Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

I'm about to give AP up !

astrophotography
  • Please log in to reply
34 replies to this topic

#1 BigE

BigE

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 26 Mar 2020

Posted 07 August 2020 - 03:49 PM

Hello all ... 

Celestron 6SE

Single-Fork Motorized GoTo Alt-Az Mount

Celestron f/6.3 Reducer/Corrector

Celestron StarSense AutoAlign Telescope Alignment System

Dew shield on

 

Nikon D5000

Intervalometer

 

 

So I was out last night , clear night, seeing and transparency and humidity were good.

Bortle class 8-9

Attempt at M101. (NW at 22:30 CST) +45°

I took 111 subs of 75 seconds each.

about 40 darks, bias, flats each.

 

I used DSS to stack them.

RAW Files processing---

 Bilinear interpolation

 Set black point to zero

STACKING Parms---

 standard mode

 Kappa-sigma clipping

 Alignment automatic

 

But my 16bit .Tif file only showed a few stars and no hint of M101....

 

I will share my .tif file if anyone is interested ... I don't know if its the subs or the Stacking OR maybe I need to 

Process them before I can see anything...

 

I have Photoshop CC for post processing.

 

ANY help or thoughts will be appreciated.

 

Sincerely

(about to give up)

Ernie

 

 

Here is the Link to Google Drive and the file...

 

https://drive.google...ew?usp=sharing 


Edited by BigE, 07 August 2020 - 04:04 PM.


#2 klaussius

klaussius

    Viking 1

  • *****
  • Posts: 707
  • Joined: 02 Apr 2019
  • Loc: Buenos Aires

Posted 07 August 2020 - 03:56 PM

You have to stretch the tiff produced by DSS, and M101 will pop up. Under that much light pollution M101 is drowned out by sky glow, but after about 2h of integration you should see something after you stretch.

 

You will also have to remove the sky glow (light pollution) to reveal M101.

 

If you want some help with procesing, post a link to the tiff and people will provide some pointers. Which software are you using for post-processing?


  • Dynan likes this

#3 mbechtel

mbechtel

    Explorer 1

  • *****
  • Posts: 82
  • Joined: 22 Oct 2014
  • Loc: Bloomington Indiana

Posted 07 August 2020 - 03:57 PM

First, make sure M101 was actually in the field. Submit your tif to astrometry.net just to make sure.



#4 SilverLitz

SilverLitz

    Apollo

  • -----
  • Posts: 1,054
  • Joined: 17 Feb 2018
  • Loc: Louisville, KY

Posted 07 August 2020 - 03:57 PM

Wrong mount and scope for DSO with that long of exposure.  Need GEM and autoguiding, and possibly less FL.  Light pollution will require a lot of integration time.

 

In Ps, look at histogram and raise black point to just left of the histogram's toe, and reduce the white point to just right of the long histogram's right tail, and then try stretching by moving mid-point slider to the left.  


  • ks__observer and OhmEye like this

#5 Gipht

Gipht

    Vanguard

  • *****
  • Posts: 2,499
  • Joined: 12 Nov 2016
  • Loc: Prescott Valley, AZ.

Posted 07 August 2020 - 03:59 PM

Ernie, M101 is a  tough target, and especially so with a longer focal length scope.  The longer the focal length, the longer the exposures have to be to get decent detail.  My guess with your telescope and reducer  would be that 4 minute exposures are needed, and that is not likely to be possible with and alt/az mount.

 

If you searched for pictures in Astrobin for results with your telescope, you would see a lot solar system photographs, and some very bright objects.


  • John O'Grady, rekokich, dron2015 and 1 other like this

#6 OhmEye

OhmEye

    Viking 1

  • *****
  • Posts: 788
  • Joined: 15 Sep 2019
  • Loc: Western NY Southern Tier

Posted 07 August 2020 - 04:11 PM

That focal length requires a good EQ mount for exposures of any useful length. If you did have M101 in frame it will need processing to see anything, and I expect it will have rather significant field rotation. I'm a bit surprised that DSS would be able to register the subs.



#7 SkyHunter1

SkyHunter1

    Mariner 2

  • *****
  • Posts: 242
  • Joined: 09 Nov 2017
  • Loc: Long Island NY

Posted 07 August 2020 - 04:11 PM

I agree with all of the posters actually, but I also agree with klaussius that you should post your subs and/or a unstretched stack and see if we can process it. 

 

Your scope at f10 is not optimal, but I would think you should have something there for that integration time.

 

Also, as one poster mentioned, make sure you have it in the field.

 

Regards,

Skyhunter1



#8 idclimber

idclimber

    Messenger

  • -----
  • Posts: 469
  • Joined: 08 Apr 2016
  • Loc: McCall Idaho

Posted 07 August 2020 - 04:11 PM

Again, upload a single tiff file or better yet the raw .nef file somewhere where the group can open it and see what you got. 

 

Your scope and mount are not optimal for this (beginning Astrophotography). This was stated above and is worth repeating.

 

If you are open to the suggestion to replacing the mount, with help here you can get this working. You have a good scope that with a focal reducer puts in reach of a beginner. It is certainly much easier than it was on my 12" SCT with a similar mount. 

 

If you are not interested in upgrading the mount then you can get good images of M101 and with very little additional investment. Put the Nikon away and purchase a small EAA suitable camera instead. Something like the ASI224MC is perfect for imaging live at the scope. Your existing mount is adequate for that task. You essentially run software that live stacks the images. It would also work well for planetary with the substitution of your focal reducer with a Barlow. 



#9 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:11 PM

In starting out, particularly from a Bortle 8 & 9 I would recommend selecting a brighter deep sky object to begin with.

One that will be eazier to image given your sky conditions.

Considering trying a globular cluster like M13 as an initial target and work at get good imaging results on an object like that.

I'm assuming you are just starting out?

 

Bortle 8 & 9 skies present a significant amount of light pollution. 

I image from a Bortle 6-7 red zone and I rarely (not often) bother to image galaxies. 

You certainly can but it's more challenging.  So, for someone starting out I'd suggest to keep things easy and work your way up from there.

 

As others have posted, image processing is a big piece, particularly if imaging from light polluted skies, in order to get reasonable results.

Imaging from a dark sky site is easier but even then, IMHO image processing plays an important role.

 

Suggest you share some results for us to help you further.

 

John



#10 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:14 PM

lol.gif Wow, four others posted while I was writing and posting.

I agree with alot of what's been posted here, some great advice.



#11 BigE

BigE

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 26 Mar 2020

Posted 07 August 2020 - 04:15 PM

Here is the .tif file... Thank you all...

 

Here is the Link to Google Drive and the file...

 

https://drive.google...ew?usp=sharing 


Edited by BigE, 07 August 2020 - 04:17 PM.

  • John O'Grady likes this

#12 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:17 PM

By the way, the reason I suggested a globular cluser is that it will be very apparent if it is in the field or not.

At your focal lenght it will be quite obvious. If aiming is playing a contributing role to the problem you are having it should help you quickly trouble shoot an aiming related problem.

 

John


Edited by John O'Grady, 07 August 2020 - 04:20 PM.


#13 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:18 PM

Here is the .tif file... Thank you all...

 

Here is the Link to Google Drive and the file...

 

https://drive.google...ew?usp=sharing 

Hmmm, links not working for me.



#14 idclimber

idclimber

    Messenger

  • -----
  • Posts: 469
  • Joined: 08 Apr 2016
  • Loc: McCall Idaho

Posted 07 August 2020 - 04:18 PM

Link is not working for me either. 



#15 BigE

BigE

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 26 Mar 2020

Posted 07 August 2020 - 04:20 PM

How about this one...

 

https://drive.google...ew?usp=sharing 



#16 Ken Sturrock

Ken Sturrock

    Cardinal Ximenez (No one expects the Spanish Inquisition)

  • *****
  • Administrators
  • Posts: 9,212
  • Joined: 26 Sep 2009
  • Loc: Denver, CO

Posted 07 August 2020 - 04:27 PM

Unfortunately, you have picked a pretty darned complicated way to amuse yourself. If it was easy, though, everybody would do it and it would lose all appeal.



#17 alphatripleplus

alphatripleplus

    World Controller

  • *****
  • Moderators
  • Posts: 115,903
  • Joined: 09 Mar 2012
  • Loc: Georgia

Posted 07 August 2020 - 04:31 PM

Don't give up!

 

Here is a mono capture of M101 with a C6, using an ASI290MM mini for capture. Stack of 19 x  25sec subs, using ASILive EAA software:

 

M101_f3.9_Light_Stack_19frames_25sec_RS_Bin1_30.2C_gain300_2020-07-16_235146.jpg

 

Okay, the 290MM is a sensitive mono camera versus a DSLR,  I'm in Bortle 4 versus Bortle 8-9, and this is a noisy EAA-type capture with the C6 operating at f/3.9 and the 290MM operating at high gain. However,  the point is a C6 is capable of capturing M101 in a few minutes of exposure.

 

Edit: I used to live under Bortle 8 skies, and M101 was still doable, but not in 8 minutes total exposure as shown above.


  • calypsob likes this

#18 Ron (Lubbock)

Ron (Lubbock)

    Viking 1

  • -----
  • Posts: 909
  • Joined: 17 Aug 2012
  • Loc: Pittstown, NY

Posted 07 August 2020 - 04:31 PM

After several years of AP, I would not even photograph M101 from Bortle 8-9.  The result is going to be less than great even if you do everything right.  Start with a DSO that has higher surface brightness.  I recall having poor results on M101 from a Bortle 3 site when I first started out... light pollution gradients and color distortions everywhere.

 

Good targets to try right now from a light polluted site with your equipment include M11, M27, M39, M51, M57, and any globular cluster.  Save M101 for later, I think.


  • John O'Grady likes this

#19 Gipht

Gipht

    Vanguard

  • *****
  • Posts: 2,499
  • Joined: 12 Nov 2016
  • Loc: Prescott Valley, AZ.

Posted 07 August 2020 - 04:47 PM

Here is a quick attempt.  This is a crop of the lower center part of your photograph.

 

 

Attached Thumbnails

  • Capture.JPG

  • BinoGuy likes this

#20 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:51 PM

Deleted my earlier post - I had forgotten to apply the the STF using a histogram stretch.

Sorry about that.

 

John



#21 John O'Grady

John O'Grady

    Viking 1

  • *****
  • Posts: 503
  • Joined: 15 Nov 2009
  • Loc: Waterloo, ON CAN

Posted 07 August 2020 - 04:52 PM

Hopefully I got it right this time:

M101-stretch-cropped.jpg

 

John

 



#22 klaussius

klaussius

    Viking 1

  • *****
  • Posts: 707
  • Joined: 02 Apr 2019
  • Loc: Buenos Aires

Posted 07 August 2020 - 04:53 PM

I get something similar.

 

There are weird concentric gradients that look like some kind of reflection, or an issue with flats overcorrecting at times.

 

m101_abr.jpg

 

How did you take your flats?

 



#23 meegja

meegja

    Mariner 2

  • -----
  • Posts: 200
  • Joined: 02 Jul 2020
  • Loc: The Netherlands

Posted 07 August 2020 - 05:27 PM

Here Photoshop too and I get the same as Klaussius and a tiny hint of M101 is visible.

I think the big circular ripple effect is because of wrong or no lens profile corrections before stacking. I don't know how it works though, I only did read about it.



#24 BigE

BigE

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 26 Mar 2020

Posted 07 August 2020 - 05:44 PM

First ... Thank you all... Any and all input is appreciated...

 

John,

I think that second thumbnail is actually Great ! as far as I'm concerned … 

Would you mind in a step by step tell me exactly how you got that image ?  If I could

duplicate that I would happy for now... 

 

Klaussius,

The flats were taken using a t-shirt and a light tablet, lowest dim.

The histogram came to about midway.

1/3 sec. and ISO400



#25 klaussius

klaussius

    Viking 1

  • *****
  • Posts: 707
  • Joined: 02 Apr 2019
  • Loc: Buenos Aires

Posted 07 August 2020 - 06:19 PM

Klaussius,

The flats were taken using a t-shirt and a light tablet, lowest dim.

The histogram came to about midway.

1/3 sec. and ISO400

 

It's important that you take excellent flats. With the amount of light pollution you have, any imperfection in the flats will cause similar weird gradients. It may not be your issue (it could also be a reflection), but you'll have to experiment a bit to find out what's wrong.

 

So, a few healthchecks on your flat "form":

  • Does the table cover the whole apperture?
  • Did you hold the tablet flush (perpendicular) to the apperture and steady?
  • Did you make sure there were no wrinkles in the t-shirt? You can replace the t-shirt with tracing paper, I find it works well.

Take a few flats and stretch them in PS to see its features. See if you can make those ripples in there. Do the same with an unprocessed light sub (a single one), in case it's a reflection or light leak.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: astrophotography



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics