M42 last night

Hi guys,

Only actually the third session with my new scope last night, but it was crystal clear here in Larne with of course, only the Moon to spoil things a bit.

I got this shot of M42/43 and a tiny bit of NGC1977. It's a stack of 6 jpegs being 2 each of 10, 20 and 30 secs exposure all f5 with ISO 3200.



Clear skies,

Paul.

Hi Paul - a few (hopefully) constructive comments.

But before that, that's a nice image for your third go

1. Try improving the mount tracking accuracy if you can. There's a marginal trailing of stars top left to bottom right.
2. Try and take darks - this will eliminate the hot pixels (see those teeny weeny dotted trails?).
3. More data! Take as much data as you can - 100 10 second shots would really improve this image and drive the noise down (and it amounts to less than 20 minutes).
4. Hard to tell from this image but check that your 'scope collimation is good.

There's four things to try and and see what improvements you can make. Take your time over them and you'll be surprised at the difference you can make.

Now, as regards processing, I've seen lots of shots of M42 - all look different colour wise. Its a personal preference and your mileage may vary, but I prefer more muted tones. Still, its a very colourful region of the sky.

Still on processing, I'm not sure what software you are suing but see if there is the ability to bring out detail in the core without making the rest of the image disappear. In MaximDL its called 'digital development'

That'll all keep you going for a few weeks.

By the way, you image is waaaay better than anything I ever did on M42

What was your scope and camera again Paul? A suggestion perhaps - don't go for the ISO3200 again! Where there is a bright area, it will always be way over-exposed! You have captured a lot of stars in this field, but you have sacrificed clarity in the nebulosity at the Trapezium's center. But, I love the blues and purples!

Thanks guys!

My scope is a Meade LXD75 6" 750mm f5 Newt and my camera is a Minolta Dynax 5D - they seem to work well together!

1. I know the mount needs work - the polar scope and german north are in slightly different directions which is an alignment matter. Also the Autostar is set for Belfast whereas I'm 20 miles north so need to set up a custom location.

2. Yep, must do darks

3. Indeed, the difference between 1 and 6 frames is astonishing, but I've done webcam work with 600 frames and the image just keeps getting smoother with numbers. Mind you, at 6MP per frame, processing will be lengthy!

4. I'm no expert, but I think the collimation is pretty good - an object placed in the middle of the field is the one that becomes obscured by the centre obstruction when the eye is moved away from the eyepiece - is this the right test?

Thanks for the feedback guys - the fun of this is the learning!

Clear skies,

Paul.

Paul - with the fast Newts, collimation is usually important if not critical and should be checked more regularly than most other scopes. I've even heard of planetary imagers checking it every 30 minutes :shock:

Do a google on Newtonian Collimation and you should come across all kinds of resources - they will tell you how to do it. Its not terribly difficult.

Keep it up!

Cheers
Dave

4. I'm no expert, but I think the collimation is pretty good - an object placed in the middle of the field is the one that becomes obscured by the centre obstruction when the eye is moved away from the eyepiece - is this the right test?

Hi Paul,

The central obstruction will not cause a shadow or obscure the central object in the field of view as *every* part of the mirror contributes to *every* part of the image at the focal plane.

For critical collimation, don't bother with a laser collimator (only really useful for rough and dirty collimation on truss tube scopes) but get yourself a set of three Techtron Collimating Eyepieces. The first is a long barrelled cross-hair site tube, the second is a Cheshire eyepiece, and the third is a short auto-collimating eyepiece for super accurate collimation. They come with an excellent booklet "Perspectives in Collimation" by Tippy d'Auria. The Techtron set is *far* better than the combined collimating eyepiece sold by Celestron and others.

Phil.