Advice on image plan for first ccd image run

[Singlin]

This evening I am hoping to get my first image run with a ccd.

I have chosen the Pelican Nebula and I have about 5hrs imaging time from when the Pelican is on my zenith to when it is just above my western horizon.

I have LRGB filters and an Atik 383L and a F4 10" Quattro Reflector.

The 5 hrs is calculated imaging time, I have another hour spare to enable me to put the pauses between shots etc.

  I am looking for advice on how to allocate this time between my variuos filters.

Regards,

Simon

[nmoushon]

With LRGB imaging the most detail will be coming from your L. So dedicate to most time to this. For only one night of imaging I would dedicate 3.5hrs to the L at binning 1x1. Then that would give me 30min for each of the RGB filters, though I would do binning 2x2. That is assuming you are doing 5 or 10min subs? If you are are planning multiple nights on this target then, me personally, would do 1 sub for RGB and then the rest as L. This would give me the most detail to play and the RGB to give just a bit of color. I personally like to do as much of one filter in one night as possible and almost always start with getting my L data full. This way on the night that I do all my RGB, or multiple nights if need be, I can play with the L data in PS and see what the data is like. It also give me a sence as to how much RGB I should do or if I need to go back and do even more L.

[wuthton]

With LRGB imaging the most detail will be coming from your L. So dedicate to most time to this. For only one night of imaging I would dedicate 3.5hrs to the L at binning 1x1. Then that would give me 30min for each of the RGB filters, though I would do binning 2x2. That is assuming you are doing 5 or 10min subs? If you are are planning multiple nights on this target then, me personally, would do 1 sub for RGB and then the rest as L. This would give me the most detail to play and the RGB to give just a bit of color. I personally like to do as much of one filter in one night as possible and almost always start with getting my L data full. This way on the night that I do all my RGB, or multiple nights if need be, I can play with the L data in PS and see what the data is like. It also give me a sence as to how much RGB I should do or if I need to go back and do even more L.

Couldn't agree more.

Just to add, unless you're dithering you don't need to pause between subs as no chip cool down time is required.

[nmoushon]

Just to add, unless you're dithering you don't need to pause between subs as no chip cool down time is required.

This is true too. Though I personally do a 5 sec pause just to make sure the data is all transfered correctly. Though even that is technically not needed. I just usually tend to be a bit over cautious, but thats just me.

[ollypenrice]

Sorry, but I couldn't agree less, I'm afraid! This is a region stuffed with stars which will soon dominate the image entirely. Your best weapon against this problem, especially in a fast Newt, is not to shoot any L at all. As well as increasing the star size it will burn out the star colour.

The Pelican is a strong Ha object and will soon give you fine signal. I would go for long Ha subs, not less than 15 minutes and perhaps 20. For the rest I'd shoot RGB. I'd start with the blue while the target is at its best and then go green, red, Ha. The Ha will hold up best at low elevations in which the first to suffer is blue.

In processing I'd add the Ha to red in Blend Mode Lighten, though I would also add a hint as luminosity. Maybe 15%. It should bring down star sizes and lift the faint detail.

If there is a threat of cloud then you might prefer to run the wheel HaRGB in succession to ensure you have something to process in the morning.

Here's an HaRGB NAM-Pelican. No luminance.

Gotta keep those darned stars down!!   The Ha will do it for you because NB stars are tiny, so you can haul out the nebulosity without generating large stars. It will also generate more small scale contrasts than Luminance on a target ike this. Luminance is great for galaxies, for dark objects, for dust, for reflection nebulae, but it is a blunt instrument on emission targets and a devil with the stars.

Olly

[nmoushon]

Sorry, but couldn't agree less. This is a region stuffed with stars which will soon dominate the image entirely. Your best weapon against this problem, especially in a fast Newt, is not to shoot any L at all. As well as increasing the star size it will burn out the star colour.

The Pelican is a strong Ha object and will soon give you fine signal. I would go for long Ha subs, not less than 15 minutes and perhaps 20. For the rest I'd shoot RGB. I'd start with the blue while the target is at its best and then go green, red, Ha. The Ha will hold up best at low elevations in which the first to suffer is blue.

In processing I'd add the Ha to red in Blend Mode Lighten, though I would also add a hint as luminosity. Maybe 15%. It should bring down star sizes and lift the faint detail.

If there is a threat of cloud then you might prefer to run the wheel HaRGB in succession to ensure you have something to process in the morning.

Here's an HaRGB NAM-Pelican. No luminance.

Gotta keep those darned stars down!! 

Olly

I would agree with you assuming he has an Ha filter. He only mentioned LRGB, not HaRGB. Though if he has an Ha then most definately use that over L. But if he doesnt then would you still suggest not using L at all?

When you mentioned L burning out the stars wouldnt a seperate star layer fix that though?

[ollypenrice]

Doh, sorry, I must have dreamed Simon's Ha filter! I've been working on HaRGB all afternoon so I may have it on the brain...

Yes, I'd shoot some L in that case. Probably parity in all filters. You need to get to know the kit, really. Don't forget that you can pull a synthetic L out of the RGB and combine it with the true L. I'd weight it at about 25% of the true L.

Simon, you need an Ha filter!

Olly

[Singlin]

Sorry I forgot to mention that I do indeed have an Ha filter.

[Singlin]

How long would you reccomend the rgb subs to be in seconds?

[nmoushon]

Sorry I forgot to mention that I do indeed have an Ha filter.

Holding out on us eh?! lol Well if you do, then indeed go by what Olly suggested. Its a very heavy Ha region and it will do a LOT better than the L would.

[Singlin]

Would this do?

6x 600 sec  B

6x 600 sec  G

6x 600 sec  R

6x1200 sec Ha

[ollypenrice]

Would this do?

6x 600 sec  B

6x 600 sec  G

6x 600 sec  R

6x1200 sec Ha

Probably. I can't guess how the top end of the brightnesses will play in your scope but F3.9 with larger pixels was never a problem in the Baby Q. Give it a whizz!

Olly

[Singlin]

Thanks for the help.

I am in the observatory focusing at the moment and at 21:45 the moon will have dissapeared behind the ridge and the pellican will be at my zenith ready for the run.

[Nathan_Pembs]

Some interesting advice there Olly re: not using luminance on some targets, good to know

[Singlin]

Everything seems to be going smoothly exept I don't know for how long as I can see a mist front slowly moving up from the valley below.

So far I have done one Ha sub of 20 minutes (to check my guiding) 6x 600 sec Blue and I am in the process of doing the greens.

Attached is my 20min Ha sub

[Singlin]

Here is the link to the Fits file of the 12000 sec ha sub

https://www.dropbox.com/s/gbzy19swscai89u/Pelican%20tttt_000.fit?dl=0

[nmoushon]

Thats a great looking sub. Best of luck out there tonight.

[Singlin]

I have just woken up and checked my images.

I managed to capture everything except for 3 Ha's

I will do them tonight.

Everything is dripping wet but all of my glass seems fine.

[Singlin]

I learned another lesson today.

When shooting a subject that requires capturing low on the Western horizon chos a guide star that is above it in altitude.

I lost at least one sub because of this.

[ollypenrice]

That's a fighting sub! Tiny stars, smooth, and perfectly guided. You can't go wrong. I'd call it perfect. In processing you can tease up the contrasts. You've had a battle but you've won it!

Olly

[Singlin]

Thanks Olly!

                    

[Astrosurf]

This is a stonking thread! I've just bought an ATIK 314L+ mono plus filter wheel and will buy filters tonight. I hope to get an Ha filter soon. My only concern is that my guiding can be dodgy and 20mins would scare me silly!

Thanks for all the info and for Singlin for starting the thread!

Alexxx

[tingting44]

where do people get there Ha filters from for your CCD's? i see FLO do not sell them....

[DaveS]

Here

http://www.firstlightoptics.com/narrowband/baader-narrowband-ccd-emission-line-h-alpha-filters-125.html