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07-21-2009, 10:25 PM   #1
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Chromatic aberrations in 100mm macro?

Hey everyone,

I was very excited to receive my K-7, DA* 16-50mm 2.8 and D FA 100mm macro 2.8 today . It's my second DSLR kit... this spring I bought a Canon XSi but decided to upgrade to the Pentax... love the weather sealing, compact body, HD video etc.

I'm concerned that I may have a bad copy of the 100mm macro lens, but I'm not sure. A lot of my images have purple/blue fringes would seem to me to be quite obvious/distracting if blown up or printed at any decent size. However I haven't had a camera for 2 months, and I'm not experienced to begin with, so maybe I'm looking too closely? I know that some chromatic aberration is normal, but I don't recall seeing anything like this even on my ultra-cheap EF-S Canon lenses, so I thought I would check here to see what you guys think. Any comments would be much appreciated .
Below are some screenshots from within Lightroom.

Some thing in my front lawn:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture343.jpg

Leather jacket:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture338.jpg

Black text on whiteboard:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture342.jpg

Nylon string (this one is not extreme but still, I was surprised to see any purple in this image at all):
http://i888.photobucket.com/albums/ac90/mhuebert/Picture340.jpg

07-21-2009, 11:11 PM   #2
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QuoteOriginally posted by inwonderland Quote
Some thing in my front lawn:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture343.jpg

Leather jacket:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture338.jpg

Black text on whiteboard:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture342.jpg

Nylon string (this one is not extreme but still, I was surprised to see any purple in this image at all):
http://i888.photobucket.com/albums/ac90/mhuebert/Picture340.jpg
Page not found !
But now that you're here, go ahead and search through the billions of photos, images and videos on Photobucket.
07-21-2009, 11:25 PM   #3
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Ugh. Sorry about that.

Here is a link that works (I think): Chromatic aberration on 100mm pentax macro pictures by mhuebert - Photobucket

Might need to click "full size" when hovering over the images to see it big enough.
07-22-2009, 12:30 AM   #4
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QuoteOriginally posted by inwonderland Quote
Ugh. Sorry about that.

Here is a link that works (I think): Chromatic aberration on 100mm pentax macro pictures by mhuebert - Photobucket

Might need to click "full size" when hovering over the images to see it big enough.
I see heavy purple fringing at jacket and at exposure button corners purples are way too heavy, could it be the blue light source or using wrong white balance?.

Pictures are also blurry, but it might not be the lens. I humbly recommend using tripod and mirror lock also remote trigger especially when taking test pictures.

Best wishes.
Can.

07-22-2009, 09:11 AM   #5
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Hehe there was no blue light source on the jacket, that was sunlight. That's the problem.

Re: blurry -- don't have a tripod but I'll try taking some better shots.
07-22-2009, 09:38 AM   #6
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Couple of questions... I can't find any exif info and wonder what the aperture was. If wide open, I'd expect these results. The jacket, for instance is also blown out in the highlights and it is a high contrast situation. So, If we're wide open and over exposed we're gonna get such results.

However, if these shots are not wide open then the results aren't encouraging.

Regards,
Mike
QuoteOriginally posted by inwonderland Quote
Hehe there was no blue light source on the jacket, that was sunlight. That's the problem.

Re: blurry -- don't have a tripod but I'll try taking some better shots.
07-22-2009, 11:19 AM   #7
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No EXIF info, below f/4 I would call that level of pfing normal.
07-22-2009, 04:32 PM   #8
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Did you use a UV filter and lens hood, that may help?

07-22-2009, 07:03 PM   #9
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QuoteOriginally posted by gofour3 Quote
Did you use a UV filter and lens hood, that may help?
Don't think that does anything to change CA. In fact, most ordinary UV filters might even MAGNIFY them!
QuoteOriginally posted by inwonderland Quote
Hey everyone,

I was very excited to receive my K-7, DA* 16-50mm 2.8 and D FA 100mm macro 2.8 today . It's my second DSLR kit... this spring I bought a Canon XSi but decided to upgrade to the Pentax... love the weather sealing, compact body, HD video etc.

I'm concerned that I may have a bad copy of the 100mm macro lens, but I'm not sure. A lot of my images have purple/blue fringes would seem to me to be quite obvious/distracting if blown up or printed at any decent size. However I haven't had a camera for 2 months, and I'm not experienced to begin with, so maybe I'm looking too closely? I know that some chromatic aberration is normal, but I don't recall seeing anything like this even on my ultra-cheap EF-S Canon lenses, so I thought I would check here to see what you guys think. Any comments would be much appreciated .
Below are some screenshots from within Lightroom.

Some thing in my front lawn:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture343.jpg

Leather jacket:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture338.jpg

Black text on whiteboard:
http://i888.photobucket.com/albums/ac90/mhuebert/Picture342.jpg

Nylon string (this one is not extreme but still, I was surprised to see any purple in this image at all):
http://i888.photobucket.com/albums/ac90/mhuebert/Picture340.jpg
If you are shooting wide open at anything 1:4 magnification or more, then you are bound to have CA, regardless of what lens it is. I suggest shooting at f/5.6+ when doing macro, considering the bokeh won't change much. Such high magnification even makes lovely bokeh at f/15.
07-22-2009, 07:27 PM   #10
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QuoteOriginally posted by GLXLR Quote
Don't think that does anything to change CA. In fact, most ordinary UV filters might even MAGNIFY them!


If you are shooting wide open at anything 1:4 magnification or more, then you are bound to have CA, regardless of what lens it is. I suggest shooting at f/5.6+ when doing macro, considering the bokeh won't change much. Such high magnification even makes lovely bokeh at f/15.
I have been shooting mostly slide film since the early 70’s, using older Pentax K series equipment and have never come across this purple fringing issue. So it must either be a digital or newer lens issue??

I did read somewhere that using a UV filter and lens hood helped reduce the effects.
As I do not shoot digital I do not know if it is true, no harm in trying though.
07-22-2009, 07:59 PM   #11
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QuoteOriginally posted by gofour3 Quote
I have been shooting mostly slide film since the early 70ís, using older Pentax K series equipment and have never come across this purple fringing issue. So it must either be a digital or newer lens issue??

I did read somewhere that using a UV filter and lens hood helped reduce the effects.
As I do not shoot digital I do not know if it is true, no harm in trying though.
Not trying to be hostile. All i wanted to achieve was answer your question.
07-22-2009, 08:34 PM   #12
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Well as a DFA 100mm user, I would say your copy does exhibit a little more colour fringing than what I would deem as normal. Colour fringing when shooting specular reflections especially a wide apertures is pretty common but I personally think your lens does show a little too much of it. You may have had a poor copy here.
07-22-2009, 09:55 PM   #13
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QuoteOriginally posted by GLXLR Quote
Not trying to be hostile. All i wanted to achieve was answer your question.
No worries. It would be interesting to take a series of pictures with this lens using a digital and film camera to compare the results.
07-23-2009, 04:49 PM   #14
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A much better set of example photos

Thanks to everyone for your comments.

- Many of these were shot wide-open (I've posted a link to a much better image gallery w/ details of each shot)
- I am using a UV filter and lens hood

Picasa Web Albums - MH - Pentax D FA 1... -You can view as a slide show (I've put some of the exif details right in the captions) or download the full JPG.

All of these are using the K-7 with the D FA 100mm macro.

I'm still trying to find out whether my macro is a good or bad copy. I am already sending in my DA* 16-50mm to Pentax for a bad front focus issue and am wondering whether to include this one with it.
07-23-2009, 05:26 PM   #15
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First thing you should do is ditch the UV filter and re-test. A UV filter can cause all kinds of ill effects.

Regards,
Mike
QuoteOriginally posted by inwonderland Quote
- Many of these were shot wide-open (I've posted a link to a much better image gallery w/ details of each shot)
- I am using a UV filter and lens hood
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