chromatic aberration on a new EX3

[Oliver Neubert]

Hi everyone,

I am experiencing severe chromatic aberration on my new EX3, especially when zoomed in fully. I am not sure if this is normal - kind of feel that it is more that acceptable.

It is most visble in high contrast areas, i.e. a patch of snow on a dark roof. Posted a framegrab here: http://abaku.net/test/Chromatic_Aber...EX3_Test_1.jpg

Does anyone have any information about this?

regards

Oliver

[Steve Phillipps]

Welcome to HD, it's pretty much universal even on a £35,000 Canon HJ40! I suppose there could be some sample variation and you could have a particularly bad one.
Steve

[Brian Luce]

Originally Posted by Oliver Neubert

Hi everyone,

I am experiencing severe chromatic aberration on my new EX3, especially when zoomed in fully. I am not sure if this is normal - kind of feel that it is more that acceptable.

It is most visble in high contrast areas, i.e. a patch of snow on a dark roof. Posted a framegrab here: http://abaku.net/test/Chromatic_Aber...EX3_Test_1.jpg

Does anyone have any information about this?

regards

Oliver

If you're coming from JVC PROHD this amount is a godsend. Those are severe conditions.

[Alister Chapman]

What F stop were you at. That image looks kind of soft, as though you are wide open in which case you will get some bad aberrations. Try to stay between F8 and F4

[Kevin Cates]

I just experienced something similar. I was shooting scenics and most all footage was OK except for one where I was 90 degrees from sun, fully zoomed in, at @ 4F stop.

Notice the red line on horizon and telephone poll.

I just sold my Canon XL-H1 and never had this issue. Is this normal for EX1? What is the fix?

[Steve Phillipps]

Originally Posted by Alister Chapman

What F stop were you at. That image looks kind of soft, as though you are wide open in which case you will get some bad aberrations. Try to stay between F8 and F4

Alister you probably know more about optical science than me, but I'm sure a paper I read on CA said that aperture value should have no effect on Translateral CA (ie colour fringing).

I looked at the still now, and to me I must say it looks pretty much par for the course with HD lenses, that's more or less what I've seen on lenses ranging from £5000 to £35000! Though some are less bad than others.
Steve

[Oliver Neubert]

Originally Posted by Alister Chapman

What F stop were you at. That image looks kind of soft, as though you are wide open in which case you will get some bad aberrations. Try to stay between F8 and F4

I know I did not shoot wide open, I believe I must have been between 4 and 5.6.
I had the problem with a 730 HDCAM with an non HD lens but then it was most apparent when shooting wide with a focal length of 4.5. I was not terribly surprised then, but zoomed in, using only the center part of the lens I did not expect this problem, at least not this much.


Is there any adjustments I can make to avoid or reduce this flaw?

[Oliver Neubert]

Originally Posted by Kevin Cates

I just experienced something similar. I was shooting scenics and most all footage was OK except for one where I was 90 degrees from sun, fully zoomed in, at @ 4F stop.

Notice the red line on horizon and telephone poll.

I just sold my Canon XL-H1 and never had this issue. Is this normal for EX1? What is the fix?

Kevin, I think it is exactly the same issue, if you look closely there is a cyan line at the opposite side of the red or magenta one on both telephone poles far left and right.

I wonder if there is a usable filter that will reduce this problem?

[Steve Phillipps]

Don't think a filter will help but you can get rid of it pretty well in post. Just pick that colour and de-saturate it (or something like that, I know I've seen my editors do it!)
Steve

[Alister Chapman]

Steve: While CA in itself is constant whatever the aperture if the lens is wide open or stopped down too far the overall image gets softer or slightly blurred, including the CA which makes the CA spread more. Image a completely sharp in focus line that is 2 pixels wide, well if it is soft or out of focus it may be 4 pixels wide, the same happens to the CA, so CA can become more apparent. CA is also dependent on the focal length of a zoom lens. Filters can make the situation worse as they add a further uncorrected (for CA) glass element.

[Leonard Levy]

I have the same experience zoomed in all the way on my Ex-1 on high contrast edges. Looked pretty bad to me so i try to avoid it. I've been told that you get it on many cameras, but i never noticed it as badly. I think its just part of the package for that price.

Lenny

[Steve Phillipps]

Leonard, as I said, I've seen it pretty bad on a £35,000 Canon HJ40, and have seen it on just about every single HD lens I've looked at, so it's not just because the EX lens is "budget" priced. It seems it's an HD disease.
I've never tried the likes of Cooke S4s, or Zeiss primes etc., I wonder if they're totally free of it?
Steve

[Greg Boston]

Yes, that's fairly common. A couple things I learned when I was first confronted by the CA problem.

Avoid going wide open at full telephoto.

As was mentioned, try to stay between F4 and F8.

High contrast areas outdoors with the sun high in the sky will often give a blue line to the right side of the object.

I found a site that discussed HD lens design. One of the key points I took away from that article was that the higher a lens' resolving power, the more difficult it is to tame CA.

CA is also more difficult to manage on a 3 chip design due to the prism block involved.

-gb-

[Tom Roper]

Originally Posted by Greg Boston

Avoid going wide open at full telephoto.

-gb-

It seems to me one more variable should be added into that mix, focal distance. If I zoom wide open at full telephoto to a subject 8 feet away, no problem with CA, but if I do the same on a distant landscape, fringing becomes more obvious.