynamic range maybe. I'm not sure what. It looks a bit flat to me but then again might be because I always burn the hell out of my M17s. Very good start for a NB pic though. Looking forward to more.