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01-16-2013, 07:02 AM   #1
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Chromatic aberration at close range

Hi,

I have been ogling an old manual lens for sale, which I am interested in because it is wide (28mm), very compact and it focuses down (manually) to 40cm according to the focus ring.

But it is a no-name lens (Hanimex) and I am not sure it will give me acceptable results photographically.

The seller sent me some sample pictures. I am slightly concerned with CA in this picture which seems to have been taken fully open, probably at f/2.8. This is in the off-centre area of the photo. Is this expected?

The EXIF info I have says:
QuoteQuote:
Camera: Olympus E-PL1
Exposure: Auto exposure, Aperture-priority AE, 1/50 sec, ISO 320
Flash: Auto, Did not fire, Red-eye reduction
Date: January 16, 2013 2:15:11PM
Color Space: sRGB
Software: Version 1.1
File: 2,688 4,032 JPEG (10.8 megapixels, 4,891,708 bytes (4.7 megabytes) Image compression: 85%


Attached Images
 
01-16-2013, 07:36 AM   #2
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Good Morning Jido,
For you to compare:
Here is a test on printed paper with the Vivitar 28mm 1:2.0 Close Focus Wide Angle at f/2.8 and 400 mm.
The camera is same as yours: E_PL1 set also at 1/50th iso 320

(This Camera jpg is 4000 by 3000 and 7.5 MB)
https://www.box.com/s/guoigwwvca1kxf9w1fx0
01-16-2013, 08:11 AM   #3
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QuoteOriginally posted by wombat2go Quote
Good Morning Jido,
For you to compare:
Here is a test on printed paper with the Vivitar 28mm 1:2.0 Close Focus Wide Angle at f/2.8 and 400 mm.
The camera is same as yours: E_PL1 set also at 1/50th iso 320

(This Camera jpg is 4000 by 3000 and 7.5 MB)
https://www.box.com/s/guoigwwvca1kxf9w1fx0
Thanks. My sample photo has more marked CA but this shows some CA is expected.
01-16-2013, 08:41 AM   #4
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That doesn't even seem too bad, the sample seems to be not only 100% crop, but actually enlarged. Be sure to put on a good hood, shoot in raw and fix the aberration in post. Most of those old lenses also improve a lot if you stop down, even just one stop.

01-16-2013, 10:10 AM   #5
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A couple of points to note here.

first of all, some wide angle lenses, sigma Mini Wide II for example do exhibit significant lateral CA.

second there are programs that re-scale the three color layers to correct lateral CA so it can be dealt with to a great extent in PP. Both Pentax photo lab, and Adobe use this technique. Corel PSP does not, but there is a plug in PT lens which does.

when correcting lateral CA by layer rescaling, the sharpness of the image improves significantly
01-16-2013, 10:28 AM   #6
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With a wave of the magic wand...

Last edited by wildman; 01-20-2013 at 04:30 AM.
01-16-2013, 11:04 AM   #7
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QuoteOriginally posted by wildman Quote
With a wave of the magic wand...
Was this done using a CA tool that re-scaled the layers or a CA tool that removes fringes? It's hard to tell because the CA is at the pixel level so sharpness is very subjective
01-16-2013, 11:15 AM   #8
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QuoteOriginally posted by lowell goudge Quote
was this done using a ca tool that re-scaled the layers or a ca tool that removes fringes? It's hard to tell because the ca is at the pixel level so sharpness is very subjective
acr 7.2

01-21-2013, 08:04 AM   #9
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I received the lens. Loving the non-obstructive dimensions.

I tried to use it for snow pictures, but I was having a difficult time with Focus Peaking.

Here is a sample:


Lens on camera:
Attached Images
View Picture EXIF
IPhone 4  Photo 
01-21-2013, 08:29 AM   #10
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jido,
I see the scales are 1/4 turn off centre.
Is the lens "clicked" on the mount or did you loosen it for the shot?
01-21-2013, 08:40 AM   #11
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Now that I look at it, the lens does not seem to screw all the way in. I will try it with just the M42 adaptor and see if there is a problem.
01-21-2013, 09:23 AM   #12
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QuoteOriginally posted by jido Quote
Now that I look at it, the lens does not seem to screw all the way in. I will try it with just the M42 adaptor and see if there is a problem.
Don't worry about it too much if it is M42, they usually don't line up very well. As long as it sits flush against the body and doesn't wobble, it is fine.
01-21-2013, 10:00 AM   #13
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QuoteOriginally posted by elliott Quote
Don't worry about it too much if it is M42, they usually don't line up very well. As long as it sits flush against the body and doesn't wobble, it is fine.
All right, that's fine then.

It does not look flush against the body because it has a protrusion at the back.
01-21-2013, 12:57 PM   #14
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Looks good, and the IQ seems good. From that photo I can't see any fringing/lateral chrom ab. Just a note, because I see a few droplets on the camera, the lens has to be WR as well as the body, for the system to be WR. Now, those droplets aren't going to be a problem, this is just a disclaimer.
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