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Awful chromatic aberration with Oly 45 1.8

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I've seen worse longitudinal CA in photos taken with the 4/3 50mm f/2.0 macro lens.

I think that aspherical lens elements are used to correct LoCA, and the 45mm f/1.8 doesn't have any; I guess that's why it's less expensive than the Panasonic Leica-co-branded lenses which do have aspherical elements.
 
weesam said:
Lens deficiencies such as chromatic aberration and distortion etc, although they exist, are never bothersome on decent photos.

They tend to be bothersome on awful photos - ones that are so compositionally and artistically empty that you have to look at individual pixels to find something of note.
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Dude, it's just a test shot, the poster didn't claim it was a work of art. People are allowed to test their equipment, and this is a technical gear-oriented forum. If you don't want to read message threads like this, then you're in the wrong place.
weesam said:
You could send it back. Or take better pictures and not worry about it. Or even better, fix it in a photo-editing programme. It's just a case of moving a slider a few pixels across a screen.
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You can't fix longitudinal CA with sliders. You're confusing it with lateral CA.

HOWEVER--weesam does have a point that, when you use these lenses for portraits, you rarely notice the longitudinal CA. You're not really supposed to take landscape photos during the day with the lens wide open.
 
Thanks sigala1

To be honest I get tired of the amount of gearheads on this forum and wished it was a bit more like my experience here when the forum started and I had my first Fuji digicam.

However this seemed the perfect place to ask a question like I did — and why would I have noticed it in a good photo unless I was some kind of pixel peeper? Therefore surely the guy was contradicting himself? You just can't win here.

Just to prove I can take a photo:

http://www.flickr.com/photos/jamescarruthers/sets/72157628364281811/
http://www.flickr.com/photos/jamescarruthers/sets/72157627644595185/

Thanks everyone for your replies — I'm satisfied there's nothing wrong with the lens and will be keeping it for sure — I've been very happy with the other shots I've used it for.

--
Former SLR junkie, m43 convert.
 
m4/3 lenses are not optically corrected to reduce CA.

Panasonic relies on in-camera software corrections to reduce CA and distortion.
Olympus only correct distortion, but not CA in-camera.

Even the "Leica" branded 25mm f/1.4 shows a fairly large amount of CA :
http://www.slrgear.com/reviews/showproduct.php/product/1439/cat/68

The panasonic 14 and 20mm are even worse :
http://www.slrgear.com/reviews/showproduct.php/product/1389/cat/68
http://www.slrgear.com/reviews/showproduct.php/product/1295/cat/68

The Oly 45mm is actually pertty good for CA among m4/3 lenses. It only shows CA wide open, but stopped down to f/4 it's hardly noticeable :

http://www.slrgear.com/reviews/showproduct.php/product/1443/cat/14

Don't send your lens back, because the amount of CA in your picture is pretty normal, and you will not notice in in normal sized print.

And if it really bothers you, you can easily corrected it with any picture editing software.

--
Cheers,

Frederic
http://azurphoto.com/blog/
 
...using the Kekus LensFix CI (or Cl -- whatever!) plug-in, in my case in PhotoLine on Mac. It's a P'shop compatible plug-in. The equivalent (indeed, the same database) is available as PTLens for Windows. (It's lens distortion correction software.) The adjsutment (as I thnk someone has mentioned) is quite simple. Just move the slider a little.

But as you can see, some of it is not fixable.

I'm posting this assuming your permission since it is a matter under discussion. If you don't want me to post it and to have your picture, labelled as your picture, in my gallery, please say so and I'll remove it immediately.





I would be interested in seeing a series of pix of this nature running down the aperture scale. I have the lens and I have seagulls, but I haven’t brought the too as close together as you have -- and I doubt if I can! Besides which, I'm not free to attempt the feat for a coupla daze. :O

Might try a white flower in the morning, though.

Cheers, geoff
--
Geoffrey Heard
http://pngtimetraveller.blogspot.com/2011/10/return-to-karai-komana_31.html
 
Thanks for the links — it really puts it in perspective :)

--
Former SLR junkie, m43 convert.
 
Geoff,

No problem at all with you using the image — thanks for showing me this.

The gulls always line up like that there — The Serpentine in Hyde Park, London :)

--
Former SLR junkie, m43 convert.
 
Pixnat2 said:
m4/3 lenses are not optically corrected to reduce CA.
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They certainly are.
Pixnat2 said:
Panasonic relies on in-camera software corrections to reduce CA and distortion.
Olympus only correct distortion, but not CA in-camera.
Click to expand...
Panasonic bodies will software-correct lateral CA on Panasonic lenses. Longitudinal CA (which is what the OP is talking about) is not software-corrected. Nor is lateral CA software-corrected unless the body-lens combination is 100 percent Panasonic.
Pixnat2 said:
Even the "Leica" branded 25mm f/1.4 shows a fairly large amount of CA :
http://www.slrgear.com/reviews/showproduct.php/product/1439/cat/68

The panasonic 14 and 20mm are even worse :
http://www.slrgear.com/reviews/showproduct.php/product/1389/cat/68
http://www.slrgear.com/reviews/showproduct.php/product/1295/cat/68

The Oly 45mm is actually pertty good for CA among m4/3 lenses. It only shows CA wide open, but stopped down to f/4 it's hardly noticeable :

http://www.slrgear.com/reviews/showproduct.php/product/1443/cat/14
Click to expand...
None of these tests measure what the OP is concerned about, i.e. longitudinal CA in the out-of-focus area.
Pixnat2 said:
Don't send your lens back, because the amount of CA in your picture is pretty normal, and you will not notice in in normal sized print.
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It's good advice not to send back the lens because a) there is most likely nothing wrong with it, and b) other available lenses of similar focal length and speed are unlikely to be any better.
Pixnat2 said:
And if it really bothers you, you can easily corrected it with any picture editing software.
Click to expand...
No. The type of CA that the OP is talking about cannot be corrected all that easily or all that well. Lateral CA, by contrast, can easily be corrected with close to perfect results.

A good explanation of different types of CA and their visual manifestations is provided here:

http://toothwalker.org/optics/chromatic.html

and here

http://toothwalker.org/optics/bokeh.html
 
the lens is not sold as being apochromatic. If you dont want these color fringes to appear on OOF contrasty edges, you need an apochromatic lens, and of course to pay the price for it (maybe 2 to 5 times the price of a normal lens). It's usually high end macro lenses.
Otherwise a bit of LOCA with such a wide aperture is far from shocking.
 
Surefoot said:
the lens is not sold as being apochromatic. If you dont want these color fringes to appear on OOF contrasty edges, you need an apochromatic lens, and of course to pay the price for it (maybe 2 to 5 times the price of a normal lens). It's usually high end macro lenses.
Otherwise a bit of LOCA with such a wide aperture is far from shocking.
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From what I've read the term apochromatic only applies to the image plane - no LoCA in the image plane. It is still possible to have "LoCA" in front of or behind the image plane in an apochromat (and that's what the OP is experiencing). Of course the better corrected the lens the more likely it may be that the out of focus areas are also well corrected, but I don't think it is strictly necessary for an apochromat. Most of these terms are only defined for the image plane (in fact LoCA itself is only defined in the image plane, which is why I used quotes above). Interestingly sometimes these out of focus area fringes are actually more a function of the aberration that causes LatCA than the one that causes LoCA despite the fact that they "look" a bit like "LoCa".

All that blather aside, I completely agree the OP shouldn't return the lens - it is relatively rare to find a wide aperture lens that doesn't do this - even if perfectly corrected at the image plane.
--
Ken W
See plan in profile for equipment list
 
kenw said:
Interestingly sometimes these out of focus area fringes are actually more a function of the aberration that causes LatCA than the one that causes LoCA despite the fact that they "look" a bit like "LoCa".
Click to expand...
Not quite sure of what you mean by that Ken. According to a favorite source of both of us, LaCa when seen in the OOF area would typically manifest itself as differently colored fringes on either side of the same blur disk (magenta on one side, green on the other) rather than as a monochrome fringe (magenta in front of the focus point, green behind) as in the image presented by the OP as well as virtually all others I have seen.

http://toothwalker.org/optics/bokeh.html
 
You're absolutely right Anders. I just meant that just because it is "blurry" doesn't mean it is LoCA once you are in an out of focus area - probably an obvious point that wasn't worth my making. And I think you are correct as well about how most lenses behave - most obvious examples I've seen are of the "LoCA" variety with the fringing changing color based on being in front of or behind the image plane.

Ken
Anders W said:
kenw said:
Interestingly sometimes these out of focus area fringes are actually more a function of the aberration that causes LatCA than the one that causes LoCA despite the fact that they "look" a bit like "LoCa".
Click to expand...
Not quite sure of what you mean by that Ken. According to a favorite source of both of us, LaCa when seen in the OOF area would typically manifest itself as differently colored fringes on either side of the same blur disk (magenta on one side, green on the other) rather than as a monochrome fringe (magenta in front of the focus point, green behind) as in the image presented by the OP as well as virtually all others I have seen.

http://toothwalker.org/optics/bokeh.html
Click to expand...
--
Ken W
See plan in profile for equipment list
 
kenw said:
And I think you are correct as well about how most lenses behave - most obvious examples I've seen are of the "LoCA" variety with the fringing changing color based on being in front of or behind the image plane.
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Oh yes. I have yet to see any exceptions to that particular rule. Since you can see the fringes pretty clearly on an m43 camera in enlarged "focus-assist" mode, I find them helpful as a focusing aid. If you see green fringes where you want your focus, you are front-focusing. If you see clear purple fringes, you are back-focusing. If you adjust focus such that the green fringe just disappears, you are right on.

On lenses that are less than perfectly corrected for LoCa in the in-focus area (as are virtually all fast "legacy" lenses), you are likely to see a bit of purple when the lens is perfectly in focus so I find it more helpful to concentrate on the green part. In order to see how much of a purple (sometimes even blueish) fringe to expect when the lens is perfectly focused, I have found it helpful as an exercise to focus on some really bright/white objects against, fully exposed to the sun, against a dark background, e.g. a white balcony rail or the like.
 
Fast aperture lenses always suffer LoCa at wide apertures, and I guess we will have to live with it for a while.

Your example looks completely fine to me, and I'd say that I would like to see the same behaviour from my Canon 85 1.8 USM. It's an excellent lens, really one of my favourite, but it suffers LoCa quite badly, and still, it only appears in certain circumstances.

Look here:





100% crop



 
For shooting completely wide open in a high contrast edge like that, I think that's rather well controlled.

--

Raist3d/Ricardo (Photographer, software dev.)- "You are taking life too seriously if it bugs you in some way that a guy quotes himself in the .sig quote" - Ricardo
 
JamesCarruthers said:
Not a brilliant photo - but it looks awful.

I haven't used the lens too much but noticed this for the first time yesterday.

Check out the coloured halos around the near and far out of focus birds — you may want to look at it full size.

Time to send the lens back?
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... for raising this issue. I wouldn't say 'awful' - but it's given rise to an interesting discussion and convinced me to get the lens! ;-)

... and frankly, when I see that effect in my photos I just use the desaturate brush along the outlines. Works for me!!

Mike
--
Mike Davis
Photographing the public for over 50 years
http://www.flickr.com/photos/watchman
 
I cant find it anymore but i read a nice article (talking about a macro lens i believe) that explained the OOF color corrections on apochromat lenses. Thought being apochromatic included such corrections as well (at least on macro lenses where OOF details appear most frequently) but maybe you're right, i dont think i own any apo lens to test this...
 
Surefoot said:
I cant find it anymore but i read a nice article (talking about a macro lens i believe) that explained the OOF color corrections on apochromat lenses. Thought being apochromatic included such corrections as well (at least on macro lenses where OOF details appear most frequently) but maybe you're right, i dont think i own any apo lens to test this...
Click to expand...
Actually, reading around more I think we are both "right". Optics and microscope type folks have a fairly strict definition of "apochromatic" and it only really has to do with the image plane and the number of points for which the residual spectrum is zero - that's what I was referring to. It is a nice precise definition and like most nice precise definitions probably isn't all that useful in a practical sense for a photographer!

Looking in the photographic industry the term has taken on a much fuzzier meaning of "well corrected" for color aberrations that is perhaps more relevant to a photographer. In that sense I think it is perfectly valid to expect aberrations outside the image plane to be one of the qualities an "apochromatic" photographic lens would try to achieve. So I think what you said originally probably is a better fit for the photographic context than what I was saying.

--
Ken W
See plan in profile for equipment list
 
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