Need just a little mentoring


Anthony Abby
 

Good morning everyone!  Haven't met most of you yet, but hopefully will soon.  I've always been interested in Astronomy.  It's fascinating and I'm enjoying learning.

I'm also very interested in Astrophotography.  I don't just want to view stellar objects, I want to capture them and continue to admire what I've seen.  And here's the ask..... is there anyone here than maybe wouldn't mind me asking questions about astrophotography?  Mostly about exposure at the moment?  Just when I think I understand what I should be doing, and why, I end up wasting an entire evening of exposures.  Like I did last night.  I'm missing something important, evidently.  And I'd really like to figure out what that is.


Jim Tallman
 

Welcome to the group Anthony,

  Just so you know, even when you get good at imaging, you will sometimes waste entire evenings due to one minor issue here or there.  To understand you situation though, what sort of mount are you using, EQ or Alt-AZ?  Are you using a Refractor, SCT, or Newtonian OTA?  What sort of camera are you using, CCD, CMOS, DSLR?

 

Each one of these configurations can pose different problems and require a different approach. 

 

 

Jim

 

From: BackBayAstro@groups.io <BackBayAstro@groups.io> On Behalf Of Anthony Abby
Sent: Wednesday, August 26, 2020 9:58 AM
To: BackBayAstro@groups.io
Subject: [BackBayAstro] Need just a little mentoring

 

Good morning everyone!  Haven't met most of you yet, but hopefully will soon.  I've always been interested in Astronomy.  It's fascinating and I'm enjoying learning.

I'm also very interested in Astrophotography.  I don't just want to view stellar objects, I want to capture them and continue to admire what I've seen.  And here's the ask..... is there anyone here than maybe wouldn't mind me asking questions about astrophotography?  Mostly about exposure at the moment?  Just when I think I understand what I should be doing, and why, I end up wasting an entire evening of exposures.  Like I did last night.  I'm missing something important, evidently.  And I'd really like to figure out what that is.


Anthony Abby
 
Edited

Thanks Jim!  At the moment I'm using a standard photography tripod, so no tracking.  I'm using the NPF rule (vice 500 rule) and manually adjusting alignment between sets.  Nikon D750 with either 24-120mm f/4 or Rokinon 135mm f/2 lens.  Having the same problem with either which is why I think I must be missing something.

I'm taking exposures between f/2 and f/5.  Have tried f/2, f/4, and f/5.  ISO 800 and shutter length at 2s when using the 135mm lens, and 4s when using the Nikkor 24-120 (@50mm) lens.  Only trying to image deep sky, wide field targets.

When I set up I focus, then take a test shot of the area I want to image.  Look at the histogram and adjust the fstop so the histogram is about 1/4 (or less) from the left.  Have not attempted to change iso yet, however.  Been told I should stick with 800 or 1600 for deep sky imaging.  With test image histograms looking good, and focus good, I start the camera imaging away.  100 images at a time when taking 2s, and 50 at a time when taking 4s.

But in all the instances where I was taking images from my pretty light polluted back yard, and last night at a much darker location, I often see a bloom of light in the final pre-processed image as soon as I start to do the first stretch in Photoshop.  When I was imaging in my back yard I thought it was my neightbor's back yard light, which was in the direction I was trying to image.  I couldn't find a location in my yard where I wasn't exposed to one of my neighbor's lights, or a street light.  So with the clear skies last night (finally!!!!) I went out into a more rural area and set up about 40-60' off a road and pointed south.  The moon was up, but about 20 degrees west of my camera orientation.  Didn't think it would be a problem.  There were also cars periodically driving along the road behind me, but the camera was pointed directly away from the road.  But I saw the same bloom of light when doing the first stretch in photoshop.


Nikon D750 w/Rokinon 135mm f/2 lens
800 iso
f/2
2s * 500 (16.6 minutes) 

So this has to be something I'm doing?  or not doing?  Not taking into account?  Any ideas?


Jim Tallman
 

Hmmm… well to tell you the truth, you might just be making things a bit harder than they need to be.  I use a Canon 3Ti or T5, and only use the Manual Setting with a bulb, or it is connected to my PC to let it manage the images. Se it to manual, with your exposure set to 30 seconds, find a bright star and center it up, then zoom in on it to focus, Then set up your exposure duration and take some shots.  800 ISO is fine, and I bet you could go to 1600 if you wanted to.

 

Her is one done at 800ISO and a 55mm Canon lens. Forgot the duration of the stack though

 

A star in the middle of the night sky

Description automatically generated

 

 

Try that first before you try to figure out the “bloom”, that is an entirely different issue.  Send me one of your raw images that you already have I’ll have a look.  Email jctallman2006@...

 

 

Jim

 

From: BackBayAstro@groups.io <BackBayAstro@groups.io> On Behalf Of Anthony Abby
Sent: Wednesday, August 26, 2020 12:56 PM
To: BackBayAstro@groups.io
Subject: Re: [BackBayAstro] Need just a little mentoring

 

[Edited Message Follows]

Thanks Jim!  At the moment I'm using a standard photography tripod, so no tracking.  I'm using the NPF rule (vice 500 rule) and manually adjusting alignment between sets.  Nikon D750 with either 24-120mm f/4 or Rokinon 135mm f/2 lens.  Having the same problem with either which is why I think I must be missing something.

I'm taking exposures between f/2 and f/5.  Have tried f/2, f/4, and f/5.  ISO 800 and shutter length at 2s when using the 135mm lens, and 4s when using the Nikkor 24-120 (@50mm) lens.  Only trying to image deep sky, wide field targets.

When I set up I focus, then take a test shot of the area I want to image.  Look at the histogram and adjust the fstop so the histogram is about 1/4 (or less) from the left.  Have not attempted to change iso yet, however.  Been told I should stick with 800 or 1600 for deep sky imaging.  With test image histograms looking good, and focus good, I start the camera imaging away.  100 images at a time when taking 2s, and 50 at a time when taking 4s.

But in all the instances where I was taking images from my pretty light polluted back yard, and last night at a much darker location, I often see a bloom of light in the final pre-processed image as soon as I start to do the first stretch in Photoshop.  When I was imaging in my back yard I thought it was my neightbor's back yard light, which was in the direction I was trying to image.  I couldn't find a location in my yard where I wasn't exposed to one of my neighbor's lights, or a street light.  So with the clear skies last night (finally!!!!) I went out into a more rural area and set up about 40-60' off a road and pointed south.  The moon was up, but about 20 degrees west of my camera orientation.  Didn't think it would be a problem.  There were also cars periodically driving along the road behind me, but the camera was pointed directly away from the road.  But I saw the same bloom of light when doing the first stretch in photoshop.

Nikon D750 w/Rokinon 135mm f/2 lens

800 iso

f/2

2s * 500 (16.6 minutes) 

So this has to be something I'm doing?  or not doing?  Not taking into account?  Any ideas?


Anthony Abby
 

Sorry if I wasn't clear.  I am set for manual mode, with shutter on bulb.  I'm using an external intervalometer.  Last night was set for 5s delay, then 2s exposure, with 2s wait between each exposure.  100 exposures, then I re-set camera alignment and start it back up again.  I use the same technique for focus, though I focused off Jupiter last night.  Was first time doing it and was amazed when I saw tiny dots pop up immediately around it when I hit the correct focus point.

So it sounds like I'm doing things right in terms of managing the camera and setting up for exposure?

I do take test exposures and then look at the histogram.  Based on what I saw I stepped down from f/5 to f/2 after two test exposures.  Histogram ended up at a little less than 25% from the left so thought that was fine.  And the moon was not in the view.   Based on my limited experience and knowledge I thought 800iso, f/2 with the 2s shutter length was the appropriate setting for last night.


Jim Tallman
 

Sounds like you are headed in the right direction then :)

 

 

Jim

 

From: BackBayAstro@groups.io <BackBayAstro@groups.io> On Behalf Of Anthony Abby
Sent: Wednesday, August 26, 2020 3:29 PM
To: BackBayAstro@groups.io
Subject: Re: [BackBayAstro] Need just a little mentoring

 

Sorry if I wasn't clear.  I am set for manual mode, with shutter on bulb.  I'm using an external intervalometer.  Last night was set for 5s delay, then 2s exposure, with 2s wait between each exposure.  100 exposures, then I re-set camera alignment and start it back up again.  I use the same technique for focus, though I focused off Jupiter last night.  Was first time doing it and was amazed when I saw tiny dots pop up immediately around it when I hit the correct focus point.

So it sounds like I'm doing things right in terms of managing the camera and setting up for exposure?

I do take test exposures and then look at the histogram.  Based on what I saw I stepped down from f/5 to f/2 after two test exposures.  Histogram ended up at a little less than 25% from the left so thought that was fine.  And the moon was not in the view.   Based on my limited experience and knowledge I thought 800iso, f/2 with the 2s shutter length was the appropriate setting for last night.


Anthony Abby
 

Through a LOT of experimentation Wednesday night and especially tonight I can now state with complete confidence that the flaring issue is the moon.  I've been trying to capture the Eagle Nebula area and the moon is just too bright.  After initial, additional experimentation earlier tonight I could see the flaring.  When I swap to the North American Nebula area no flaring.  Until I learn to deal with the moon, I'll just not shoot anywhere near its direction when its up.


Stu Beaber
 

Anthony...welcome to the world of astroimaging...You just solved possibly your first of about a gazillion things that can go wrong while trying to take a deep sky picture of the heavens...enjoy your journey.

Stu


On Sat, Aug 29, 2020 at 11:13 PM Anthony Abby <anthony.j.abby@...> wrote:
Through a LOT of experimentation Wednesday night and especially tonight I can now state with complete confidence that the flaring issue is the moon.  I've been trying to capture the Eagle Nebula area and the moon is just too bright.  After initial, additional experimentation earlier tonight I could see the flaring.  When I swap to the North American Nebula area no flaring.  Until I learn to deal with the moon, I'll just not shoot anywhere near its direction when its up.


vp
 

Anthony,

Wait a few days until the Moon gets out of the region of Sagittarius, and you won't have to deal with the flare.  

I never used to pay attention to the phases and rise/set times of the Moon until I got into amateur astronomy.  YOu can keep track of the Moon's "schedule" at the USNO Data Services website and get the rise and set times of the sun and moon for one day and you can see and download tables of sun, moon, and twilight schedules for an entire year.

One day:

Whole year:

Other:

George
On August 30, 2020 7:29 AM Stu Beaber <wd4sel@...> wrote:


Anthony...welcome to the world of astroimaging...You just solved possibly your first of about a gazillion things that can go wrong while trying to take a deep sky picture of the heavens...enjoy your journey.

Stu

On Sat, Aug 29, 2020 at 11:13 PM Anthony Abby < anthony.j.abby@...> wrote:
Through a LOT of experimentation Wednesday night and especially tonight I can now state with complete confidence that the flaring issue is the moon.  I've been trying to capture the Eagle Nebula area and the moon is just too bright.  After initial, additional experimentation earlier tonight I could see the flaring.  When I swap to the North American Nebula area no flaring.  Until I learn to deal with the moon, I'll just not shoot anywhere near its direction when its up.




George Reynolds 
VP, Back Bay Amateur Astronomers 
BBAA 
Outreach Coordinator
backbayastro.org