pentax 12-24

lodi781 · 05-11-2008, 04:22 PM

I originally bought this lens for nighttime architecture shots. I tried using it for a landscape, and noticed purple fringing around the trees...anyone else have this problem? Or did I just get a bad copy?

Damn Brit · 05-11-2008, 06:42 PM

Was it wide open, maybe the lens hood?

lodi781 · 05-11-2008, 07:41 PM

it was wide open and I had a polarizer on it..could that of been it??

Wheatfield · 05-11-2008, 07:46 PM

Purple fringing is typically a function of the sensor.
Learn what conditions cause it (strongly backlit trees is a good way) and avoid those conditions when possible.
Or, learn how to retouch it in post processing when it pops up.

philmorley · 05-11-2008, 08:00 PM

try Bart's Notebook: Photoshop Helper Actions (PF updated V2.6) very good action for getting rid of it

creampuff · 05-11-2008, 08:02 PM

Originally posted by Wheatfield

Purple fringing is typically a function of the sensor.
Learn what conditions cause it (strongly backlit trees is a good way) and avoid those conditions when possible.
Or, learn how to retouch it in post processing when it pops up.

Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor?

lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section.

The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA.

lodi781 · 05-11-2008, 09:05 PM

Originally posted by creampuff

Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor?

lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section.

The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA.

Woops. sorry about that... I have read that it does have some issues with it. But, It is an awesome lens for night time shots, so I think i'll probably keep it...

axl · 05-12-2008, 12:20 AM

Originally posted by lodi781

Woops. sorry about that... I have read that it does have some issues with it. But, It is an awesome lens for night time shots, so I think i'll probably keep it...

DA 12-24 is a good ultra wide angle lens. Many other lenses do exhibit purple fringe, and unfortunately Pentax glass seems to be quite prone to this.
Read this thread https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/27059-what-do-...ax-lenses.html and you'll see.

Purple fringe is worst when:
a) it's high extremly high contras situation
b) lens is wide open
- stopping lens down to say f8 or f11 usually helps a bit, but you have be carefull where you point your lens on bright day! otherwise it's possible to sort it out during PP ing, good luck

jeffkrol · 05-12-2008, 11:54 AM

Originally posted by creampuff

Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor?

lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section.

The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA.

One source, see the bottom dealing w "microlenses":
Chromatic Aberration: Optical: Glossary: Learn: Digital Photography Review

Wheatfield · 05-12-2008, 04:33 PM

Originally posted by creampuff

Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor?

lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section.

The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA.

See:
Chromatic Aberration: Optical: Glossary: Learn: Digital Photography Review
Purple fringing - Wikipedia, the free encyclopedia

It can be CA, it can also be an artifact of the sensor. The smart boys on PDML are pretty much of the opinion it is more often a sensor artifact than a lens artifact.
FWIW, I haven't had any PF problems with my 12-24 with either the istD, K10 or K20.

creampuff · 05-13-2008, 12:10 AM

If purple fringing is at the level of the sensor, than how would we account for the fact that lenses other than Pentax mounted on Pentax DSLRs exhibit very little or negligible purple fringing? The Voigtlander 125mm is an excellent example in this regard.

If by the proposition that it is caused by the microlenses in front of the sensor, then shots taken with such a lens would exhibit PF throughout the image, which is clearly not the case.

**NaClH2O** · 05-13-2008, 04:05 AM

lodi
Before I bought my 12-24, I did some massive searching on the web for info. From what I can tell, there seems to be a few copies of this lens that exhibit a LOT more PF than most. Some PF would be normal, but a lot isn't. I would check other shots from this lens, (try pbase, flick'r etc) if you feel you lens has more that what others show I'd exchange it. I was relatively lucky, I got a good copy. Note that from what I can find, a copy with bad PF is "relatively" rare. Here is a link to a thread I made when I first got this lens
https://www.pentaxforums.com/forums/post-your-photos/19438-lba-pentax-da-12-24mm-f4-0-a.html
This would be a good place to start.

NaCl(hope this helps)H2O

Wheatfield · 05-13-2008, 07:36 AM

Originally posted by creampuff

If purple fringing is at the level of the sensor, than how would we account for the fact that lenses other than Pentax mounted on Pentax DSLRs exhibit very little or negligible purple fringing? The Voigtlander 125mm is an excellent example in this regard.

If by the proposition that it is caused by the microlenses in front of the sensor, then shots taken with such a lens would exhibit PF throughout the image, which is clearly not the case.

That would depend on if the "tester" is tormenting PF out of the camera during individual testes. Also note, PF can be caused by either the sensor or the lens. I talk to some pretty smart optical guys who tend to believe it is more often sensor than lens.
I know who I believe.

lodi781 · 05-14-2008, 05:08 PM

I'll check that stuff out, thanks for all the tips everyone...

05-11-2008, 04:22 PM	#1
lodi781 Senior Member Join Date: Mar 2008 Location: southern CT Posts: 219	pentax 12-24 I originally bought this lens for nighttime architecture shots. I tried using it for a landscape, and noticed purple fringing around the trees...anyone else have this problem? Or did I just get a bad copy?

05-12-2008, 12:20 AM	#8
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	Keep It Originally posted by lodi781 Woops. sorry about that... I have read that it does have some issues with it. But, It is an awesome lens for night time shots, so I think i'll probably keep it... DA 12-24 is a good ultra wide angle lens. Many other lenses do exhibit purple fringe, and unfortunately Pentax glass seems to be quite prone to this. Read this thread https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/27059-what-do-...ax-lenses.html and you'll see. Purple fringe is worst when: a) it's high extremly high contras situation b) lens is wide open - stopping lens down to say f8 or f11 usually helps a bit, but you have be carefull where you point your lens on bright day! otherwise it's possible to sort it out during PP ing, good luck

05-11-2008, 06:42 PM	#2
Damn Brit Guest	Was it wide open, maybe the lens hood?

05-11-2008, 07:41 PM	#3
lodi781 Senior Member Join Date: Mar 2008 Location: southern CT Posts: 219 Original Poster	it was wide open and I had a polarizer on it..could that of been it??

05-11-2008, 07:46 PM	#4
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Purple fringing is typically a function of the sensor. Learn what conditions cause it (strongly backlit trees is a good way) and avoid those conditions when possible. Or, learn how to retouch it in post processing when it pops up.

05-11-2008, 08:00 PM	#5
philmorley Veteran Member Join Date: Mar 2007 Location: in a house in Armidale, Australia Posts: 472	try Bart's Notebook: Photoshop Helper Actions (PF updated V2.6) very good action for getting rid of it

05-11-2008, 08:02 PM	#6
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953	Originally posted by Wheatfield Purple fringing is typically a function of the sensor. Learn what conditions cause it (strongly backlit trees is a good way) and avoid those conditions when possible. Or, learn how to retouch it in post processing when it pops up. Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor? lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section. The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA.

05-11-2008, 09:05 PM	#7
lodi781 Senior Member Join Date: Mar 2008 Location: southern CT Posts: 219 Original Poster	Originally posted by creampuff Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor? lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section. The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA. Woops. sorry about that... I have read that it does have some issues with it. But, It is an awesome lens for night time shots, so I think i'll probably keep it...

05-12-2008, 11:54 AM	#9
jeffkrol Veteran Member Join Date: Sep 2006 Location: Wisconsin USA Photos: Gallery Posts: 8,434	Originally posted by creampuff Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor? lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section. The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA. One source, see the bottom dealing w "microlenses": Chromatic Aberration: Optical: Glossary: Learn: Digital Photography Review

05-12-2008, 04:33 PM	#10
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by creampuff Wheatfield, where in the world did you get the idea that purple fringing is a function of the sensor? lodi781 I think since this is a lens related question, it ought to have been posted at the Pentax SLR Lens Discussion section. The PF is in the lens design. This lens was co-developed with Tokina. The Tokina 12-24mm also has similar issues relating to CA. See: Chromatic Aberration: Optical: Glossary: Learn: Digital Photography Review Purple fringing - Wikipedia, the free encyclopedia It can be CA, it can also be an artifact of the sensor. The smart boys on PDML are pretty much of the opinion it is more often a sensor artifact than a lens artifact. FWIW, I haven't had any PF problems with my 12-24 with either the istD, K10 or K20.

05-13-2008, 12:10 AM	#11
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953	If purple fringing is at the level of the sensor, than how would we account for the fact that lenses other than Pentax mounted on Pentax DSLRs exhibit very little or negligible purple fringing? The Voigtlander 125mm is an excellent example in this regard. If by the proposition that it is caused by the microlenses in front of the sensor, then shots taken with such a lens would exhibit PF throughout the image, which is clearly not the case.

05-13-2008, 04:05 AM	#12
NaClH2O Site Supporter Join Date: Sep 2006 Location: Bronx NY Photos: Gallery \| Albums Posts: 5,631	lodi Before I bought my 12-24, I did some massive searching on the web for info. From what I can tell, there seems to be a few copies of this lens that exhibit a LOT more PF than most. Some PF would be normal, but a lot isn't. I would check other shots from this lens, (try pbase, flick'r etc) if you feel you lens has more that what others show I'd exchange it. I was relatively lucky, I got a good copy. Note that from what I can find, a copy with bad PF is "relatively" rare. Here is a link to a thread I made when I first got this lens https://www.pentaxforums.com/forums/post-your-photos/19438-lba-pentax-da-12-24mm-f4-0-a.html This would be a good place to start. NaCl(hope this helps)H2O

05-13-2008, 07:36 AM	#13
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by creampuff If purple fringing is at the level of the sensor, than how would we account for the fact that lenses other than Pentax mounted on Pentax DSLRs exhibit very little or negligible purple fringing? The Voigtlander 125mm is an excellent example in this regard. If by the proposition that it is caused by the microlenses in front of the sensor, then shots taken with such a lens would exhibit PF throughout the image, which is clearly not the case. That would depend on if the "tester" is tormenting PF out of the camera during individual testes. Also note, PF can be caused by either the sensor or the lens. I talk to some pretty smart optical guys who tend to believe it is more often sensor than lens. I know who I believe.

05-14-2008, 05:08 PM	#14
lodi781 Senior Member Join Date: Mar 2008 Location: southern CT Posts: 219 Original Poster	I'll check that stuff out, thanks for all the tips everyone...