Go Back   IceInSpace > Equipment > Equipment Discussions

Reply
 
Thread Tools Rate Thread
  #1  
Old 08-03-2019, 05:33 PM
hpgregory (Harrison)
Registered User

hpgregory is offline
 
Join Date: Mar 2019
Location: Launceston
Posts: 2
Small Telescope vs Guider Scope. Over Payload Capacity?

I am currently looking to add an auto guiding function to my current setup. Current setup being:
- NEQ6 Mount
- SkyWatcher Black Diamond 250/1200 Dual Speed Photo Reflector
- Nikon D7200
I want to get into long exposure DSO imaging and am aware this usually requires a guider of some sort. Also hoping that by using PHD (or similar) I will be able to obtain a better polar alignment.

At the moment I have been looking at two possible scopes:
SkyWatcher 80/400 Achromatic Refractor
SkyWatcher Evoguide 50mm ED Guidescope
Originally I was looking at the refractor as it could be used as a small telescope, its larger focal length and the clamps that came with it. However, I have been told that this may be adding to much weight onto my mount and was suggested the Evoguide instead. I am not sure if the FL would be enough and also concerned about the attachment system as I have heard this type can be prone to flexure. As a beginner I am unsure how big of a problem this is.

The guiding camera I have in mind is the ZWO ASI120MC-S USB3.0 Colour.

I would love any advice on this and apologies cause this question has probably been asked so many times before.
Reply With Quote
  #2  
Old 08-03-2019, 05:48 PM
skysurfer's Avatar
skysurfer
Dark sky rules !

skysurfer is offline
 
Join Date: Dec 2011
Location: 52N 6E (EU)
Posts: 1,150
Get an off-axis guider.
https://www.bintel.com.au/?s=off+axi...v=6cc98ba2045f
It allows you to use the main scope as a guidescope as well without comporomising the image quality, as the guide star is, as the name says, off-axis. It usually contains a 1.25" barrel which fits an eyepiece or an autoguiding camera.

Saves a lot of weight (and money).
Reply With Quote
  #3  
Old 08-03-2019, 10:47 PM
that_guy's Avatar
that_guy (Tony)
Local Korean Millennial

that_guy is offline
 
Join Date: Dec 2009
Location: Charleville
Posts: 2,041
yeah, at that focal length an OAG is probably your best bet. Reduces weight and flexure.
Reply With Quote
  #4  
Old 11-03-2019, 09:09 PM
skymuster (Mike)
Registered User

skymuster is offline
 
Join Date: Apr 2018
Location: Altona, VIC
Posts: 7
Hi Harrison,

I have an almost exact same setup to you (NEQ6 + SkyWatcher Black Diamond 250 / 1200) which I use successfully for DSO imaging. I use a modified Canon EOD500D as my main imaging camera. Here's a link to my instagram account with the photos I've achieved with this setup: www.instagram.com/newbym


For guiding I have the same planetary camera (ZWO ASI120MC) which I actually attached to the standard guidescope that came with the telescope, using a home-made adapter (i.e. a "finder-guider"). This is lighter than using a small refractor but seems to track ok. My average guiding error is typically around 1 arcsec which is fine for 3-4 min sub exposures. Anything longer than this and my subs tend to get washed out with the light pollution anyway.

The mount and guide cam are all controlled from the laptop using EQMOD and PHD2. Image capture and plate solving is done through Sequence Generator Pro.

I have been toying with the idea of an off-axis guider at some point in the future to further reduce strain on the mount and possibly get some more accurate tracking (assuming I can find suitable guide stars!).

Cheers,
Mike.
Reply With Quote
  #5  
Old 13-03-2019, 04:28 PM
hpgregory (Harrison)
Registered User

hpgregory is offline
 
Join Date: Mar 2019
Location: Launceston
Posts: 2
Thanks for the information guys! After looking at my equipment over the weekend and considering an OAG, it really seems that as is I only have about 1cm of backfocus left on my scope so I think a OAG is kinds out...

Mike your information and help is tremendous! Thank you so much! I'm so happy to find someone as successful as you with my setup, I was beginning to think I had the wrong setup for my purpose. Your instagram is very VERY amazing! Definitely got a new follower! I was wondering if the finder would be suitable so thank you for pointing that out. I will definitely take that into consideration!
Reply With Quote
  #6  
Old 14-03-2019, 10:03 PM
doppler's Avatar
doppler (Rick)
Registered User

doppler is offline
 
Join Date: Nov 2012
Location: Mackay
Posts: 1,603
Hi Harrison, I have a similar setup to you and Mike. 250mm f5 Skywatcher (but on an HEQ5 pro mount... overloaded on paper but not in practice). I originally started guiding with a finder guider but then went to the Orion thin oag. It took a bit of fiddling with thin spacers to get the guide camera to be at the same focus as the imaging camera, but after that its been plug and play. The thin oag is designed for DSLR's and has the same back space as a T mount.

Here's a pic of my 1100d, Orion thin oag, Baader coma corrector and ZWO 120mc guide cam.
Rick
Attached Thumbnails
Click for full-size image (orion oag.jpg)
161.9 KB25 views
Reply With Quote
  #7  
Old 20-03-2019, 09:58 PM
skymuster (Mike)
Registered User

skymuster is offline
 
Join Date: Apr 2018
Location: Altona, VIC
Posts: 7
Hi Rick,

I have literally just ordered the Orion thin OAG - it should be delivered next week!

My DSLR is virtually at the focus limit so I have been a bit concerned that it would add too much extra back focus spacing, however from your post (and photo) it looks like it will be fine - fingers crossed! I'll report back once I have put it all together.

Not having used an OAG before, do you find you have any issues in finding suitable guide stars?

Cheers,
Mike.
Reply With Quote
  #8  
Old 23-03-2019, 08:53 PM
doppler's Avatar
doppler (Rick)
Registered User

doppler is offline
 
Join Date: Nov 2012
Location: Mackay
Posts: 1,603
Hi Mike, finding guide stars can be a bit of a pain on some objects with the 120 colour, (the ASI 120 mono would be a lot better) sometimes I have to move the object off center to find a good guide star.
The hardest part in setting up the thin oag is getting the right spacers so that both cameras are at focus, but once that is done you don't have to worry about that again. With my DSLR (1100D crop sensor) I found it easier to move the oag prism right in and adjust the guide camera spacing for focus with a thin spacer. With my camera I only needed a 5mm spacer and the thin locking ring from the variable spacer in the kit to get the 120mc to the same focus as the 1100D.

https://www.bintel.com.au/product/bi...v=6cc98ba2045f


Rick

Last edited by doppler; 23-03-2019 at 11:58 PM.
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 02:12 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Limpet Controller
Advertisement
Testar
Advertisement
Bintel
Advertisement
Astronomy and Electronics Centre
Advertisement