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Orio
Joined: 24 Feb 2007 Posts: 29545 Location: West Emilia
Expire: 2012-12-04
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Posted: Sat Apr 28, 2007 3:26 pm Post subject: |
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Orio wrote:
lulalake wrote: |
HI Orio,
Ca and bloom(fringing) are two different issues. CA happens when a lens can't focus red and blue light at the same point, which must be corrected in all lenses as red and blue don't focus at the same point.
CA looks like there is a small halo of red on one side of any and all objects in the picture and a halo of green or blue on the other side
Fringing/blooming is specific to digital cameras. It occurs in high contrast-opposite color areas such as tree branches against sky, the rail against the sky etc etc.
All digital cameras experience this, it's just the degree of it that is what is in question. CMOS sensors tend to have less than CCDs, large individual sensors tend to have less than small ones.
There are PS actions that get rid of it pretty well if it is bothersome.
Jules |
hi Jules
I was suspecting something like this, that is why I mentioned pixel bleeding in the sensor, although it may not be precisely what you say. But it was just too strange for an optical problem like CA to stop suddenly just because there is less contrast. Also the thing that the red bleeding on the fence happens on both sides.
What does not fit in the picture for me is that I have not noticed such bad problem with other lenses, just with this one. So if it is a sensor problem, why does not show up with other lenses too?
I can not figure out this.
So symptoms do not match the CA, but at the same time, a sensor problem would be noticed with other lenses not just this one.
What is the answer that can make all pieces of the puzzle fit? _________________ Orio, Administrator
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lulalake
Joined: 22 Apr 2007 Posts: 1191 Location: Near Austin Texas
Expire: 2011-11-18
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Posted: Sat Apr 28, 2007 4:11 pm Post subject: |
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lulalake wrote:
[quote="Orio"] So symptoms do not match the CA, but at the same time, a sensor problem would be noticed with other lenses not just this one.
What is the answer that can make all pieces of the puzzle fit? [/quote]
I think higher contrast lenses exascerbate the issue. Try a high contrast lens on branches against a blue sky then a low contrast lens on the same scene.
You might see more fringing with the high contrast lens.
Cheers
Jules |
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LucisPictor
Joined: 26 Feb 2007 Posts: 17633 Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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Posted: Sat Apr 28, 2007 7:22 pm Post subject: |
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LucisPictor wrote:
CA and "bleeding" cause similar optical errors but in different colours, as far as I know.
CA is red/cyan and "bleeding" is blue/yellow, or the other way around. I keep confusing that.
As to the pictures:
- You shot this photos with a high f-number, since the dust spots on the sensor are clearly visible and the DoF is wide.
- The 2nd picture shows an even more closed aperture.
- Sharpness is excellent - in both cases.
- Colurs are are vivid but still seem to be genuine.
- CA (or bleeding) is visible but only very slightly - no problem at all.
So either this is quite an approved lens and these pictures proof its quality or it is a lens of which nobody of us would have expected such a performance.
And you wanted to "flabbergast" us... (I have a certain feeling that the latter is true!)
Carsten _________________ Personal forum activity on pause every now and again (due to job obligations)!
Carsten, former Moderator
Things ON SALE
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Orio
Joined: 24 Feb 2007 Posts: 29545 Location: West Emilia
Expire: 2012-12-04
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Posted: Sat Apr 28, 2007 7:57 pm Post subject: |
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Orio wrote:
LucisPictor wrote: |
So either this is quite an approved lens and these pictures proof its quality or it is a lens of which nobody of us would have expected such a performance.
And you wanted to "flabbergast" us... (I have a certain feeling that the latter is true!)
Carsten |
What is flabbergast?
Anyway, no, I just wanted to surprise you, because I imagined you would have mentioned 135mm format lenses, and I wanted to just say "No! This is not a normal lens, it's a Flek wideangle - but shooting as a normal lens on the 5D"
Just that, a very silly entertainment number
_________________ Orio, Administrator
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NE CEDE MALIS AUDENTIOR ITO
Ferrania film is reborn! http://www.filmferrania.it/
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peterqd
Joined: 28 Feb 2007 Posts: 7448 Location: near High Wycombe, UK
Expire: 2014-01-04
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Posted: Sat Apr 28, 2007 8:08 pm Post subject: |
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peterqd wrote:
Orio wrote: |
What is flabbergast? |
This is English slang that Carsten must have picked up when he was visiting the not-so-touristy places in Kent
"I'm flabbergasted" = "I'm amazed" or "I'm really surprised"
An even less-refined way of saying it is "I'm gobsmacked!"
You're learning some strange English words today Orio |
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Orio
Joined: 24 Feb 2007 Posts: 29545 Location: West Emilia
Expire: 2012-12-04
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Posted: Sat Apr 28, 2007 8:20 pm Post subject: |
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Orio wrote:
Ok then I wanted to flabbergast you _________________ Orio, Administrator
T*
NE CEDE MALIS AUDENTIOR ITO
Ferrania film is reborn! http://www.filmferrania.it/
Support the Ornano film chemicals company and help them survive!
http://forum.mflenses.com/ornano-chemical-products-t55525.html |
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LucisPictor
Joined: 26 Feb 2007 Posts: 17633 Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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Posted: Sun Apr 29, 2007 9:54 am Post subject: |
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LucisPictor wrote:
_________________ Personal forum activity on pause every now and again (due to job obligations)!
Carsten, former Moderator
Things ON SALE
Carsten = "KAPCTEH" = "Karusutenu" | T-shirt?.........................My photos from Emilia: http://www.schouler.net/emilia/emilia2011.html
My gear: http://retrocameracs.wordpress.com/ausrustung/
Old list: http://forum.mflenses.com/viewtopic.php?t=65 (Not up-to-date, sorry!) | http://www.lucispictor.de | http://www.alensaweek.wordpress.com |
http://www.retrocamera.de |
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bob955i
Joined: 15 Apr 2007 Posts: 2495
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Posted: Sun Apr 29, 2007 1:42 pm Post subject: |
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bob955i wrote:
Our gast has been duly flabbered..... |
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