#1  
Old 08-01-2020, 11:12 AM
Granada
The truth is out there

Granada is offline
 
Join Date: Feb 2016
Location: Melbourne
Posts: 130
120 ED and reducer threads

Hi, I'm confused about what adapters/rings/etc to look for to link my Skywatcher 120 ED with a focal reducer and a Canon DSLR. I've attached a few photos to show what I've already got in hope someone can tell me what I'm missing.


Starting with the first photo containing the entire setup, from left to right is the OTA (http://www.skywatcher.com/product/bk-120ed-otaw/), followed by the focal reducer (http://www.skywatcher.com/product/focal-reducer-120ed/), followed by Bintel's 2" camera adapter and lastly Bintel's Canon EOS T-ring. I assume I don't need the camera adapter, but a M48-M42 step down ring, correct? That just leaves me with something to couple the OTA with the reducer...



Many thanks
Attached Thumbnails
Click for full-size image (IMG_1979.jpg)
106.5 KB29 views
Click for full-size image (IMG_1980.jpg)
120.5 KB24 views
Click for full-size image (IMG_1982.jpg)
143.7 KB24 views
Click for full-size image (IMG_1983.jpg)
151.6 KB22 views
Click for full-size image (IMG_1984.jpg)
136.9 KB16 views
Reply With Quote
  #2  
Old 08-01-2020, 11:31 AM
Granada
The truth is out there

Granada is offline
 
Join Date: Feb 2016
Location: Melbourne
Posts: 130
By the way, I've just realised that if I spin the reducer the other way around, so that the male part is facing the camera adapter, and the female part is facing the OTA, I can get the 2" adapter to work just fine without any step down rings.
Reply With Quote
  #3  
Old 08-01-2020, 11:32 AM
brisen (Brian)
Registered User

brisen is offline
 
Join Date: Aug 2013
Location: Caboolture, Australia
Posts: 256
You should be able to unscrew the end off the focuser tube - the bit with the thumbscrews unscrews and should be the same thread as the reducer which will screw on. Turn it around to the opposite of how you have it in the photo. Does the 2" to T2 then screw onto the end of the reducer? If not you will need to get the step down from the reducer to the 2" to T2. I have an ED 120 but not with the reducer - so cant check the size. I assume also that you will need to get the spacing correct for the back focus distance which for Canon is 55mm to the sensor.

Brian
Reply With Quote
  #4  
Old 08-01-2020, 11:51 AM
Granada
The truth is out there

Granada is offline
 
Join Date: Feb 2016
Location: Melbourne
Posts: 130
Quote:
Originally Posted by brisen View Post
You should be able to unscrew the end off the focuser tube - the bit with the thumbscrews unscrews and should be the same thread as the reducer which will screw on. Turn it around to the opposite of how you have it in the photo.

That seems to have done the trick. I didn't even think about unscrewing the end of the focuser tube


Quote:
Originally Posted by brisen View Post
Does the 2" to T2 then screw onto the end of the reducer?

Yep, it does


Quote:
Originally Posted by brisen View Post
I assume also that you will need to get the spacing correct for the back focus distance which for Canon is 55mm to the sensor.

Yeah that's why I wasn't sure if the camera adapter is adequate for this purpose. Might need to do some experimenting...
Reply With Quote
  #5  
Old 08-01-2020, 03:40 PM
Outcast's Avatar
Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
 
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,054
Quote:
Originally Posted by Granada View Post
Yeah that's why I wasn't sure if the camera adapter is adequate for this purpose. Might need to do some experimenting...
If you are shooting with a Canon, your T2 adaptor screwed directly to the flattener should get you exceptionally close to the 55mm sensor spacing...

Might just need a slight tweak here or there to get it spot on...
Reply With Quote
  #6  
Old 08-01-2020, 03:44 PM
Granada
The truth is out there

Granada is offline
 
Join Date: Feb 2016
Location: Melbourne
Posts: 130
Quote:
Originally Posted by Outcast View Post
If you are shooting with a Canon, your T2 adaptor screwed directly to the flattener should get you exceptionally close to the 55mm sensor spacing...

Might just need a slight tweak here or there to get it spot on...

Yep that's what I'm planning to do: OTA -> focuser -> T2 adapter -> EOS T-ring -> DSLR
Reply With Quote
  #7  
Old 08-01-2020, 08:32 PM
Outcast's Avatar
Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
 
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,054
Quote:
Originally Posted by Granada View Post
Yep that's what I'm planning to do: OTA -> focuser -> T2 adapter -> EOS T-ring -> DSLR
Sorry, I misspoke.. t ring should get you pretty close on its own... from memory, sensor depth on a Canon with nothing fitted is around 52mm..
Reply With Quote
  #8  
Old 08-01-2020, 08:39 PM
Outcast's Avatar
Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
 
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,054
Bugger...

I have t adapter on the brain.. I meant T ring.. I've edited the previous post...

For example: I only use a t-adapter of 50mm when I am using a focal reducer & require 105mm of back focus... If using my flattener or coma corrector (dependant on scope being used) I only connect to my T-ring (m42 thread)... that's for my Canon 70d..

If I use my ZWO I need to factor in an additional 43mm as the sensor depth on that camera is only 12mm.. hope that makes more sense...
Reply With Quote
  #9  
Old 08-01-2020, 08:51 PM
Granada
The truth is out there

Granada is offline
 
Join Date: Feb 2016
Location: Melbourne
Posts: 130
Oh ok I see. My t-ring isn't compatible with the focuser, so I'll probably need to buy a M48-M42 step down ring then. Hopefully that'll be just about right in terms of focus
Reply With Quote
  #10  
Old 08-01-2020, 10:18 PM
Outcast's Avatar
Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
 
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,054
Quote:
Originally Posted by Granada View Post
Oh ok I see. My t-ring isn't compatible with the focuser, so I'll probably need to buy a M48-M42 step down ring then. Hopefully that'll be just about right in terms of focus
You can, I believe, get a t ring that has an m48 thread... but, yes, a step down ring may work..
Reply With Quote
  #11  
Old 27-01-2020, 04:39 PM
kon1966 (Kon)
Registered User

kon1966 is offline
 
Join Date: Apr 2008
Location: Villawood
Posts: 224
Custom adapter

Hi,
Had a custom adapter made by Josh for my ed80. I wanted a 2 inch adapter where I could screw a filter on permanently then screw on a celestron f6.3 reducer and then screw on my canon eos. Look at my link below for pics and the thread and hope ithelps

http://www.iceinspace.com.au/forum/a...hmentid=249061

Regards
Kon
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 11:53 PM.

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