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**BigMackCam** · 07-09-2016, 06:01 AM

I've noticed this a couple of times before, but this is a pretty extreme example... I took this photo with my K-3 a couple of days ago. It was sunny, and there was sunlight shining directly onto our cat. Photo taken with the DA*60-250 wide open at f/4. If you look at the whiskers, and the fur to the upper left of the image, there are areas that a multi-coloured - red, magenta, yellow, green, blue etc. If I look really carefully, I can make this out at 1:2 and even 1:3 reproduction. The crops below are at 1:1 and 2:1 to show the effect at its worst. The photo is a raw DNG file viewed in Lightroom 6, but the effect is visible in DCU5 also.

Has anyone come across this effect before? Is it a K-3 or Pentax thing, or a general issue with digital sensors - or something else?

EDIT: Hang on... is this moiré I'm seeing? I can remove it using Lightroom's Moiré slider, it seems!

Attached Images

Last edited by BigMackCam; 07-09-2016 at 06:11 AM.

sundr · 07-09-2016, 07:09 AM

It may be moire but it may also be due to the structure of the cats fur causing different light waves to be reflected. It's been a long time since I studied biology but I don't think any black animal is absolutely black. It's common to see a shimmer of other colors. I wouldn't try to remove it. I don't see it as an artifact. Just my opinion.

Penumbra · 07-09-2016, 07:34 AM

You're overanalyzing because of that new 60-250 of yours (congrats btw)

Under direct sunlight, with the naked eye you'll see the same light effect on dark fur

**BigMackCam** · 07-09-2016, 07:42 AM

Originally posted by sundr

It may be moire but it may also be due to the structure of the cats fur causing different light waves to be reflected. It's been a long time since I studied biology but I don't think any black animal is absolutely black. It's common to see a shimmer of other colors. I wouldn't try to remove it. I don't see it as an artifact. Just my opinion.

Originally posted by Penumbra

You're overanalyzing because of that new 60-250 of yours (congrats btw)

Under direct sunlight, with the naked eye you'll see the same light effect on dark fur

Thanks, both

Well, that's yet another thing I've learned from these forums (though it sounds like perhaps I should have been listening closer in science classes

) - much appreciated!

**jbinpg** · 07-09-2016, 09:48 AM

It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera.

**BigMackCam** · 07-09-2016, 10:19 AM

Originally posted by jbinpg

It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera.

Thank you

Yes, in fact it does look very similar to the colour I see in starlings...

Not a Number · 07-09-2016, 10:49 AM

Take a strand of your hair and examine it in bright light - sunlight is ideal. Hair is translucent and the pigment and cell structure diffracts light in many ways.

**Pål Jensen** · 07-10-2016, 05:22 AM

Originally posted by jbinpg

It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera.

Maybe there's something wrong with the cat!

**BigMackCam** · 07-10-2016, 05:24 AM

Originally posted by Pål Jensen

Maybe there's something wrong with the cat!

I'll tell him you said this... He won't be amused!

**pepperberry farm** · 07-10-2016, 05:32 AM

we have black dogs and I will see a similar effect in them (both naked eye and photos) when in strong light (sunlight or artificial) - I would not consider this an issue with the lens or camera....

**BigMackCam** · 07-10-2016, 06:19 AM

Thanks, Dave... so long as I know it happens and isn't a problem, I'm cool with it. It's not that noticeable, and as I mentioned, the moiré slider in LR6 removes it effectively

**pepperberry farm** · 07-10-2016, 06:23 AM

Originally posted by BigMackCam

Thanks, Dave... so long as I know it happens and isn't a problem, I'm cool with it. It's not that noticeable, and as I mentioned, the moiré slider in LR6 removes it effectively

of course, you could always ask your model (cat) to move out of the sun.....

(:

**BigMackCam** · 07-10-2016, 06:32 AM - **1 Like**

Originally posted by pepperberry farm

of course, you could always ask your model (cat) to move out of the sun.....

I suspect that would be met with the same disregard as any other requests made of him... but I'll try. He's going through a mousing phase right now and seems to think "Put it down!" and "Let it go!" means "Bite down hard" or "Bring that inside the house!"

07-09-2016, 06:01 AM	#1
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704	Weird effect in images on K-3... anyone seen this before? I've noticed this a couple of times before, but this is a pretty extreme example... I took this photo with my K-3 a couple of days ago. It was sunny, and there was sunlight shining directly onto our cat. Photo taken with the DA60-250 wide open at f/4. If you look at the whiskers, and the fur to the upper left of the image, there are areas that a multi-coloured - red, magenta, yellow, green, blue etc. If I look really carefully, I can make this out at 1:2 and even 1:3 reproduction. The crops below are at 1:1 and 2:1 to show the effect at its worst. The photo is a raw DNG file viewed in Lightroom 6, but the effect is visible in DCU5 also. Has anyone come across this effect before? Is it a K-3 or Pentax thing, or a general issue with digital sensors - or something else? EDIT: Hang on... is this moiré I'm seeing? I can remove it using Lightroom's Moiré slider, it seems! Attached Images Last edited by BigMackCam; 07-09-2016 at 06:11 AM.*

07-09-2016, 07:09 AM	#2
sundr Senior Member Join Date: Jun 2012 Location: St. Paul, Minnesota Photos: Gallery Posts: 123	It may be moire but it may also be due to the structure of the cats fur causing different light waves to be reflected. It's been a long time since I studied biology but I don't think any black animal is absolutely black. It's common to see a shimmer of other colors. I wouldn't try to remove it. I don't see it as an artifact. Just my opinion. Last edited by sundr; 07-09-2016 at 07:21 AM.

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07-09-2016, 07:34 AM	#3
Penumbra Senior Member Join Date: Feb 2011 Location: Suceava, Romania Photos: Albums Posts: 139	You're overanalyzing because of that new 60-250 of yours (congrats btw) Under direct sunlight, with the naked eye you'll see the same light effect on dark fur

07-09-2016, 07:42 AM	#4
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704 Original Poster	Originally posted by sundr It may be moire but it may also be due to the structure of the cats fur causing different light waves to be reflected. It's been a long time since I studied biology but I don't think any black animal is absolutely black. It's common to see a shimmer of other colors. I wouldn't try to remove it. I don't see it as an artifact. Just my opinion. Originally posted by Penumbra You're overanalyzing because of that new 60-250 of yours (congrats btw) Under direct sunlight, with the naked eye you'll see the same light effect on dark fur Thanks, both Well, that's yet another thing I've learned from these forums (though it sounds like perhaps I should have been listening closer in science classes ) - much appreciated!

07-09-2016, 09:48 AM	#5
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera.

07-09-2016, 10:19 AM	#6
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704 Original Poster	Originally posted by jbinpg It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera. Thank you Yes, in fact it does look very similar to the colour I see in starlings...

07-09-2016, 10:49 AM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Take a strand of your hair and examine it in bright light - sunlight is ideal. Hair is translucent and the pigment and cell structure diffracts light in many ways.

07-10-2016, 05:22 AM	#8
Pål Jensen Site Supporter Join Date: Dec 2007 Location: Norway Photos: Albums Posts: 4,371	Originally posted by jbinpg It is refracted iridescence, same mechanism that gives many bird feathers their colour. Nothing wrong with your camera. Maybe there's something wrong with the cat!

07-10-2016, 05:24 AM	#9
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704 Original Poster	Originally posted by Pål Jensen Maybe there's something wrong with the cat! I'll tell him you said this... He won't be amused!

07-10-2016, 05:32 AM	#10
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,781	we have black dogs and I will see a similar effect in them (both naked eye and photos) when in strong light (sunlight or artificial) - I would not consider this an issue with the lens or camera....

07-10-2016, 06:19 AM	#11
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704 Original Poster	Thanks, Dave... so long as I know it happens and isn't a problem, I'm cool with it. It's not that noticeable, and as I mentioned, the moiré slider in LR6 removes it effectively

07-10-2016, 06:23 AM	#12
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,781	Originally posted by BigMackCam Thanks, Dave... so long as I know it happens and isn't a problem, I'm cool with it. It's not that noticeable, and as I mentioned, the moiré slider in LR6 removes it effectively of course, you could always ask your model (cat) to move out of the sun..... (:

07-10-2016, 06:32 AM - 1 Like	#13
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,704 Original Poster	Originally posted by pepperberry farm of course, you could always ask your model (cat) to move out of the sun..... I suspect that would be met with the same disregard as any other requests made of him... but I'll try. He's going through a mousing phase right now and seems to think "Put it down!" and "Let it go!" means "Bite down hard" or "Bring that inside the house!"

Weird effect in images on K-3... anyone seen this before?

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