Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Flattener Reducer needed for long focal length refractor?

astrophotography dslr equipment imaging optics refractor
  • Please log in to reply
2 replies to this topic

#1 ericthemantis

ericthemantis

    Ranger 4

  • *****
  • topic starter
  • Posts: 324
  • Joined: 09 May 2016
  • Loc: Phoenix, AZ

Posted 08 August 2020 - 11:13 PM

Astronomics finally had AT60FF in stock a few months ago and the difference in the sharpness of my imaging from my AT60ED is mind blowing. I've got a Celestron C102-HD that I use for planetary imaging and occasional deep-sky imaging. I know being an f/10 the need for a field flattener is not as important, but I am curious if it would improve my images to get a flattener or flattener/reducer for it. Whether that is getting slightly sharper details on some planets, or getting a sharper star-field around a globular star cluster.

 

If it would help, where would I get one that would work for an f/10 1000mm FL achromatic? I see ones for SCT's, would those work? I don't see a lot about flatteners or reducers for slow refractors.

 

I image with a Canon T5i - an APS-C crop sensor. I do deep-sky imaging with the full sensor, but planetary is with BYEOS using the 5x zoom live view feed so just a small rectangle in the center of the sensor.



#2 ericthemantis

ericthemantis

    Ranger 4

  • *****
  • topic starter
  • Posts: 324
  • Joined: 09 May 2016
  • Loc: Phoenix, AZ

Posted 10 August 2020 - 10:12 AM

Maybe the wrong forum group?

 

F/10 1000mm long refractor. Will a field flattener/reducer improve sharpness at the edge of my images? If yes, how do I choose one, since most if not all at that focal ratio are labeled for SCT's.

 

I'll go try and dig up a picture taken with this scope for reference.



#3 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 21,113
  • Joined: 27 Oct 2014

Posted 10 August 2020 - 10:40 AM

Perhaps I can shed a modest amount of light on the issue.

 

The long focal length scope has less field curvature.  Whether or not a field flattener would make a significant improvement is an open question.

 

Almost no one uses that scope for DSO photography (old long slow doublet with chromatic aberration), so there's no market for a flattener.

 

The completely different optical characteristics of an F10 SCT make it _very_ unlikely a flattener/reducer designed for an SCT would work.  Even among different refractors, flattener/reducers are not universal, the one designed for the specific scope is generally the way to go.


Edited by bobzeq25, 10 August 2020 - 10:46 AM.

  • Pat Brubeck and ericthemantis like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: astrophotography, dslr, equipment, imaging, optics, refractor



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics