Chromatic aberration and back focus at DVinfo.net

Go Back   DV Info Net > Special Interest Areas > Alternative Imaging Methods

Alternative Imaging Methods
DV Info Net is the birthplace of all 35mm adapters.


Reply
 
Thread Tools Search this Thread
Old February 26th, 2008, 03:16 AM   #1
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Chromatic aberration and back focus

I had changed the back focus on my camera to fit a minolta zoom lens on it, so that it could zoom without losing focus.

But as I now have a proper C-mount machine-vision prime lens maybe the back focus needs to be redone. Can the chromatic aberrations be caused by having the back focus set incorrectly?
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old February 26th, 2008, 10:03 AM   #2
Obstreperous Rex
 
Join Date: Jan 2001
Location: San Marcos, TX
Posts: 26,900
Images: 513
Quote:
Originally Posted by Take Vos View Post
Can the chromatic aberrations be caused by having the back focus set incorrectly?
Most certainly yes they can.

From HDTV Lens Design: Management of Chromatic Aberrations, by Larry Thorpe and Gordon Tubbs:

"...it was fully recognized by all of the camera and lens manufacturers that chromatic aberrations were a regrettable impairment that could never be totally eliminated. The camera manufacturers and optical manufacturers worked within the Broadcast Technology Association (BTA) in the late 1980s to address all aspects of the 2/3in HDTV camera and lens interface.... The studies included grappling with the issue of longitudinal and lateral chromatic aberration and its variances with focal length. A key element within this standard was the agreement on a precision Flange Back dimension..."

At http://www.usa.canon.com/industrial_...WhitePaper.pdf
__________________
CH

Search DV Info Net | DV Info Net Sponsors | A Decade (+5) of DVi | ...Tuesday is Soylent Green Day!
Chris Hurd is offline   Reply With Quote
Old February 26th, 2008, 10:53 AM   #3
Major Player
 
Join Date: Mar 2007
Location: Amsterdam The Netherlands
Posts: 200
Chris,

I am not entirely convinced by this article, as it is about zoom lenses, not primes. I will play with the backfocus to see if I can reduce the aberrations.

Of course my development version of Boom Recorder is completely trashed right now, so it will take some time before I can do this test.

Cheers,
Take
__________________
VOSGAMES, http://www.vosgames.nl/
developer of Boom Recorder and Mirage Recorder
Take Vos is offline   Reply With Quote
Old February 26th, 2008, 11:58 AM   #4
Obstreperous Rex
 
Join Date: Jan 2001
Location: San Marcos, TX
Posts: 26,900
Images: 513
Sorry, yes, that entire series of white papers involves HDTV zoom lenses.
__________________
CH

Search DV Info Net | DV Info Net Sponsors | A Decade (+5) of DVi | ...Tuesday is Soylent Green Day!
Chris Hurd is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Special Interest Areas > Alternative Imaging Methods

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 05:02 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network