Chromatic aberration at DVinfo.net

Mark David Williams · April 18th, 2008, 07:35 AM

Does anyone know how to get rid of it? Im using an iscorama 54 anamorphic adapter on an EX-1 and noticing a degree of colour fringing sometimes that just doesn't happen on the EX-1s amazing lens. Just wondered if anyone knew of a program to get rid of this?

Tom Hardwick · April 18th, 2008, 08:16 AM

Iscorama 54 huh? So you're shooting 2.66:1 movies. Great! The punch of that is probably worth having some fringing on board.

Mark David Williams · April 18th, 2008, 08:49 AM

Agree Tom!

Paul Curtis · April 18th, 2008, 10:03 AM

Mark,

It depends on the type of aberration. You might be able to run the footage through after effects and scale the RGB channels differently if it's a simple type of fringing. Other things you can do is to key the fringe colours and desaturate them, sometimes this can work, it really depends on the type of footage.

I'd love to see a frame. What's the resolution like through that adaptor?

cheers
paul

Mark David Williams · April 18th, 2008, 11:16 AM

Hi Paul

This is without the anamorph

http://www.freewebs.com/markwilliams/without.png

And this is with

http://www.freewebs.com/markwilliams/Anamorph.png

Tom Hardwick · April 18th, 2008, 11:21 AM

Oh dear - I see what you mean. Almost better to mask down the original frame rather than have to accept wooshy edges like that.

Paul Curtis · April 18th, 2008, 11:40 AM

I was about to say something similar. i thought the lens would give you a much wider fov. In this case you'd get better results cropping the original down as Tom says.

Is the adaptor meant for 4:3 cameras perhaps?

Having said that you could squeeze the channels horizontally (try expanding the red a little bit widthwise, 100.25%), i think it would clear it up a bit. Or run it through a photographic (RAW converter) style defringer.

cheers
paul

Bill Ravens · April 18th, 2008, 11:57 AM

VirtualDub has a free CA correction filter. Do a search.

Mark David Williams · April 18th, 2008, 12:01 PM

Quote:

Originally Posted by Bill Ravens

VirtualDub has a free CA correction filter. Do a search.

Bill I was just thinking about you! I was using your picture profile when I took it. This is with Picture profiles off

http://www.freewebs.com/markwilliams...20pp%20off.png

Mika Tertsunen · April 18th, 2008, 01:30 PM

Err, having looked at the pictures; don´t really know which way to take this. Better without?

Mark David Williams · April 18th, 2008, 01:42 PM

Mika I would say no difference with PP on or off. I just thought people might like to see nd judge for themselvves. Bill I've found the plugin and downloaded virtual dub. Imported the picture and added the filter. However I cant see the effect in the preview screen? When I do get a preview screen its zoomed in so much cant see a lot?

Mark David Williams · April 18th, 2008, 01:57 PM

I would guess though whatever I do Im not going to get rid of this! Im surprised virtual dub has a tool like this and after effects doesn't.

Mark David Williams · April 18th, 2008, 02:31 PM

I wonder if I moved the iscorama forward a bit? I'll try that tommorow.

Mika Tertsunen · April 18th, 2008, 03:23 PM

I guess you could get away with it quite simply by forgetting about the anamorphic adaptor, having framing guidelines in your monitor/viewfinder and cropping afterwards. I don´t know if it´s possible to define a box cursor to the ex, hardly so.

Bill Ravens · April 19th, 2008, 07:08 AM

The PP settings won't be the cause of CA.(doncha just love acronyms?)
But, my question to you is what aperture settings did you use on the shot with and without CA. CA, in hi quality optics, is made worse by long zooms and apertures too far from the sweet spot. If you were shooting down around f/8 or less, this would be my guess. Also, how does the adapter mount to the cam lens? If it's tilted, even slightly, relative to the lens axis, you could induce CA.

April 18th, 2008, 07:35 AM	#1
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	Chromatic aberration Does anyone know how to get rid of it? Im using an iscorama 54 anamorphic adapter on an EX-1 and noticing a degree of colour fringing sometimes that just doesn't happen on the EX-1s amazing lens. Just wondered if anyone knew of a program to get rid of this?

April 18th, 2008, 08:16 AM	#2
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Iscorama 54 huh? So you're shooting 2.66:1 movies. Great! The punch of that is probably worth having some fringing on board.

April 18th, 2008, 08:49 AM	#3
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	Agree Tom!

April 18th, 2008, 10:03 AM	#4
Paul Curtis Major Player Join Date: Mar 2005 Location: canterbury Posts: 411	Mark, It depends on the type of aberration. You might be able to run the footage through after effects and scale the RGB channels differently if it's a simple type of fringing. Other things you can do is to key the fringe colours and desaturate them, sometimes this can work, it really depends on the type of footage. I'd love to see a frame. What's the resolution like through that adaptor? cheers paul

April 18th, 2008, 11:16 AM	#5
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	Hi Paul This is without the anamorph http://www.freewebs.com/markwilliams/without.png And this is with http://www.freewebs.com/markwilliams/Anamorph.png

April 18th, 2008, 11:21 AM	#6
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Oh dear - I see what you mean. Almost better to mask down the original frame rather than have to accept wooshy edges like that.

April 18th, 2008, 11:40 AM	#7
Paul Curtis Major Player Join Date: Mar 2005 Location: canterbury Posts: 411	I was about to say something similar. i thought the lens would give you a much wider fov. In this case you'd get better results cropping the original down as Tom says. Is the adaptor meant for 4:3 cameras perhaps? Having said that you could squeeze the channels horizontally (try expanding the red a little bit widthwise, 100.25%), i think it would clear it up a bit. Or run it through a photographic (RAW converter) style defringer. cheers paul

April 18th, 2008, 11:57 AM	#8
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	VirtualDub has a free CA correction filter. Do a search.

April 18th, 2008, 01:30 PM	#10
Mika Tertsunen Regular Crew Join Date: Feb 2008 Location: Finland Posts: 25	Err, having looked at the pictures; don´t really know which way to take this. Better without?

April 18th, 2008, 01:42 PM	#11
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	Mika I would say no difference with PP on or off. I just thought people might like to see nd judge for themselvves. Bill I've found the plugin and downloaded virtual dub. Imported the picture and added the filter. However I cant see the effect in the preview screen? When I do get a preview screen its zoomed in so much cant see a lot?

April 18th, 2008, 01:57 PM	#12
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	I would guess though whatever I do Im not going to get rid of this! Im surprised virtual dub has a tool like this and after effects doesn't.

April 18th, 2008, 02:31 PM	#13
Mark David Williams Major Player Join Date: Dec 2007 Location: Hertfordshire UK Posts: 414	I wonder if I moved the iscorama forward a bit? I'll try that tommorow.

April 18th, 2008, 03:23 PM	#14
Mika Tertsunen Regular Crew Join Date: Feb 2008 Location: Finland Posts: 25	I guess you could get away with it quite simply by forgetting about the anamorphic adaptor, having framing guidelines in your monitor/viewfinder and cropping afterwards. I don´t know if it´s possible to define a box cursor to the ex, hardly so.

April 19th, 2008, 07:08 AM	#15
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	The PP settings won't be the cause of CA.(doncha just love acronyms?) But, my question to you is what aperture settings did you use on the shot with and without CA. CA, in hi quality optics, is made worse by long zooms and apertures too far from the sweet spot. If you were shooting down around f/8 or less, this would be my guess. Also, how does the adapter mount to the cam lens? If it's tilted, even slightly, relative to the lens axis, you could induce CA.