#21  
Old 16-02-2010, 08:47 PM
Bassnut's Avatar
Bassnut (Fred)
Narrowfield rules!

Bassnut is offline
 
Join Date: Nov 2006
Location: Sydney
Posts: 4,772
Ahh Alex, you put up a good fight, but really, for most, the OAGer is just the work of the devil, EVIL no less, its a hatefull device to confound the keen. For anything under 2m FL, you have to be very methodical and tech-excited to bother, admit it. I found a hard bolted guide scope at less than 2m/20min exposures a joy to use, finding a guide star was a no brainer=more imaging fun.
Reply With Quote
  #22  
Old 16-02-2010, 08:52 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
The rig sounds beautiful mate Do you know the model number of this generator? Sounds exactly what I need...

That's the upside of being a holden man... I can fit just about anything in my commodore... I'd find a way to fit a PME + 12" OTA in there if I had to... Forgo the esky/food, just take a slingshot, knife and fork ahahaha.

Give the FOV indicator a go, it will give you a better idea of where a star will be. The only downside I have to my OAG at the moment is that field curvature means that some of the stars in the OAG are not round.. This results in odd guiding... That was the advantage of the ZS70 piggybacked on top, guide stars were VERY sharp, guider focus was independent of imaging focus (which changes from filter to filter ) I would only go back to a separate guide scope now if it had a slightly longer focal length than my 80/480... just to push the resolution of the guider a but further above the imaging setup... I figure if I get the guider going at around 1" per pixel, and get guiding corrections down to 0.3 pixels, then my imaging setup at 2.32" per pixel should be razor sharp. Thats the theory anyway Problem there is weight... The HEQ5 is limited to 17kgs according to the spec sheet, which means that in reality, its more like 12kgs, I want to stay at a max of 8kgs on the HEQ5, and maybe take it out to 10kgs on the GM8..
Reply With Quote
  #23  
Old 16-02-2010, 08:56 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Hah Fred. I admit... For most, the OAG is more of a pain than a pleasure. Especially at the longer focal lengths.. For my super wide field work, its a breeze...

Agreed, when I get back to a real man's telescope (2m+ FL) I'll be going to a solid mounted guide scope... Unless I manage to scrounge up the money for a real mans camera too... mmm ST10XME/CFW10/RGH/MOAG/AO-8 -- Droool..
Reply With Quote
  #24  
Old 16-02-2010, 09:01 PM
marki's Avatar
marki
Waiting for next electron

marki is offline
 
Join Date: Mar 2008
Posts: 2,427
Quote:
Originally Posted by AlexN View Post
The rig sounds beautiful mate Do you know the model number of this generator? Sounds exactly what I need...
This is the one.

http://www.hondagenerators.com.au/in...id=12&Itemid=9

Bit pricey but comes with a 5 year guarantee, can be coupled with another one to give 2kw output and has a built in 12 V battery charging function. It weighs bugger all, is really small and is so quiet you can have a normal conversation with it running right next to you. I love it . What filters are you using??? My astronomic filters are ace, no fiddling with focus between shots for me.

Mark
Reply With Quote
  #25  
Old 16-02-2010, 09:40 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Astrodon I series 50mm unmounted jobs...

What other refractive elements do you have in your optical train apart from the filters and the telescope lens? I think the MPCC I use to flatten the field skews the parfocalism (is that a word?) Either that or the LPS filter? or a combination of both...
Reply With Quote
  #26  
Old 16-02-2010, 09:49 PM
DavidU's Avatar
DavidU (Dave)
Like to learn

DavidU is offline
 
Join Date: Jul 2007
Location: melbourne
Posts: 4,719
That's a great little generator. Just the ticket for me.
Reply With Quote
  #27  
Old 16-02-2010, 09:49 PM
marki's Avatar
marki
Waiting for next electron

marki is offline
 
Join Date: Mar 2008
Posts: 2,427
Quote:
Originally Posted by AlexN View Post
Astrodon I series 50mm unmounted jobs...

What other refractive elements do you have in your optical train apart from the filters and the telescope lens? I think the MPCC I use to flatten the field skews the parfocalism (is that a word?) Either that or the LPS filter? or a combination of both...
None on the refractor but am considering a APM flattener, AP CCDT67 on the LX 200. I do get some reflection on the HH neb but the filters do not need refocusing between shots. Basically set autosave in maxim and off it goes. I have run them all through using a bahtinov mask and they are sweet. Thats one of astronomiks selling points, they guarantee the filters are all the same thicknes to within some ridiculous tolerence. They even have a go at other manufacturers over this and state it is their main reason for existence if you read one of the intro pages/company profile????

Mark
Reply With Quote
  #28  
Old 16-02-2010, 09:56 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
I've not used a bahtinov mask to check mine out, But I have just focused the L filter and ran 1x 5min L, R, G, B, S, H, O frames... the FWHM's for each filter are different.. L G are within 0.05 FWHM of each other, So I'd assume they are the same, R is .9 FWHM higher, B is 1.1 FWHM higher The NB filters are lower (due to being NB filters) but are all significantly (> 0.1 FWHM) different from each Other...

I will try the setup without the MPCC to see how that goes for parfocalisim...

The literature says they are parfocal down to F/4 optical systems. The literature also says 0 reflections, which I'm happy to say seems true in my setup.
Reply With Quote
  #29  
Old 16-02-2010, 10:01 PM
marki's Avatar
marki
Waiting for next electron

marki is offline
 
Join Date: Mar 2008
Posts: 2,427
I think my reflection comes from the glass on the nose piece of the camera but I am not taking it off to find out. I have only seen it on the HH but I quite like the effect it has on the HH panorama in any case. You are not chasing the seeing are you? I put little stock in the FWHM values as they really seem a bit random at times and I just use the mask now.

Mark
Reply With Quote
  #30  
Old 16-02-2010, 10:52 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Nah, its obvious in the frames too.. the focus shifts between filters... With a colour camera, RGB stars are focused equally, and there is no halo's around stars at all... If I don't refocus between RGB filters I end up with violet halo's due to R and B being out of focus and L and G focusing at the same point.
Reply With Quote
  #31  
Old 17-02-2010, 12:26 AM
marki's Avatar
marki
Waiting for next electron

marki is offline
 
Join Date: Mar 2008
Posts: 2,427
Quote:
Originally Posted by AlexN View Post
Nah, its obvious in the frames too.. the focus shifts between filters... With a colour camera, RGB stars are focused equally, and there is no halo's around stars at all... If I don't refocus between RGB filters I end up with violet halo's due to R and B being out of focus and L and G focusing at the same point.
Something is bending the light, you will have to go through bit by bit until you find it I guess. I am at a loss to think why thats for sure asumming you had the corrector setup at exactly the same distance with the OSC it could only be the filters. Could the smaller pixels better show a slightly uneven focal point that did not show on the bigger OSC pixels . Are your filters seated at exactly the same depth in the carousel? Dont know really.

Mark
Reply With Quote
  #32  
Old 28-02-2010, 08:13 AM
BlueAstra (Graham)
Registered User

BlueAstra is offline
 
Join Date: Dec 2009
Location: Manchester, UK
Posts: 44
This is my experience with an Orion OAG on a Celestron C8:

http://stargazerslounge.com/equipmen...rst-light.html

I've not had a problem finding guide stars, but I think that is due to the high sensitivity of the Lodestar guidecam.
Reply With Quote
  #33  
Old 28-02-2010, 02:10 PM
AlexN's Avatar
AlexN
Tunnel Vision

AlexN is offline
 
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Graham - Welcome to Ice In Space

I agree completely.. The Lodestar is a brilliant guide camera and is definitely at home in an OAG!

I'd really like to get a Lodestar..
Reply With Quote
  #34  
Old 28-02-2010, 09:22 PM
Paul Haese's Avatar
Paul Haese
Registered User

Paul Haese is offline
 
Join Date: Jan 2009
Location: Adelaide
Posts: 9,403
Imaging with a OAG is certainly new for me. I have tried so many times with several versions but failed to get good results, until relatively recently.

I had obtained reasonable results with a guide scope but there was always some tiny amount of flexure. With the OAG this is not the problem it is just the guiding settings that needs sorting out. That is where the evil seems to be.

Certainly a black art and I am trying to master this myself. An interesting thread guys.
Reply With Quote
  #35  
Old 03-03-2010, 06:17 PM
marki's Avatar
marki
Waiting for next electron

marki is offline
 
Join Date: Mar 2008
Posts: 2,427
Just recieved my M48 adapter for the TS OAG-9. Must say it's looking a lot better then the T2 version (37 Vs 47mm clear aperture). Still cant rotate much but at least there is less of a bottleneck in front of the FW.


Mark
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 08:57 PM.

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