EX1 visible chromatic aberrations on slashcam at DVinfo.net

Dieter Kollwitz · December 21st, 2007, 05:53 AM

There is a nice german article on slashcam.de about the chromatic aberrations of the EX1.

http://www.slashcam.de/artikel/Scoop...EX1-Optik.html

or (quite bad) translated.

http://www.google.com/translate?u=ht...&hl=en&ie=UTF8

My english is not as perfect as my german but here is a short summary: The Fujinon lens of the EX1 produces a lot of chromatic aberrations, but (!!) the Cam has a build in digital CAC (chromatic aberrations correction). But the CAC is only active when there is no lense movement like zoom. So you can see the aberrations clearly while you zoom.
The page has two nice 200% slpitscreens, where you can see the difference. Many people heard about the CAC before, but here you can see the difference. So maybe its important for someones buying decision...

Happy Christmas

Dieter

Thomas Smet · December 21st, 2007, 09:11 AM

This is nuts. Even SD cameras have this. Why even point it out anymore? They talk about how thsi is some type of defect but it is just something we have to live with. Now that so many people have high quality cameras every little imperfection they see gets blown out of the water and made into such a big deal.

Paul Curtis · December 21st, 2007, 09:14 AM

interesting discovery! on the example QT movie there is a real jump right at the end of zoom, is that just an operator thing or is that the CAC kicking in? Because if it's the CAC that's pretty distracting...

The aberation isn't too bad bearing in mind the scene and that they are pixel peeping...

cheers
paul

Steven Thomas · December 21st, 2007, 09:14 AM

I've seen lens that cost 3X the cost of the EX1 have CA. I agree, why bother.
Also, from what I see, regardless when it "may" occur, it's by far better than my previous cameras.

Steven Thomas · December 21st, 2007, 09:19 AM

On top of that...
I'm looking at some of my footage during zooms right now, and I'm not really seeing much... If it's there, it's not jumping out, so it's not a problem.

My JVC HD100 had FAR more CA.

Evan Donn · December 21st, 2007, 10:38 AM

I think I can live with it - zoom is nothing more than a way to reframe for me 95% of the time.

With my XH-A1 I recently shot an interview with someone in a black shirt against a white wall, sitting on one side of the frame...the thin pink line outlining one side of their shirt is pretty distracting - that's the kind of CA I'm concerned about, the kind that jumps out of a static shot where the viewer's eyes have a chance to focus on it - and it looks like that's exactly what the CA correction of the EX1 eliminates.

Greg Boston · December 22nd, 2007, 07:44 AM

CA is even more difficult to tame with HD lenses. I read this somewhere while researching the causes of CA in general.

The biggest offender is running wide open on the long end of the lens.

-gb-

Bill Ravens · December 22nd, 2007, 08:15 AM

So, exactly what is it that causes the CA. One arguement is that it's caused by optical distortion of the different wavelengths of light thru the lens. A high quality $1500 still camera lens corrects out CA. Another arguement is that it's related to using 3 sensors. Which one is it?

Greg Boston · December 22nd, 2007, 09:07 AM

Quote:

Originally Posted by Bill Ravens

So, exactly what is it that causes the CA. One arguement is that it's caused by optical distortion of the different wavelengths of light thru the lens. A high quality $1500 still camera lens corrects out CA. Another arguement is that it's related to using 3 sensors. Which one is it?

All of the above. It's virtually impossible to get a lens to pass all wavelengths equally in all situations and the three chip design with prism block will definitely exploit any weakness in the lens's ability. The video lens is more complex because it has to minimize breathing which introduces more moving elements to compensate.

I'll see if I can dig up the links to the pages I was reading.

-gb-

Bill Ravens · December 22nd, 2007, 09:21 AM

Greg..

So, what you're saying is that it's easier for a 35mm lens to correct out CA because it doesn't have optical elements that correct breathing? I have some very nice Canon EOS zooms that don't show a hint of CA at any zoom or aperture setting. These zooms are very complex designs.

Chris Hurd · December 22nd, 2007, 09:21 AM

Quote:

Originally Posted by Bill Ravens

A high quality $1500 still camera lens corrects out CA.

A large zoom ratio really brings out CA, and a high quality $1500 still camera lens does not have a large zoom ratio. Even the longest telephoto zooms in still photography are typically only 3x or 4x. However in video it's common to have 14x to 20x zoom lenses, and that's why CA is much more apparent in video than in still photography. The shorter the zoom ratio (not the focal length but the zoom ratio) the easier it is to correct, and the less likely a lens will exhibit CA.

Required reading: "HDTV Lens Design: Management of Chromatic Aberrations"
http://www.usa.canon.com/industrial_...WhitePaper.pdf

Bill Ravens · December 22nd, 2007, 09:37 AM

Thanx, everyone.

Greg Boston · December 22nd, 2007, 09:40 AM

Quote:

Originally Posted by Bill Ravens

Thanx, everyone.

Here is one link that describes the scenario, including what Chris alluded to.

http://www.canon.com/bctv/faq/chrab.html

This not the the page I was recalling... still looking for that one.

Bill Ravens · December 22nd, 2007, 10:35 AM

Thanx, Greg. I already knew what causes CA in lenses. I didn't understand why videocam lenses had so much more CA than 35mm cam lenses. I think you and Chris gave me the answer. Videocam lenses have much harder optical problems to neutralize, namely long zoom ratios and mitigation of breathing effects.

Actually, it makes a good case for having an interchangeable lens camera and small zoom ratio lenses.

Greg Boston · December 22nd, 2007, 10:43 AM

Quote:

Originally Posted by Bill Ravens

Thanx, Greg. I already knew what causes CA in lenses. I didn't understand why videocam lenses had so much more CA than 35mm cam lenses. I think you and Chris gave me the answer. Videocam lenses have much harder optical problems to neutralize, namely long zoom ratios and mitigation of breathing effects.

Actually, it makes a good case for having an interchangeable lens camera and small zoom ratio lenses.

Yep, or at least a lens with a built in 2X for those times when you need the extra reach. Wishing I had the 13x3.3 with 2X on my XDCAM HD.

-gb-

December 21st, 2007, 05:53 AM	#1
Dieter Kollwitz Tourist Join Date: Dec 2006 Location: Berlin Germany Posts: 1	EX1 visible chromatic aberrations on slashcam There is a nice german article on slashcam.de about the chromatic aberrations of the EX1. http://www.slashcam.de/artikel/Scoop...EX1-Optik.html or (quite bad) translated. http://www.google.com/translate?u=ht...&hl=en&ie=UTF8 My english is not as perfect as my german but here is a short summary: The Fujinon lens of the EX1 produces a lot of chromatic aberrations, but (!!) the Cam has a build in digital CAC (chromatic aberrations correction). But the CAC is only active when there is no lense movement like zoom. So you can see the aberrations clearly while you zoom. The page has two nice 200% slpitscreens, where you can see the difference. Many people heard about the CAC before, but here you can see the difference. So maybe its important for someones buying decision... Happy Christmas Dieter

December 21st, 2007, 10:38 AM	#6
Evan Donn Major Player Join Date: Feb 2006 Location: Philadelphia Posts: 795	I think I can live with it - zoom is nothing more than a way to reframe for me 95% of the time. With my XH-A1 I recently shot an interview with someone in a black shirt against a white wall, sitting on one side of the frame...the thin pink line outlining one side of their shirt is pretty distracting - that's the kind of CA I'm concerned about, the kind that jumps out of a static shot where the viewer's eyes have a chance to focus on it - and it looks like that's exactly what the CA correction of the EX1 eliminates. __________________ My latest short documentary: "Four Pauls: Bring the Hat Back!"

December 21st, 2007, 09:11 AM	#2
Thomas Smet Trustee Join Date: Mar 2004 Location: Milwaukee, WI Posts: 1,719	This is nuts. Even SD cameras have this. Why even point it out anymore? They talk about how thsi is some type of defect but it is just something we have to live with. Now that so many people have high quality cameras every little imperfection they see gets blown out of the water and made into such a big deal.

December 21st, 2007, 09:14 AM	#3
Paul Curtis Major Player Join Date: Mar 2005 Location: canterbury Posts: 411	interesting discovery! on the example QT movie there is a real jump right at the end of zoom, is that just an operator thing or is that the CAC kicking in? Because if it's the CAC that's pretty distracting... The aberation isn't too bad bearing in mind the scene and that they are pixel peeping... cheers paul

December 21st, 2007, 09:14 AM	#4
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	I've seen lens that cost 3X the cost of the EX1 have CA. I agree, why bother. Also, from what I see, regardless when it "may" occur, it's by far better than my previous cameras.

December 21st, 2007, 09:19 AM	#5
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	On top of that... I'm looking at some of my footage during zooms right now, and I'm not really seeing much... If it's there, it's not jumping out, so it's not a problem. My JVC HD100 had FAR more CA.

December 22nd, 2007, 07:44 AM	#7
Greg Boston Wrangler Join Date: Oct 2003 Location: DFW area, TX Posts: 6,117 Images: 1	CA is even more difficult to tame with HD lenses. I read this somewhere while researching the causes of CA in general. The biggest offender is running wide open on the long end of the lens. -gb-

December 22nd, 2007, 08:15 AM	#8
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	So, exactly what is it that causes the CA. One arguement is that it's caused by optical distortion of the different wavelengths of light thru the lens. A high quality $1500 still camera lens corrects out CA. Another arguement is that it's related to using 3 sensors. Which one is it?

December 22nd, 2007, 09:21 AM	#10
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Greg.. So, what you're saying is that it's easier for a 35mm lens to correct out CA because it doesn't have optical elements that correct breathing? I have some very nice Canon EOS zooms that don't show a hint of CA at any zoom or aperture setting. These zooms are very complex designs.

December 22nd, 2007, 09:37 AM	#12
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Thanx, everyone.

December 22nd, 2007, 10:35 AM	#14
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Thanx, Greg. I already knew what causes CA in lenses. I didn't understand why videocam lenses had so much more CA than 35mm cam lenses. I think you and Chris gave me the answer. Videocam lenses have much harder optical problems to neutralize, namely long zoom ratios and mitigation of breathing effects. Actually, it makes a good case for having an interchangeable lens camera and small zoom ratio lenses.