M20 Trifid Nebula

[bloodhound31]

This picture is comprised of 15 minute subs, totaling 4.5hours of exposure.

Located in the constellation Sagittarius, the Trifid nebula is a beautiful combination of reflection nebula (blue) and emission nebula (red).

Telescope Skywatcher Black Diamond ED120
Camera Orion Starshoot Pro

Thanks for looking.

Baz.

[desler]

Always happy to look when they're that nice.

Well don Baz.

Darren

[peter_4059]

Wow Baz - 4.5 hrs - that's dedication and long subs. The guiding looks good.

Well done.

Peter

[troypiggo]

That's excellent! Well done! Keep that one on file for the POTN challenge coming up. ;)

[jjjnettie]

Love it!

[Bolts_Tweed]

Well done Barry- the triffid is just a joy

I just noticed that you are using the same gear as I am at the moment and you have far less coma than I am getting - I have a big question over optical alignment on mine with the Orion camera - my 2 inch extension tube has only one screw (GSO extension tube) while the camera nose piece is set up for a compression ring - i suspect the holding screw is sitting just near the edge of the compression ring recess - slightly kicking the camera out of optical alignment.

Are you using a one screw extension tube or a compression ring type tube?

The other alternative is I replaced the focuser with a moonlite motor focus and that may be the problem - at least I can collimate that but I think I will have to invest in CCD Inspector.

Anyway bottom line is that it is a very nice image mate - well done

MB

[bluescope]

Looking good Baz ... do you have a field flattener in your imaging setup ? Might be worth it to get rid of the coma in the corners of your images ... only if it bothers you ofcourse mate !

I wouldn't suggest a reducer/flattener as your fov is already quite wide ... just a flattener like an MPCC or the like. I bought the WO Flat 68 4" field flattener with my FLT110 but I actually prefer to use my MPCC with my SBIG camera.

:thumbsup:

[bloodhound31]

Thanks heaps mate. I have exactly the same problem. It is this kicking off that causes more coma in my top right corner than normal. I am going to drill and tap two more holes at 120 degrees around the holder and put in two more thumb screws. This should straighten it up. After that, a flattener is the next step.


Thanks Darren:thumbsup:


Thanks Peter, I'm loving this autoguider and ED80 on top of the EQ6. All guiding problems of the past have disappeared!


Rightyo Troy, will do. Cheers mate.

That's even better than like! Cheers Jeanette:thumbsup:


Thanks for the advice there Steve, I will look into it. Sounds like I could use one. As you see from my answer above, I think the kick off from the single screw is causing the coma in the top right (The image is cropped very slightly to get rid of the worst of it.)
That's the good thing about these wider fields, the DSO is usually small enough in the frame that you can afford to crop the edges off without losing effect.

Cheers,

Baz.

[Bolts_Tweed]

Thanks Barry - that is reassuring- I will try the same thing before I go spend any more money on a compression ring extension tube.

MB

[Alchemy]

lookin pretty good, nice colors

[gregbradley]

Very nice image Baz.

Are you imaging from a dark site or from suburban Canberra?

As you point out there is some tilt as the top right shows more coma than the other corners. None of it is eye catching though. A coma corrector would help. I found 3 tightening screws were really needed
for accurate squareness or preferrably (what I normally use with one or two exceptions) screw on adapters to minimise flexure and obtains almost perfect squareness. You also get the exact spacings for your flattener (they have a tolerance that is stated in +/- mm for accurate performance).

Greg.

[bloodhound31]

Thanks Greg,

I am in the suburbs mate, to the south of the city.

Once I have got the next lot of images out on the Helix, I am going to take all the camera gear off, pull the adapter out and go drill and tap two more grubs in it. I have a lathe at my disposal so I might make a screw on one later.

I would like to know more about flattener spacing though, what's the story with that?

Baz.

[Tamtarn]

Nice image good colour. Those long exposures are paying off Baz:thumbsup:

[Ric]

Well done Baz, a lovely capture with good detail and colour.

Cheers

[bloodhound31]

Thanks Barb, David and Ric.

I'm getting all antsy now for the new moon in two days!!!! YEEHAAARR!

Although if it is clear 3 or 4 days either side, I will be out there regardless...good enough!!

Eye of God, HERE I COME!!! Woohooooooooo!!!!

Baz.

[gregbradley]

I would like to know more about flattener spacing though, what's the story with that?

Baz.[/QUOTE]


Flatteners and reducers have a metal back distance. Metal back distance is defined as the distance from the rearmost metal part of the reducer or flattener to the plane of the CCD chip. This is where it has been optimised to work best.

So you whatever reducer or flattener you get you need to find out what the metal back distance is for it. Then you will need an adapter made to be that length so your camera is at the correct distance from the flattener.

You will also need to know how far the surface of the front of the chip is set inside the camera body. This is usually stated in the specification for the camera and often there is a little white mark often with a small circle on it, that tells you where the front surface of the chip is. Now you can measure that distance.

Greg.

[bloodhound31]

Ahh, I see...thanks Greg. So I understand it is the distance from the chip, not the distance from the objective, which will change with focusing rack in or out.

Does a flattener interfere any with the transmission of light?

[Paul Haese]

Nice Barry, your skills are coming along nicely.

[bloodhound31]

Thanks Paul, I am a bit of a slow learner, but I never give up!

[Hagar]

Very nice rendition Baz. 4.5 hrs seems an awfully long exposure on this target.

[bloodhound31]

Thanks Doug.

I have noticed that when I am limited to shorter exposures, I have to stretch them too much to bring out the desired effect. Then I have to use post-processing tricks to smooth the artifacts out. Noise reduction etc.

Now that I am taking very long subs, (15 minutes) and many more of them, with lots of flats and lots more darks, the result is a LOT LESS playing around with the image, giving it a much more natural feel.

I reckon the less you have to do to an image after you have taken it, the better.:thumbsup:

Baz.

[Robbie]

Nice Image, great FOV, my favorite target :thumbsup:

[CoolhandJo]

Very pretty - well centred - wide field

great.