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

Reply
 
Thread Tools Rate Thread
  #1  
Old 14-01-2011, 02:12 PM
mswhin63's Avatar
mswhin63 (Malcolm)
Registered User

mswhin63 is offline
 
Join Date: May 2009
Location: Bertram, Western Australia
Posts: 3,327
Any suggestion on Fringe filters for camera lens

Hi

Pictured in the osot - http://www.iceinspace.com.au/forum/s...ad.php?t=70588, I have a fringe issue and would like to know what is the best filter for the job. When I bought the lens it had a UV filter although was a cheapy used for protecting the lens glass but it caused some ghosting. So the original image looked like loads of elongated binary stars.

I am sure there is a fair amount of glass reflection with the filter in place.

Really would like a suggestion before spending too much on trial and error.

The lens is a Canon EF 75-300mm affordable for me, can't spend loads on high end lens at the moment. Attached is an mostly unprocessed M45.
Attached Thumbnails
Click for full-size image (Ple_Dss.jpg)
146.4 KB20 views
Reply With Quote
  #2  
Old 14-01-2011, 04:52 PM
Octane's Avatar
Octane (Humayun)
IIS Member #671

Octane is offline
 
Join Date: Dec 2005
Location: Canberra
Posts: 11,158
That lens is notorious for chromatic aberration.

You're going to have a very hard time removing that no matter what filter you use.

H
Reply With Quote
  #3  
Old 14-01-2011, 05:00 PM
dugnsuz's Avatar
dugnsuz (Doug)
to baldly go...

dugnsuz is offline
 
Join Date: Aug 2005
Location: Hahndorf, South Australia
Posts: 4,200
Malcom - Don't waste money on a filter for your particular lens as H says.

If you're using Photoshop to process your images, there is a couple of CA removal/reduction tools in Noel Carboni's PS actions...
http://www.prodigitalsoftware.com/As...l_Version.html

Way cheaper ($21.95US) than a filter and you'll have fun with the other actions too!
Found specific one...
http://www.prodigitalsoftware.com/im..._Reduction.jpg
Cheers
Doug
Reply With Quote
  #4  
Old 14-01-2011, 05:09 PM
mswhin63's Avatar
mswhin63 (Malcolm)
Registered User

mswhin63 is offline
 
Join Date: May 2009
Location: Bertram, Western Australia
Posts: 3,327
I dont have PS (expensive), but am hopefully going to school again soon so may get an education version. I may still get a UV multicoated lense anyway at least to reduce the effects but I also may get some RGB filters and work on refocusing on all the colours.

I do have a PS plugin for GIMP, but I am not sure prodigital software will work with all the PS plugins, I know some plug-ins work. Too bad can't try it or verify it works before purchasing it.

Thanks for the advice.
Reply With Quote
  #5  
Old 14-01-2011, 10:27 PM
irwjager's Avatar
irwjager (Ivo)
Registered User

irwjager is offline
 
Join Date: Apr 2010
Location: Melbourne
Posts: 492
You could manually perform defringing in, for example, the GIMP. It may be a bit laborious, but the result is pretty decent.

* Create a mask (or selection) that includes the stars that suffer from the fringe/halos (including the purple fringe/halos themselves).
* Reject the purple color (only operating on the selected stars). It's ok if the pixels you modified are now darker than the background.
* Put this result aside.

* Now start off again with the original in a separate image (or layer).
* Use the same star mask (you may have to grow it a bit) and heal (or otherwise make disappear) the stars, including fringes/halo. The smoother the better - it should appear as if the stars were never there.

* Now layer the starless image on top of the first image (with the purple color rejected) and set the blend mode to lighten.

You should now have a fringeless and halo free image.

I attached an example I created with StarTools (see here for original).
Attached Thumbnails
Click for full-size image (fringe_defringed.jpg)
195.1 KB10 views
Click for full-size image (fringe2_defringed.jpg)
184.1 KB14 views

Last edited by irwjager; 14-01-2011 at 10:47 PM.
Reply With Quote
  #6  
Old 15-01-2011, 02:12 AM
mswhin63's Avatar
mswhin63 (Malcolm)
Registered User

mswhin63 is offline
 
Join Date: May 2009
Location: Bertram, Western Australia
Posts: 3,327
Nice advise, that is a lot to work with thanks.
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 12:13 PM.

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