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12/04/2010 03:36:24 AM · #1 |
I'm totally loving my new lens, but oh damn! can this thing produce some serious CA in certain situations..
Here's about the worst fringing I can imagine. This is a 1:1 crop..
Message edited by author 2010-12-04 03:36:36. |
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12/04/2010 07:11:04 AM · #2 |
If you'd gotten the lens a little earlier, you could have called it an artistic treatment and ribboned in the Posthumous challenge with it.
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12/04/2010 07:20:57 AM · #3 |
| Wow. That's pretty severe. Is that lens supposed to be subject to that much CA? |
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12/04/2010 07:42:08 AM · #4 |
"Purple fringing in harsh lighting situations, especially when wide open.", according to a google search. But, otherwise, supposed to be a lot of "bang for the buck".
You know the old sawâ¦A patient goes to see a doctor and complains that âit hurts when I do thisâ. To which the doctor replies somewhat simply, âThen stop doing thatâ! |
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12/04/2010 08:23:17 AM · #5 |
Originally posted by coryboehne:
I'm totally loving my new lens, but oh damn! can this thing produce some serious CA in certain situations..
Here's about the worst fringing I can imagine. This is a 1:1 crop..
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Welcome to the world of Fast glass.
Honestly I've shot with $5000 glass that wide open in situations would do that when shooting birds in trees with a bright sky behind it. I have a a $1500 85MM F1.2 that will do that to some extent although not as bad.
As Hahn said, if it bothers you that it does that, don't do that. :D
Matt |
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12/04/2010 08:26:01 AM · #6 |
Cool fringing wow. Apparently the Nikon version of this lens also has CA problems wide open, i have an 85 sigma 1.4 and in the wrong lighting wide open it has slight purple fringing but i haven't tried it in harsh light like this.
Just wait until there is a purple challenge, we got no chance if you enter.
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12/04/2010 08:42:43 AM · #7 |
| shoot in black and white. problems solved. your welcome. |
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12/04/2010 09:17:25 AM · #8 |
Originally posted by Yo_Spiff:
If you'd gotten the lens a little earlier, you could have called it an artistic treatment and ribboned in the Posthumous challenge with it. |
Ouch.
And ROFL.
Message edited by author 2010-12-04 09:23:49. |
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12/04/2010 09:23:26 AM · #9 |
Originally posted by MattO:
Originally posted by coryboehne:
I'm totally loving my new lens, but oh damn! can this thing produce some serious CA in certain situations..
Here's about the worst fringing I can imagine. This is a 1:1 crop..
|
Welcome to the world of Fast glass.
Honestly I've shot with $5000 glass that wide open in situations would do that when shooting birds in trees with a bright sky behind it. I have a a $1500 85MM F1.2 that will do that to some extent although not as bad.
As Hahn said, if it bothers you that it does that, don't do that. :D
Matt |
Yeah, stop taking pictures with it Cory, that'll solve your problems. Not the best advice I have seen here on DPC.
Have you tried closing it down? Results?
Sometimes just moving to the left or right will change the intensity of the CA.
I resolve my CA by minimizing the purple and magenta sliders in Lightroom or Camera RAW. Very simple and it works great.
Funny thing though. I sometimes use an old 50mm f1.4 OM lens at wide open and I have zero CA. I use my new Sigma 105mm f2.8 and I get plenty of it. Why? Glass quality? One thing I noticed is that the UV coating, or whatever it was, is almost completely gone so that may be why I don't see any. Do you think that today's CA is caused partly by the numerous layers of chemicals that are used to coat modern lenses?
I know that CA is caused by refractive index and the limiting power of each lens to focus most of the colours of the spectrum at a single point. I'm just saying that it may be exaggerated by the layers of chemicals.
Message edited by author 2010-12-04 09:30:32. |
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12/04/2010 11:44:15 AM · #10 |
This is longitudinal CA. Basically it means that stuff in front of the focus plane will be fringed in one color, and behind it will be fringed in the complementary color.
All ultra-fast lenses will do this to some extent, and the example is a worst-case scenario, shot wide open with a very bright BG light source and OOF objects silhouetted against it. Notice how the fringing is apparently absent where the BG isn't blown? The fun part is, it is still there. To see it, do a curves adjustment, grabbing the upper right handle and dragging it left (or do levels, dragging the white point to the left. You will find that the non-fringed portion of the object eventually looks just like the fringed one.
The key here is to avoid badly blown areas with sharp transitions to darkness. If you wind up with a situation like this, select the area and desaturate magenta. Repeat for the cyan. Done.
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12/04/2010 12:12:41 PM · #11 |
Hehe, thanks for the help & advice..
In the end I mostly find it just amusing, I was well aware of the reports of CA before I bought - I was just a tad surprised at just exactly how much CA this baby can throw down..
And, Matt- If you ever find yourself needed a faster focusing lens with more excellent CA, let me know, we can trade if you'd like :) |
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12/04/2010 06:33:08 PM · #12 |
Originally posted by Jac:
Originally posted by MattO:
Originally posted by coryboehne:
I'm totally loving my new lens, but oh damn! can this thing produce some serious CA in certain situations..
Here's about the worst fringing I can imagine. This is a 1:1 crop..
|
Welcome to the world of Fast glass.
Honestly I've shot with $5000 glass that wide open in situations would do that when shooting birds in trees with a bright sky behind it. I have a a $1500 85MM F1.2 that will do that to some extent although not as bad.
As Hahn said, if it bothers you that it does that, don't do that. :D
Matt |
Yeah, stop taking pictures with it Cory, that'll solve your problems. Not the best advice I have seen here on DPC.
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I'm not sure where you come up with stop taking pictures with it, from what I said, but whatever. Avoiding shooting into situations like he did is what the phrase, if it bothers you that it does that in that situation, change the situation so it doesn't do that. |
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12/04/2010 06:40:24 PM · #13 |
Ouch! I've never seen that with mine, but then I tend to use fast glass for available light portraits rather than pointing into the sun...
Message edited by author 2010-12-04 18:40:43. |
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