Can K5 casue moire?

TropicalMonkey · 01-27-2013, 07:41 PM

Can K5 cause moire?

I was playing with my new K5 and I see some "rainbow effect" on my daughter's hair.
This picture was taken with flash on. Is this because of flash light or is it moire?

Thanks

Edit: tried to correct title spelling, but I could not!

Attached Images

Adam · 01-27-2013, 07:48 PM

In this case I think it's because of the light being reflected, but to answer your question, yes, moire is possible with the K-5, though you're probably never going to see it. We were able to provoke it using a test chart when we did the K-5 IIs review, though.

Dr_who · 01-28-2013, 03:28 PM

Yes I've seen it a few times on suits with fine patterns on the K5.

DevKom · 01-29-2013, 11:19 AM

I think it's *diffraction* not moiré, whereby the microscopic structure of the hair shafts are acting like micro prisms,
reflecting the light of the flash at different wavelengths giving the rainbow effect.
As in Diffraction Grating: Diffraction grating - Wikipedia, the free encyclopedia
That's my theory and I am sticking to it! ;-)

**jbinpg** · 01-29-2013, 12:48 PM

I agree. Same physical reason for the colour of many bird feathers such as hummingbird gorgets. Pure feather pigments other than black (melanin) and white are rare.

cbaytan · 01-30-2013, 03:04 PM

With or without AA filter any camera can produce moire, and IMO your case is not moire.

**Digitalis** · 02-05-2013, 06:06 AM

That isn't moire.

There is also an effect that is common in digital cameras and it is called false colour, it is really common with all cameras (not just ones without AA filters) - it usually occurs when there is an extremely sharp lens that provides detail but there aren't enough pixels to record it properly, so the demosaic algorithm just constructs the image with what information it has at its disposal and sometimes that construction is shall we say, less than accurate.

Another explanation is subsurface scattering, hair is at least partly translucent and light that strikes the surface also travels through it to some extent and in the process it gets scattered - like a tiny prism and the camera will pick up the scattered reflections. The colouration of bird feathers work by the use of Pigmentation or by the use of microscopic structures that create iridescence that are caused by naturally evolved diffraction gratings.

**gaweidert** · 02-06-2013, 08:10 PM

I do think it is a digital artifact. I don't think that you would ever see that artifact in film. Pixels just don't have the resolution of film. They don't really do a good job on tiny specular highlights. The colors are really there, but the way the image is processed distorts what is actually there a bit. Same sort of thing that causes purple fringe.

TropicalMonkey · 02-06-2013, 08:44 PM

Originally posted by gaweidert

I do think it is a digital artifact. I don't think that you would ever see that artifact in film. Pixels just don't have the resolution of film. They don't really do a good job on tiny specular highlights. The colors are really there, but the way the image is processed distorts what is actually there a bit. Same sort of thing that causes purple fringe.

I have seen the kind of purple fringing as shown here (Wikipedia) many times on my K5. One reason may be that this is the highest resolution camera I ever owned (compared to K100D, Canon G2 etc) and I find myself doing a lot of pixel peeping now-a-days :-)

01-27-2013, 07:41 PM	#1
TropicalMonkey Veteran Member Join Date: Nov 2012 Location: Saint Paul Posts: 304	Can K5 casue moire? Can K5 cause moire? I was playing with my new K5 and I see some "rainbow effect" on my daughter's hair. This picture was taken with flash on. Is this because of flash light or is it moire? Thanks Edit: tried to correct title spelling, but I could not! Attached Images

01-27-2013, 07:48 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	In this case I think it's because of the light being reflected, but to answer your question, yes, moire is possible with the K-5, though you're probably never going to see it. We were able to provoke it using a test chart when we did the K-5 IIs review, though. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
K01 have similar color/pattern moire as K5 IIs?	lanx0003	Pentax K-01	14	11-24-2012 04:59 AM
K5-IIs and Moiré	troenaas	Photographic Industry and Professionals	31	09-22-2012 04:40 AM
Can I thether My K5 in LR3?	Deiberson	Pentax K-5 & K-5 II	47	11-22-2011 04:40 PM
Got a K5 for $950! Can't believe it! Can I get the sensor stain fixed?	crossover37	Pentax K-5 & K-5 II	32	05-13-2011 05:04 PM

01-28-2013, 03:28 PM	#3
Dr_who Veteran Member Join Date: Jun 2009 Location: Edmonton, Alberta, Canada Photos: Gallery \| Albums Posts: 777	Yes I've seen it a few times on suits with fine patterns on the K5.

01-29-2013, 11:19 AM	#4
DevKom Junior Member Join Date: Jan 2011 Location: Essen, NRW Photos: Gallery Posts: 47	I think it's diffraction not moiré, whereby the microscopic structure of the hair shafts are acting like micro prisms, reflecting the light of the flash at different wavelengths giving the rainbow effect. As in Diffraction Grating: Diffraction grating - Wikipedia, the free encyclopedia That's my theory and I am sticking to it! ;-)

01-29-2013, 12:48 PM	#5
jbinpg Site Supporter Join Date: Mar 2008 Location: Prince George, BC Photos: Gallery \| Albums Posts: 3,546	I agree. Same physical reason for the colour of many bird feathers such as hummingbird gorgets. Pure feather pigments other than black (melanin) and white are rare.

01-30-2013, 03:04 PM	#6
cbaytan Inactive Account Join Date: Nov 2008 Location: Trabzon/Turkey Photos: Gallery Posts: 1,010	With or without AA filter any camera can produce moire, and IMO your case is not moire.

02-05-2013, 06:06 AM	#7
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	That isn't moire. There is also an effect that is common in digital cameras and it is called false colour, it is really common with all cameras (not just ones without AA filters) - it usually occurs when there is an extremely sharp lens that provides detail but there aren't enough pixels to record it properly, so the demosaic algorithm just constructs the image with what information it has at its disposal and sometimes that construction is shall we say, less than accurate. Another explanation is subsurface scattering, hair is at least partly translucent and light that strikes the surface also travels through it to some extent and in the process it gets scattered - like a tiny prism and the camera will pick up the scattered reflections. The colouration of bird feathers work by the use of Pigmentation or by the use of microscopic structures that create iridescence that are caused by naturally evolved diffraction gratings.

02-06-2013, 08:10 PM	#8
gaweidert Loyal Site Supporter Join Date: Mar 2012 Location: Rochester, NY Photos: Gallery Posts: 5,325	I do think it is a digital artifact. I don't think that you would ever see that artifact in film. Pixels just don't have the resolution of film. They don't really do a good job on tiny specular highlights. The colors are really there, but the way the image is processed distorts what is actually there a bit. Same sort of thing that causes purple fringe.

02-06-2013, 08:44 PM	#9
TropicalMonkey Veteran Member Join Date: Nov 2012 Location: Saint Paul Posts: 304 Original Poster	Originally posted by gaweidert I do think it is a digital artifact. I don't think that you would ever see that artifact in film. Pixels just don't have the resolution of film. They don't really do a good job on tiny specular highlights. The colors are really there, but the way the image is processed distorts what is actually there a bit. Same sort of thing that causes purple fringe. I have seen the kind of purple fringing as shown here (Wikipedia) many times on my K5. One reason may be that this is the highest resolution camera I ever owned (compared to K100D, Canon G2 etc) and I find myself doing a lot of pixel peeping now-a-days :-)