Go Back   IceInSpace > Equipment > Astrophotography and Imaging Equipment and Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 30-12-2013, 04:42 PM
Paul Haese's Avatar
Paul Haese
Registered User

Paul Haese is offline
 
Join Date: Jan 2009
Location: Adelaide
Posts: 9,276
This is how guiding should be all the time

I often get good guiding at Clayton, but forget how good it really is until someone reminds me of what I have here. The sub arc seeing here really helps with all imaging including planetary and DSO work.

For those that don't often see good seeing with good guiding I thought I would supply you with an image of a guide graph and the guide corrections being made in MaximDL during an imaging run last night.

Feel free to add you own experiences of your guiding; good bad or otherwise.
Attached Thumbnails
Click for full-size image (guide graph.jpg)
142.7 KB357 views
Reply With Quote
  #2  
Old 30-12-2013, 05:09 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,581
Looks nice and flat, Paul! What's your guider image scale? I presume the graph units are pixels, not arc seconds?

Cheers,
Rick.
Reply With Quote
  #3  
Old 30-12-2013, 05:14 PM
Paul Haese's Avatar
Paul Haese
Registered User

Paul Haese is offline
 
Join Date: Jan 2009
Location: Adelaide
Posts: 9,276
Using the ST-I with an OAG on a system at 580mm at f5.6. I think that is somewhere around 1.89" per pixel or close to that. The later figure is the scale of the QSI/ TSA with reducer.
Reply With Quote
  #4  
Old 30-12-2013, 07:31 PM
Logieberra's Avatar
Logieberra (Logan)
Registered User

Logieberra is offline
 
Join Date: Mar 2010
Location: Canberra
Posts: 1,543
Paul, have you toyed with the idea of using direct guide of your paramounts via TheSkyX? Just wondering why Maxim. A case of, works well, ain't broke so don't fix it?
Reply With Quote
  #5  
Old 30-12-2013, 07:58 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,581
RMS around 0.2 arc sec is quite respectable
Reply With Quote
  #6  
Old 30-12-2013, 08:14 PM
Astroman's Avatar
Astroman (Andrew Wall)
<><><><>

Astroman is offline
 
Join Date: Feb 2005
Location: Paralowie, South Australia
Posts: 4,348
Nice work Paul. The seeing lastnight was okay up here, with exception of all the LP, but you get that. But I noticed in the small time I had my guiding working, it was really smooth also, it wasn't jumping around at all.
Reply With Quote
  #7  
Old 30-12-2013, 08:18 PM
LewisM's Avatar
LewisM
Novichok test rabbit

LewisM is offline
 
Join Date: Aug 2012
Location: Somewhere in the cosmos...
Posts: 8,903
I know my setup is VERY small in comparison, but my Vixen GPD2 pushing the FL102S with a Lodestar guider (using a Tak finder as guidescope rigidly mounted to the main tube), and using an SBIG ST-8XE cam, I can set and forget all night. I can not even hear the guide correction pulses etc (IF I do a GOOD polar alignment, which is always - I will not do an imaging run with a mean Alt or Az error in excess of 10 seconds out in each). I have had cloud come over and block the target for 7 minutes - the guide program just instantly locked back on when clear, since the star had been tracked PERFECTLY the entire time.

My graphs in MaxIM are VERY similar to yours Paul. Same in PHD, if/when I use it, but I find PHD guiding NOT as smooth as MaxIM's which seems to send VERY smooth, very short corrections.

I am always delightedly chuffed to see perfectly round stars across the FOV. It's one of those little joys in imaging. I keep telling myself I don't have aperture fever because that would mean most likely going up to the next mount, which I do NOT want to do considering how darned well this system seems to work.

Now if only I had a clue how to process all that data properly. THAT would be a god-send
Reply With Quote
  #8  
Old 30-12-2013, 11:05 PM
ericwbenson (Eric)
Registered User

ericwbenson is offline
 
Join Date: Sep 2009
Location: Adelaide, Australia
Posts: 196
Quote:
Originally Posted by Paul Haese View Post
Using the ST-I with an OAG on a system at 580mm at f5.6. I think that is somewhere around 1.89" per pixel or close to that. The later figure is the scale of the QSI/ TSA with reducer.
Hi Paul,
That OAG is working at 2.7"/pixel (206*7.4/580), so the guiding RMS is about 0.3", which is ok but nothing spectacular. However the seeing might actually be very good since at that short focal length the centroid precision is limited to around 0.3ish arcsec (1/10th of a pixel), so the guider noise you are recording could be really just centroid noise, you can't really tell. Of course it's academic for the main image which is also at ~ 2"/pix.

Best
EB
Reply With Quote
  #9  
Old 30-12-2013, 11:42 PM
strongmanmike's Avatar
strongmanmike (Michael)
Woohoo it's clear

strongmanmike is offline
 
Join Date: May 2006
Location: Canberra
Posts: 14,455
Quote:
Originally Posted by Paul Haese View Post
The sub arc seeing here really helps.
You really get sub arc sec seeing??? You sure? Do you mean sub arc sec seeing for moments or for extended periods? Sub arc sec seeing for extended periods is the stuff of places like La Palma/Cerre Tololo etc...? Even Siding Spring rarely gets sub arc sec seeing

The tracking looks good though

Mike
Reply With Quote
  #10  
Old 31-12-2013, 01:10 AM
Shiraz's Avatar
Shiraz (Ray)
Registered User

Shiraz is offline
 
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,785
looks nice Paul - better than 1 arc sec peak to peak guiding noise is certainly good.
as others have pointed out, Australian seeing is definitely not up there with the best - I find that it doesn't normally get much better than about 2 arc sec where I am (sea level). If of any interest, data from Siding Springs and the Flinders Ranges (fairly close to Eric's system) shows that zenith seeing much below an arc sec is pretty hard to come by, even at elevated Australian sites. regards Ray
http://www.southerngalactic.com/Arka...dersRanges.pdf

Last edited by Shiraz; 31-12-2013 at 01:26 AM.
Reply With Quote
  #11  
Old 31-12-2013, 02:16 AM
Screwdriverone's Avatar
Screwdriverone (Chris)
I have detailed files....

Screwdriverone is offline
 
Join Date: Feb 2008
Location: Kellyville Ridge, NSW Australia
Posts: 3,306
Looks Nice Paul,

I can only wish for results like that.

I feel like smashing this setup. Currently imaging Eta Carina. BUT, after drift aligning at least 3 times and getting a fairly flat PHD graph (even with pretty much SFA drift) I am getting some sort of SW drift in every second image????

Here is a pic of the garbage I am seeing now. Almost the entire night is a write off, I am not sure if it is balance or alignment or levelling or all three?

I seriously need to pull the finger out and install the pier and build the freaking obs, this portable garbage wastes soooooo much of my time and sanity and gives absolutely bull crap inconsistent results it makes me want to take to it with a baseball bat.

There. Rant over. Back to see if eggs are on the menu with my latest sub......

Cheers

Chris
Attached Thumbnails
Click for full-size image (crap guiding.JPG)
177.8 KB135 views
Reply With Quote
  #12  
Old 31-12-2013, 12:38 PM
rat156's Avatar
rat156
Registered User

rat156 is offline
 
Join Date: Aug 2005
Location: Melbourne
Posts: 1,653
Hi All,

Seeing in Melbourne suburbs is pretty crap pretty much most of the time, my FWHM varies between 2 and 4 arc seconds, or pixels, as I image at about 1"/pixel.

I can only dream of sub-arcsecond seeing.

Still you can achieve nice pictures with heaps of detail even with crappy seeing. Narrowband imaging helps for nebulae, but not so much for galaxies, though except for some of the very bright ones, I've pretty much given up on galaxies, too much light pollution.

Cheers
Stuart
Reply With Quote
  #13  
Old 31-12-2013, 12:48 PM
Peter.M's Avatar
Peter.M
Registered User

Peter.M is offline
 
Join Date: Sep 2011
Location: Adelaide
Posts: 914
Quote:
Originally Posted by Screwdriverone View Post
I seriously need to pull the finger out and install the pier and build the freaking obs, this portable garbage wastes soooooo much of my time and sanity and gives absolutely bull crap inconsistent results it makes me want to take to it with a baseball bat.

Get an OAG and all your problems will dissappear, good guide graph and then eggy stars means diff flex! I set up each night aswell, and when I was using a guidescope things were inconsistent. I wacked an OAG in the train and since then I can expose for as long as I want and get round stars.
Reply With Quote
  #14  
Old 31-12-2013, 05:38 PM
TR's Avatar
TR (Terry)
Registered User

TR is offline
 
Join Date: Jul 2011
Location: Melbourne, Australia
Posts: 161
Ok, here is my graph from Melbourne Central. Mount helps a lot but no sub arc second seeing here. Need a special mountain top for that. That's my standard automation quick view.

Terry
Attached Thumbnails
Click for full-size image (WorkingEnviroment_Observatory.jpg)
209.7 KB107 views
Reply With Quote
  #15  
Old 01-01-2014, 08:25 AM
stevous67 (Steve M)
Registered User

stevous67 is offline
 
Join Date: Jul 2008
Location: Melbourne, Australia
Posts: 633
Quote:
Originally Posted by TR View Post
Ok, here is my graph from Melbourne Central. Mount helps a lot but no sub arc second seeing here. Need a special mountain top for that. That's my standard automation quick view.

Terry
Very nice overview Terry.

Steve
Reply With Quote
  #16  
Old 01-01-2014, 09:35 AM
rat156's Avatar
rat156
Registered User

rat156 is offline
 
Join Date: Aug 2005
Location: Melbourne
Posts: 1,653
Quote:
Originally Posted by TR View Post
Ok, here is my graph from Melbourne Central. Mount helps a lot but no sub arc second seeing here. Need a special mountain top for that. That's my standard automation quick view.

Terry
Hi Terry,

Wow, that's quite tight guiding, what's the guider image scale?

I find, just watching the guide errors on the PMX that mostly the guide error is below 1.5 pixels (which works out to 3 pixel p-p, which is what the seeing generally is around here). I have found that short exposure, rapid guiding leads to poor guiding, whereas about 2-3 second exposures and setting the minimum move to .3 pixel smooths everything out nicely. I still end up with slightly elongated stars sometimes, but it's usually a focus issue.

I'm always looking for better guiding though.

Cheers
Stuart
Reply With Quote
  #17  
Old 01-01-2014, 01:56 PM
Screwdriverone's Avatar
Screwdriverone (Chris)
I have detailed files....

Screwdriverone is offline
 
Join Date: Feb 2008
Location: Kellyville Ridge, NSW Australia
Posts: 3,306
Quote:
Originally Posted by Peter.M View Post
Get an OAG and all your problems will dissappear, good guide graph and then eggy stars means diff flex! I set up each night aswell, and when I was using a guidescope things were inconsistent. I wacked an OAG in the train and since then I can expose for as long as I want and get round stars.
Hmmm, thanks Peter, that makes quite a lot of sense....!

I find that the long tube BD200N / Orion Miniguidescope / HEQ5 Pro combination behaves very differently depending on the position it is pointing, which is why I have to relearn PHD for each target. Then, as you say, even with a flat line PHD graph, I get rubbish results with my stars.

I am having a look at the slimline Orion OAG as an option for my rig.

Thanks for the info, hopefully this could sort it out.

Cheers

Chris
Reply With Quote
  #18  
Old 01-01-2014, 02:15 PM
TR's Avatar
TR (Terry)
Registered User

TR is offline
 
Join Date: Jul 2011
Location: Melbourne, Australia
Posts: 161
Hi Stuart,

My rig is a modified Vixen R200SS with a Televue Paracorr Type 2 corrector. The focal length is now 920mm / Focal ratio 4.6. The Paracorr increases the focal length from its native 4.0. The main CCD is a first generation SBIG ST-8300 mono – with a pixel size 5.4 microns. My image scale is around 1.2. I have milled the spider down to 1.7 mm and have installed a secondary heater. Funky white wires, they are 1.5 mm thick.

The guide scope is an Orion 50mm (162 mm fl) with a SBIG ST-i stuck in there. In the photo, you can see a block of carbon fibre I made that has the same radius as the Optical tube and is bolted directly to the optical tube. The guide scope is pulled into an inverted aluminium channel on the block via stainless steel hose clamp. There is no adjustment and the whole assembly it is literally part of the optical tube now. It moves with the scope – it has to. There is no flexing within its tube rings, or where the main scope mounts to the dovetail as it is literally bonded to the main optical tube. The stock focuser has been adjusted to remove any movement that I could detect by running results via CCD Inspector looking for flex in altitude changes.

The focuser is a Rigel Systems NStep focuser, focusing controlled via FocusMax. It works. Each step is 3.14 microns on my system. The stepper is strong, and has no issues lifting the camera.

Mount is an AP-900. This is really the best part of the system. It has never given me any issues, it just works.

On the back of the scope is a Mount Hub Pro. It’s convenient, but often requires a bit of coxing. I have never been able to run VB Scripts to control Ascom stuff – like turning on and off of cameras, heaters, fans, via scripting. I should add that this can be done with the Mount Hub Pro control program on the PC, unfortunately, not via scripting under windows 8 – 64 bit. I would love to be able to turn everything off via a script after an imaging run.

I image from the city, and if the conditions are right, head out to a dark place.

Terry
Attached Thumbnails
Click for full-size image (GuideCamera.jpg)
181.6 KB72 views
Reply With Quote
  #19  
Old 01-01-2014, 03:10 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,106
That's great Paul. It sounds like you have great conditions. I know you are an expert in seeing from your planetary experience where its everything.

Of course guide errors are much smaller when using a short focal length. Longer focal length shows up errors much better. You see smaller guide errors with shorter focal length scopes.

I am not sure about this seeing measurement myself. FWHM seem to be a guide only. Good seeing is easily seen in the image given good focusing. I think that is one of the main criteria for measuring. FWHM values vary significantly in the same image on different stars. At least using CCDstack. So I don't know how anyone can come up with a FWHM number that is meaningful as it is more a variable than a fixed item.

Greg.
Reply With Quote
  #20  
Old 01-01-2014, 04:42 PM
rat156's Avatar
rat156
Registered User

rat156 is offline
 
Join Date: Aug 2005
Location: Melbourne
Posts: 1,653
Quote:
Originally Posted by TR View Post
Hi Stuart,

snip

The guide scope is an Orion 50mm (162 mm fl) with a SBIG ST-i stuck in there. In the photo, you can see a block of carbon fibre I made that has the same radius as the Optical tube and is bolted directly to the optical tube. The guide scope is pulled into an inverted aluminium channel on the block via stainless steel hose clamp. There is no adjustment and the whole assembly it is literally part of the optical tube now. It moves with the scope – it has to. There is no flexing within its tube rings, or where the main scope mounts to the dovetail as it is literally bonded to the main optical tube. The stock focuser has been adjusted to remove any movement that I could detect by running results via CCD Inspector looking for flex in altitude changes.

snip
Terry
Hi Terry,

According to my calculations that works out to be 9.4"/pixel for your guiding, is this correct?

Cheers
Stuart
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 02:27 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Lunatico Astronomical
Advertisement
Meade Australia
Advertisement
OzScopes Authorised Dealer
Advertisement
NexDome Observatories
Advertisement
SkyWatcher Australia
Advertisement
Bintel
Advertisement
Celestron Australia
Advertisement
Astronomy and Electronics Centre
Advertisement