NGC7023. My first Iris Nebula.

[MARS1960]

Hi all,

I managed to get 15 x 360sec subs on the Iris nebula last night before the clouds spoiled it all.

Taken with my SW 100ED native fl, canon 60D with cls clip filter, guided and dithered with the Mgen.

Stacked in DSS and played with in my newly acquired PI.

Hope you like it.

Thanks for looking.

[wimvb]

Nice catch! Now the fun starts, trying to get as much of the dark nebulosity as possible out of the image.

Good luck,

 

[ollypenrice]

You've done very well with that. The resolution is excellent, the stars are small and round. There are delicate details within the blue part of the Iris itself. Looking at the colour noise in the outlying dust, I'd say that you will need more and longer exposures to pull that out and maybe layer such deeper data in using Photoshop. But for the data you have, I think you've made the most of it in a clean and natural job. The golden word in this mad game is - more!

Olly

[MARS1960]

17 hours ago, ollypenrice said:

You've done very well with that. The resolution is excellent, the stars are small and round. There are delicate details within the blue part of the Iris itself. Looking at the colour noise in the outlying dust, I'd say that you will need more and longer exposures to pull that out and maybe layer such deeper data in using Photoshop. But for the data you have, I think you've made the most of it in a clean and natural job. The golden word in this mad game is - more!

Olly

Thanks Olly, very encouraging words.

I guess it is time for me to start imaging an object over a few nights so i can gather more data.

[MARS1960]

On 10/26/2016 at 16:24, wimvb said:

Nice catch! Now the fun starts, trying to get as much of the dark nebulosity as possible out of the image.

Good luck,

 

Thanks, i'm going to need it.

[wimvb]

1 hour ago, MARS1960 said:

I guess it is time for me to start imaging an object over a few nights so i can gather more data.

Yes, that is a good way to go. @ollypenrice has commented on how best to do that, in the past:

align your camera with the RA and DEC axes of the scope/mount. This makes it easier to reframe a target if you can't leave the camera attached between sessions.

In order to align your camera, you take a long (30 secs?) exposure of a bright star. While the camera takes the image, you move the mount in RA. Afterwards you check how much of an angle you have between the star trail and the sensors edge. Rotate the camera and reshoot, until the trail is parallell to the sensors edge (either the long edge or the short edge).

Once you get into the habit of doing this, revisiting targets is a breeze, even if a year goes between revisits.

Good luck.

[ollypenrice]

You said you dithered. Did you use a large dither? For CCD the dither can be very slight but to combat colour mottle in DSLRs Tony Hallas recommends a large (~ 12 pixel) dither.

Olly

[MARS1960]

3 hours ago, wimvb said:

Yes, that is a good way to go. @ollypenrice has commented on how best to do that, in the past:

align your camera with the RA and DEC axes of the scope/mount. This makes it easier to reframe a target if you can't leave the camera attached between sessions.

In order to align your camera, you take a long (30 secs?) exposure of a bright star. While the camera takes the image, you move the mount in RA. Afterwards you check how much of an angle you have between the star trail and the sensors edge. Rotate the camera and reshoot, until the trail is parallell to the sensors edge (either the long edge or the short edge).

Once you get into the habit of doing this, revisiting targets is a breeze, even if a year goes between revisits.

Good luck.

That's great, thanks Wim.

[MARS1960]

2 hours ago, ollypenrice said:

You said you dithered. Did you use a large dither? For CCD the dither can be very slight but to combat colour mottle in DSLRs Tony Hallas recommends a large (~ 12 pixel) dither.

Olly

Yes Olly, 12 pixels, it is the default setting on the Mgen, when i bought it i knew very little about dithering so thought i would leave it on default.

[Knight of Clear Skies]

You've got some good detail coming through there on a challenging target. However, the background is very noisy. When stacking in DSS did you select the Kappa-Sigma clip option? This is great for removing noise when used with dithering. I'd also check a few subs to see if the target is offset between subs as you'd expect, to make sure the dithering is working. Looking at the histogram the background is also very bright, I'd try shifting everything to the left.

A couple other thoughts, are you taking darks? If the temperature profile doesn't match the lights this can introduce artifacts. And just to be sure, I take it the DSLR display is turned off when imaging? This can generate a lot of heat and extra noise.

Perhaps I'm simply underestimating how much the data has been stretched, was this shot at f9? If that's the case it may simply be a case of gathering more data - checking the Deep Sky Imaging section people do seem to throw a lot of time at this one.

[MARS1960]

7 hours ago, Knight of Clear Skies said:

You've got some good detail coming through there on a challenging target. However, the background is very noisy. When stacking in DSS did you select the Kappa-Sigma clip option? This is great for removing noise when used with dithering. I'd also check a few subs to see if the target is offset between subs as you'd expect, to make sure the dithering is working. Looking at the histogram the background is also very bright, I'd try shifting everything to the left.

A couple other thoughts, are you taking darks? If the temperature profile doesn't match the lights this can introduce artifacts. And just to be sure, I take it the DSLR display is turned off when imaging? This can generate a lot of heat and extra noise.

Perhaps I'm simply underestimating how much the data has been stretched, was this shot at f9? If that's the case it may simply be a case of gathering more data - checking the Deep Sky Imaging section people do seem to throw a lot of time at this one.

Hi,

Yes i use kappa-sigma option.

I really was unsure of what ISO to use even after a couple of test shots, I went with ISO1600, looking back maybe i should have went with ISO800, it was a tough call having never imaged it before, but next time i will shoot it at ISO800 and maybe 10min subs.

I'm not sure if it would benefit from using some 10min subs and some 5min subs as NGC7023  is a very bright cluster and has a very bright star and it looks like with even more data i could blow that core out, what do you think?

I dont take darks, i was advised i didn't really need to because modern DSLR's like my 60d have very good on sensor dark current suppression, after a bit of research i agreed.

Yes it was at f9, i agree more data really is whats called for here , next one will be better .