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

Reply
 
Thread Tools Rate Thread
  #21  
Old 05-11-2011, 10:11 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Now I'm looking at this scope (CT8)...
http://www.orionoptics.co.uk/CT/ctra...28ota%29t.html
...after seeing this image done with a Cooled 50D...
http://apod.nasa.gov/apod/ap110804.html
...and it's in my price range.
Thoughts??

Cheers
Doug

ps...yes, I know it's not a refractor!!
Reply With Quote
  #22  
Old 06-11-2011, 05:26 AM
gbeal
Registered User

gbeal is offline
 
Join Date: Oct 2004
Location: New Zealand
Posts: 4,299
Well Doug, if you are jumping ship, and looking at a newt, the AstroTech 8" imaging newt onion I had would be perfect, and even better if you can find a C/F tube for it. BUT......... be prepared to tinker a bit with the mechanics to make it work as it should. The Orion Optics ones might/should be better, and not need too much tinkering hopefully, plus the CF tube would reduce the wight a lot. Skywatcher are also bringing in CF newt tubes, so check them.
The one thing that got up my nose the most and caused me to revert to the refractor was the required collimation. Maybe I was inept, or maybe mine just needed more than most, but there was nothing worse that thinking it was right, and launching into a series of deep and dark, to find it wasn't. I quickly tired of that. Others swear by them, I ended up swearing at it. As our American friends so succinctly put it, YMMV.
Gary
Reply With Quote
  #23  
Old 06-11-2011, 08:28 AM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gbeal View Post
Well Doug, if you are jumping ship, and looking at a newt, the AstroTech 8" imaging newt onion I had would be perfect, and even better if you can find a C/F tube for it. BUT......... be prepared to tinker a bit with the mechanics to make it work as it should. The Orion Optics ones might/should be better, and not need too much tinkering hopefully, plus the CF tube would reduce the wight a lot. Skywatcher are also bringing in CF newt tubes, so check them.
The one thing that got up my nose the most and caused me to revert to the refractor was the required collimation. Maybe I was inept, or maybe mine just needed more than most, but there was nothing worse that thinking it was right, and launching into a series of deep and dark, to find it wasn't. I quickly tired of that. Others swear by them, I ended up swearing at it. As our American friends so succinctly put it, YMMV.
Gary
Keeping my options very much open Gary.
I do remember with dread all the collimation fuss involved with my old 12" dob every time I merely nudged the damn thing.
Also, the added weight would necessitate a mount upgrade too - an expense I don't need.
I contacted Maximo Ruiz who took that lovely NGC 7023 APOD with this scope and he has upgraded the focuser too - $$$!!!

"Lord you know it ain't easy..."

Doug
Reply With Quote
  #24  
Old 06-11-2011, 08:34 AM
gbeal
Registered User

gbeal is offline
 
Join Date: Oct 2004
Location: New Zealand
Posts: 4,299
Don't let me pour cold water on the thought, the humble newt reigns supreme as bang for buck, and especially in imaging. BUT....... the tinkering required takes a fair bit of fun out of the whole shebang.
Unless you opt for the TMB92 WITH the F/T I reckon you are headed to a focuser upgrade anyway, sorry.
Gary
Reply With Quote
  #25  
Old 06-11-2011, 09:54 AM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gbeal View Post
Unless you opt for the TMB92 WITH the F/T I reckon you are headed to a focuser upgrade anyway, sorry.
Gary
Agreed - contacted Starlight re a replacement focuser for the TMB92L. They recommended a 2.5" model + relevant adapter which all up would be $820US. There's a 3" FT model on the 92SS anyway so the 'buy cheap and upgrade' route looks redundant.
Reply With Quote
  #26  
Old 07-11-2011, 06:35 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,409
My opinion is for imaging an 8 inch Newt with high grade optics and a carbon fibre tube like you are looking at would be far more capable than a 92mm APO. To my eye Newt images are very pleasing and very tight stars. I would be concerned 92mm may be just a tad not enough aperture. I had a nice 80mm APO once but it really didn't have enough aperture. Would 92mm have enough? I don't know - have you seen a lot of images from one?

The downside to Newts are collimation, tube currents, coma, and flexures.

Collimation is a matter of having the right collimation gear.

You really want a fan. Carbon fibre is good as no expansion and light.
No expansion means the same focus spot night after night or at least very close
and it does not go off during the night.

Coma is a matter of having the right corrector.

Flexure - Newt seem a bit more likely to suffer from flexure as the focuser sticks out the side. I see a lot have the camera hanging down under the Newt no doubt to ease that sideways pressure.

But then when deciding on gear, I think you should work backwards from the type of image you most want to take and then work out what gear you would need to achieve that shot.

I used to have an 8 inch Vixen F4 newt as have a lot on this site. It was hard to collimate until I got a cheap Antares laser collimator and then it took 5 minutes!

There is also the 8 inch Boren Simon F2.8 imaging newt. I think they sell for around US$2500 or so. F2.8 may be a little touchy for collimation and flexure but it would also be amazingly fast.

Orion Optics UK make really good optics. Look at John's recent images with one.

Greg.
Reply With Quote
  #27  
Old 07-11-2011, 08:21 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gregbradley View Post
My opinion is for imaging an 8 inch Newt with high grade optics and a carbon fibre tube like you are looking at would be far more capable than a 92mm APO. To my eye Newt images are very pleasing and very tight stars. I would be concerned 92mm may be just a tad not enough aperture. I had a nice 80mm APO once but it really didn't have enough aperture. Would 92mm have enough? I don't know - have you seen a lot of images from one?

The downside to Newts are collimation, tube currents, coma, and flexures.

Collimation is a matter of having the right collimation gear.

You really want a fan. Carbon fibre is good as no expansion and light.
No expansion means the same focus spot night after night or at least very close
and it does not go off during the night.

Coma is a matter of having the right corrector.

Flexure - Newt seem a bit more likely to suffer from flexure as the focuser sticks out the side. I see a lot have the camera hanging down under the Newt no doubt to ease that sideways pressure.

But then when deciding on gear, I think you should work backwards from the type of image you most want to take and then work out what gear you would need to achieve that shot.

I used to have an 8 inch Vixen F4 newt as have a lot on this site. It was hard to collimate until I got a cheap Antares laser collimator and then it took 5 minutes!

There is also the 8 inch Boren Simon F2.8 imaging newt. I think they sell for around US$2500 or so. F2.8 may be a little touchy for collimation and flexure but it would also be amazingly fast.

Orion Optics UK make really good optics. Look at John's recent images with one.

Greg.
Thanks Greg - you've covered a lot of the bases in that description.

Orion Optics CT8 has built in fans which is a plus - from what I can glean from web searches, the OC1 stock focuser may be a weak point - looks the biz but isn't in reality. Haven't seen one in the flesh so I can't comment with any authority. Maximo Ruiz seems to make his CT8 sing that's for sure.

Re type of imaging: I think that a jump from widefield (400mm) to 900mm FL might challenge me to move on from the more commonly imaged targets - I think that would be a positive move for me. But, FSQ-type widefield images are the ones that appeal to me the most.
Their WOW factor is an addictive motivation for the pursuit of a sweet refractor.
As dilemmas go, it's a nice dilemma to have!
Reply With Quote
  #28  
Old 07-11-2011, 08:29 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,409
Re type of imaging: I think that a jump from widefield (400mm) to 900mm FL might challenge me to move on from the more commonly imaged targets - I think that would be a positive move for me. But, FSQ-type widefield images are the ones that appeal to me the most.
Their WOW factor is an addictive motivation for the pursuit of a sweet refractor.
As dilemmas go, it's a nice dilemma to have![/QUOTE]


FSQ images are among the most popular of all images for sure.

Refractor images to me are the most pure of images as no central obstruction, no diffractions spikes are those tight tiny stars make for very appealling images.

TMB92 may capture similar. Are there example images on the net you are aware of using that scope?

The TMB though isn't 900mm focal length. But you may be able to use a Tak 1.6 extender to make it about 825mm focal length and nearly F9.

I have used a Tak 1.6 extender on my TEC180 and it worked very well.

Greg.
Reply With Quote
  #29  
Old 07-11-2011, 08:50 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Greg - I was meaning the 900mm FL of the Orion Optics Newt.
The TMB is 506mm.
Doug
Reply With Quote
  #30  
Old 07-11-2011, 09:00 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gregbradley View Post

TMB92 may capture similar. Are there example images on the net you are aware of using that scope?
Alan Dyer reviewed it in S&T and has imaged with one...
http://amazingsky.photoshelter.com/s...=t&_ACT=search

It's a site to sell his images so the samples don't d/load to full res.
Star colour looks nice in some
Doug
Reply With Quote
  #31  
Old 08-11-2011, 07:29 AM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,409
I stand corrected, those TMB92mm images are quite nice. A but hard to see as they are so small but they look quite good.
That Borg reducer /flattener seems good to be able to handle a 5D11.

Greg.
Reply With Quote
  #32  
Old 08-11-2011, 08:23 AM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gregbradley View Post
I stand corrected, those TMB92mm images are quite nice. A but hard to see as they are so small but they look quite good.
That Borg reducer /flattener seems good to be able to handle a 5D11.

Greg.
Another gallery - many taken with TMB92SS and Astrotech Flattener.
Work backwards through gallery with an eye on the exif data...
http://buzzer.zenfolio.com/p52690309...a734#h161d3d5c

ps...had a look at the Boren-Simon f2.8. Images look fantastic, but $2.5k for a GSO 8" Newt and an ASA corrector is a tad excessive
Reply With Quote
  #33  
Old 08-11-2011, 10:24 AM
gbeal
Registered User

gbeal is offline
 
Join Date: Oct 2004
Location: New Zealand
Posts: 4,299
The 92 will fit your current mount (assume you have the HEQ5??) better than the 8" imaging newt. The one I had was quite heavy.
Gary
Reply With Quote
  #34  
Old 08-11-2011, 11:06 AM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by gbeal View Post
The 92 will fit your current mount (assume you have the HEQ5??) better than the 8" imaging newt. The one I had was quite heavy.
Gary
Agreed Gary - Newt+DSLR+extras weighs in at around 10kg. That's pushing the HEQ5 for imaging. I want to keep the weight as far under the 10kg mark as possible.
Reply With Quote
  #35  
Old 08-11-2011, 11:55 AM
Poita (Peter)
Registered User

Poita is offline
 
Join Date: Jun 2011
Location: NSW Country
Posts: 3,585
But then look at these images from a C8, http://www.flickr.com/photos/jasmel9...in/photostream and then look at these C14 images....
http://www.rodgerb.com/gallery_xxxi.htm

It isn't all that indicative of what you would expect to get out of those two scopes.

Some people are freakishly good with the gear they have, or happen to get ideal seeing where they live ,and get great images from just about anything.
If I could get that performance out of a C8 I'd sell my other gear tomorrow...

Point is, I think you will get better results and more detail with a 105 scope rather than a 92, and they will still be well weighted for your scope and you won't get aperture fever as quickly. Galleries are great to see what a scope can be capable of, but it isn't always much of an indication of the scope, more of the seeing, processing, skill and luck of the draw.

Quote:
Originally Posted by dugnsuz View Post
Another gallery - many taken with TMB92SS and Astrotech Flattener.
Work backwards through gallery with an eye on the exif data...
http://buzzer.zenfolio.com/p52690309...a734#h161d3d5c

ps...had a look at the Boren-Simon f2.8. Images look fantastic, but $2.5k for a GSO 8" Newt and an ASA corrector is a tad excessive
Reply With Quote
  #36  
Old 08-11-2011, 01:58 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Quote:
Originally Posted by Poita View Post
Point is, I think you will get better results and more detail with a 105 scope rather than a 92, and they will still be well weighted for your scope and you won't get aperture fever as quickly. Galleries are great to see what a scope can be capable of, but it isn't always much of an indication of the scope, more of the seeing, processing, skill and luck of the draw.
I'm still looking at the SV105 Peter - waiting for them to quote shipping to Oz.
Reply With Quote
  #37  
Old 08-11-2011, 03:53 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 15,409
That's an interesting point. What is better? Slightly larger aperture and good optics or smaller aperture and higher quality optics?

Not sure of the answer to that. I think I'd take larger optics over smaller if quality were similar. If one were way better then I'd chose slightly smaller over larger.

Keep in mind the % increase in aperture from 92 to 105 is significant.


Greg.
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 08:30 AM.

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