#1  
Old 05-12-2020, 07:30 PM
Loupy31's Avatar
Loupy31 (Peter)
Invented the Four Track

Loupy31 is offline
 
Join Date: Jun 2005
Location: Clayton SA
Posts: 311
Focal reducer

Hi Guys

Ok, I have an ASI294 mc pro, its attached to An Orion ED 80,
If I place a .85 reducer into the optical path, will the focus distance be closer to the scope ?

Peter
Reply With Quote
  #2  
Old 05-12-2020, 09:03 PM
Joshua Bunn's Avatar
Joshua Bunn (Joshua)
Registered User

Joshua Bunn is offline
 
Join Date: Oct 2011
Location: Albany, Western Australia
Posts: 1,271
Yes, it will focus closer to the telescope, a Barlow (focal extender) will push the focus away from the telescope.


Josh
Reply With Quote
  #3  
Old 05-12-2020, 09:10 PM
Zuts
Registered User

Zuts is offline
 
Join Date: Mar 2007
Location: sydney
Posts: 1,735
Hi,

I have a TV85 with a FL of 600mm. I use a 0.8 reducer which gives me a 480mm FL.


Bearing in mind ZWO cameras require a 55 mm backfocus I have spacers screwed into the camera so that there is 55 mm between the top of the reducer to the chip.

When I measure with a tape there is 480 mm from the front lens of the scope to the lens of the reducer when everything is in focus.

You have an ED80 which has the same FL, but a 0.85 reducer. So I would do roughly the same to get a rough focus, i.e camera with 55 mm of spacing to the chip, then reducer, then roughly 510mm to front of telescope lens and you should see stars when you take a photo. Then you need to fine focus from there.

Last edited by Zuts; 06-12-2020 at 02:00 AM.
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 07:35 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Bintel
Advertisement
Testar
Advertisement
Limpet Controller
Advertisement
Astronomy and Electronics Centre
Advertisement