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01-31-2010, 09:18 AM   #1
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k-x moire problem?

Sorry if this has been chewed over before...

I have been using my k-x for a week, and have so far been generally disappointed with the results when viewed at 100% on screen. There's something of a slight softness to them that I wouldn't expect - especially as I am using the 21, 40 and 70 limited lenses. They don't "sing" on the screen in the same way as images taken with my other cameras. I must admit I'm a bit sad about it, as I was so excited about getting this camera...

That aside, I've also had two instances of moire in a couple of hundred shots - which is two more than I've had in the past five years from literally 100,000s of shots with a Canon 5d, 1ds III, Sigma DP1 and DP2.

One from yesterday (cropped from original):



One from today:



Is this a problem that others have discovered with the k-x, and is there a workaround? I imagine it's to do with the anti alias filter, which I guess is quite light. But then why do I feel my images lack the fine detail and sharpness of even my 5mp DP2?

BTW I shoot raw and have been processing them in Lightroom 2.6.
Thanks
Retrogaz


Last edited by retrogaz; 01-31-2010 at 09:21 AM. Reason: problems uploading images
01-31-2010, 09:33 AM   #2
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can't see any images.
maybe try to repost or edit?

Jan Rinze.
01-31-2010, 10:17 AM   #3
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Oops

I'll try again...

Picasa Web Albums - gareth

Picasa Web Albums - gareth
01-31-2010, 12:19 PM   #4
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This could be the result of a bad RAW conversion setting.
I don't use Lightroom so i don't know how to set that up properly.
You could try out RawTherapee to see if that has the same results.
Could you make the raw files available so others can take a look at it?

Best regards,

Jan Rinze.

01-31-2010, 01:54 PM   #5
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Interesting. I've never seen such striking moire with my K-x, using Lightroom 2.5, or anything else.

Why not try shooting the same scenes in RAW+ and see if the in camera produced JPG's show the same issues. That might help answer whether it is a PP issue.
01-31-2010, 02:29 PM   #6
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Raw+

I'm very annoyed with myself that I didn't shoot in raw+. But moire twice in two days! That's not fair!!

I downloaded a trial of Capture One, and with the moire sliders on maximum was able to take much of it out.

I'll keep shooting and see if it occurs again.
01-31-2010, 02:31 PM   #7
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By the way Rawr...

How have you found overall sharpness/blur of the images? I'm trying to digest all the discussions on the internet about effect of mirror slap, shake reduction etc, and also what are the best settings for processing the images in LR 2.6. It would be good to know how you are finding things.
02-01-2010, 12:42 AM   #8
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This thread reminded me the photo I've taken yesterday, look at the angels sent pink light flood and the green one on the left of the pink. These light floods, rays whatever you call it don't show up in RAW, just exists in the jpeg file.

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02-01-2010, 05:14 AM   #9
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QuoteOriginally posted by cbaytan Quote
This thread reminded me the photo I've taken yesterday, look at the angels sent pink light flood and the green one on the left of the pink. These light floods, rays whatever you call it don't show up in RAW, just exists in the jpeg file.
I like your exposure...the snow is nicely white.

I noticed the color issue on a very small scale with the K-x before I bought it, and saw that different RAW software could reduce or avoid it. However I've never seen an area as large as that.

Since you say it's not in the RAW, I would speculate that it has to do with either the camera's white balance shift process or chroma correction process. I'd say this is something that needs to be fixed...you should send that image to Pentax.
02-01-2010, 05:47 AM   #10
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QuoteOriginally posted by Graystar Quote
I like your exposure...the snow is nicely white.

I noticed the color issue on a very small scale with the K-x before I bought it, and saw that different RAW software could reduce or avoid it. However I've never seen an area as large as that.

Since you say it's not in the RAW, I would speculate that it has to do with either the camera's white balance shift process or chroma correction process. I'd say this is something that needs to be fixed...you should send that image to Pentax.
Thank you for the compliment. My camera is K200D, what I meant is jpeg algorithms can play tricks like this in any camera like Moire issue in the OP, IMO there is nothing to report, I was pushing severe light angles like extreme counter-sun situations etc, this is only weird one, obviously light rays diffracted from the snow at the top of the hill which acted like a glass prism refracted the light, and jpeg engine is just enhanced those colors.

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02-01-2010, 06:11 AM   #11
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QuoteOriginally posted by cbaytan Quote
Thank you for the compliment. My camera is K200D, what I meant is jpeg algorithms can play tricks like this in any camera like Moire issue in the OP, IMO there is nothing to report, I was pushing severe light angles like extreme counter-sun situations etc, this is only weird one, obviously light rays diffracted from the snow at the top of the hill which acted like a glass prism refracted the light, and jpeg engine is just enhanced those colors.
Ah...I thought it was a K-x.

I don't think this has anything to do with the JPEG engine. I see a lot of misunderstanding about JPEG...JPEG gets blamed for many things that are not its fault. JPEG is a storage format for images...not an image format. So an image isn't a JPEG until it's actually put away on the flash card or hard drive. Until then, it's a simple bit-mapped image. And when a JPEG is decompressed and loaded into editing software, it's once again a simple bit-mapped image. It won't be a JPEG again until it's saved.

JPEG compression can cause artifacts to appear. Artifacts relating to color usually cause color to be muted. In my study of JPEG artifacts I've never come across anything like your pink shift. So personally, I'm convinced the issue is the camera's processing of the image, and not JPEG compression.
02-01-2010, 10:35 AM   #12
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I had the same kind of moire on several videos I shot in the open sunlight.
My guess it that the UV filter which came with my camera causes it.
I forgot to take it of when filming candlelights and noticed two lights at a certain angle to the candle. The light mirrors from the lens onto the filter and back. Since I believe the filter is polarized this could somehow cancel out some light frequencies.

See my video of Taipei 101. Not the best shot though in many ways.

[yt]http://www.youtube.com/watch?v=c8RlO5PIQ-w[/yt]
02-01-2010, 12:56 PM   #13
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Moire appears even in high end video. Norm Abrams plaid shirts always give a moire. As do picket fences or pretty much anything with straight lines at the correct (actually incorrect) angle to the sensor grid. So it's not just your camera.
02-01-2010, 01:00 PM   #14
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Moire in video is much more common since it is not filtered.
Just an unfortunate way of how the pixels are chosen to be part of the 1280x720 video image.
If Pentax could implement downsampling to 1280x720 by using pixel binning or other techniques these artefacts would surely dissapear. Generally the 1280x720 format is implemented on the CMOS sensor by a special read-out function which skips horizontal pixels and whole lines. It seems that reading the entire CMOS at 24 fps is still not yet possible.
Camera manufacturer Red inc. has the RED One and several CMOS sensors varying from wide APS-C, FF to realy large format that can do beyond 30 fps full frame. Which comes at quite a cost of course. No doubt this technology will become cheaper over the years but don't hold your breath while waiting ;-)

Regards,
Jan Rinze.
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