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

Manual Guiding

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

#1 GRC

GRC

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 28 Jan 2020
  • Loc: Idaho

Posted 01 June 2020 - 02:39 PM

Hi, I have an old Nexstar 4GT set up on an equatorial wedge and it doesn't track nearly good enough for astrophotography. Is it possible to manually keep a star centered in a guide scope and get reasonable images?



#2 freddie

freddie

    Vostok 1

  • -----
  • Posts: 127
  • Joined: 26 Oct 2010

Posted 01 June 2020 - 02:52 PM

Depends on your personal definition of reasonable.



#3 astrodom

astrodom

    Mariner 2

  • -----
  • Posts: 203
  • Joined: 04 Jan 2008
  • Loc: NY , USA

Posted 01 June 2020 - 03:12 PM

 I have done manual guiding in the old days before autoguiding was popular.  The problem is you are imaging at over 1000mm and you would probably need an off axis guider for your manual guiding.   It might be a challenge to do in a reproducible manner, but sometimes experimenting can lead to some surprises. :-)



#4 Stelios

Stelios

    Cosmos

  • *****
  • Moderators
  • Posts: 9,241
  • Joined: 04 Oct 2003
  • Loc: West Hills, CA

Posted 01 June 2020 - 03:32 PM

You should be able to find an old guide cam for well under $100. Unless your time is worth nothing to you, I'd think that's the way to go. 



#5 GRC

GRC

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 28 Jan 2020
  • Loc: Idaho

Posted 01 June 2020 - 04:36 PM

You should be able to find an old guide cam for well under $100. Unless your time is worth nothing to you, I'd think that's the way to go. 

The reason I am not thinking about auto guiding is because the mount is so old that I don't think the hand controller or the mount supports auto guiding.



#6 Alex McConahay

Alex McConahay

    Cosmos

  • *****
  • Posts: 9,102
  • Joined: 11 Aug 2008
  • Loc: Moreno Valley, CA

Posted 01 June 2020 - 04:41 PM

>>>>>>it doesn't track nearly good enough for astrophotography.

 

Depends on the reason it is not good enough for astrophotography and what your standards are. After all, people still use film and barn door trackers and get shots they can be proud of. 

 

If it is not tracking well enough because it is not polar aligned, or the gears are not properly adjusted----yeah, you can make improvements. 

 

If it is not tracking because the gears are torn up or were never up to it in the first place, then your eyeball and a good guide scope will not be enough to fix the problems. 

 

Of course, the poopiest tracking mount can get some images with very short exposures. 

 

Bottom line is that before the invention of the autoguiding system many imagers used to manually track their mounts. I remember a story of one of the astronomers on Mt. Wilson doing that with the 100 inch. So, it can be done. Whether you will be happy with it is another question. 

 

Alex



#7 GRC

GRC

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 28 Jan 2020
  • Loc: Idaho

Posted 01 June 2020 - 04:49 PM

Depends on your personal definition of reasonable.

I am aiming for about 30 sec exposures to start with. I am able to tolerate slightly football shaped stars.



#8 klaussius

klaussius

    Viking 1

  • *****
  • Posts: 521
  • Joined: 02 Apr 2019
  • Loc: Buenos Aires

Posted 01 June 2020 - 05:12 PM

I am aiming for about 30 sec exposures to start with. I am able to tolerate slightly football shaped stars.

You can totally do that, I did it for a while at 750FL. But as Stelios said, it's time consuming, exhausting and literally, physically painful (esp in cold weather). A cheap guide cam is worth every buck spent on it.

 

Though from what I can see, the Nextstar 4 lacks an autoguide port. That's not good.


Edited by klaussius, 01 June 2020 - 05:18 PM.


#9 StephenW

StephenW

    Apollo

  • -----
  • Posts: 1,037
  • Joined: 04 Feb 2005
  • Loc: San Jose, CA

Posted 01 June 2020 - 05:19 PM

What are you planning to image and guide with (guide scope, OAG?)

 

I actually played about with "manually" guiding my mount when running some tests on it's performance - I still used my OAG and guide cam, which gave me a nice zoomed image of the guide star on my laptop screen.  Using the mount's controller to nudge the guide star and keep it centered wasn't too difficult, and was able to do it all from a comfortable chair.

 

I certainly wouldn't recommend the old method of physically looking through a guide-scope or OAG  - not unless you are setting aside money for physio/chiro to sort out your neck/back afterwards... :)



#10 Madratter

Madratter

    Voyager 1

  • *****
  • Posts: 12,448
  • Joined: 14 Jan 2013

Posted 01 June 2020 - 06:17 PM

It might be doable, but whether it will meet your expectations is up to you. Part of why it was doable with film is that film grain is typically quite large (15 microns and up for B&W, 10 & up for color). Most films it was up (i.e. not on the smaller side). Contrast that to digital cameras with pixel sizes that are often somewhere between 2 and 6 microns. In other words, modern cameras will show defects that weren't as important with film.


  • bobzeq25 likes this

#11 GRC

GRC

    Lift Off

  • -----
  • topic starter
  • Posts: 8
  • Joined: 28 Jan 2020
  • Loc: Idaho

Posted 02 June 2020 - 10:41 AM

You can totally do that, I did it for a while at 750FL. But as Stelios said, it's time consuming, exhausting and literally, physically painful (esp in cold weather). A cheap guide cam is worth every buck spent on it.

 

Though from what I can see, the Nextstar 4 lacks an autoguide port. That's not good.

Looks like I may want to think about getting a GEM with autoguide capabilities.


  • Madratter likes this


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