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12-16-2008, 10:50 AM   #61
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It's something that happens in bursts - I'll have 30 or 40 shots with no problem and then 3 in the next 10 will be like this. Not the SD card, not the iso (happens on low isos and with slected iso as well as auto iso). Happens in 2s mirror lock, standard shutter and 10s delay. I saw one or two examples of it in the first 1000 shots and it's been more regular since then.

I've seen it in shots where the camera has been indoors for a few hours and the internal temp is showing 16 degrees.

QuoteOriginally posted by pentaxmz Quote

Does the banding appear all the time or in specific conditions. I have only taken about 20 photos thus far and I have not encountered the banding yet.

What do I have to do to encourage the banding problem to appear (if it exists in my camera)?

This is very preliminary but it seems as though the problem may not be due to a specific production run or older components.

Perhaps the issue:
- component(s) prone to failure (and I'm not affected because I haven't
taken enough photos yet) or or simply a random failure (some do/will,
some do not/will not).

Did the K20D ALWAYS exhibit this problem or did it appear eventually?

My picture count is about: 300 (this info is in the EXIF) what is yours?

- component(s) are temperature sensitive. I think Phillip suggested this is not
the case. What is the temperature recorded for the photos that exhibit this
problem? The lowest internal temperature in my photos, thus far, is 15 c.

- component(s) exhibit a failure only during specific settings. My first test photos
were all taken in Av mode at all ISOs. Perhaps I should take other settings?
What are the specific settings used when you see this problem?

Anything else?


12-16-2008, 12:49 PM   #62
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QuoteOriginally posted by Cuchulainn Quote
It's something that happens in bursts - I'll have 30 or 40 shots with no problem and then 3 in the next 10 will be like this. Not the SD card, not the iso (happens on low isos and with slected iso as well as auto iso). Happens in 2s mirror lock, standard shutter and 10s delay. I saw one or two examples of it in the first 1000 shots and it's been more regular since then.

I've seen it in shots where the camera has been indoors for a few hours and the internal temp is showing 16 degrees.
Thanks for the information.

What is your camera image count? Was this problem evident from the first photos or did it begin appearing later?
12-16-2008, 12:54 PM   #63
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QuoteOriginally posted by jeffkrol Quote
Not quite sure that this applies. If it's just a rounding error caused by a clock very little detail if any will be lost due to recalculating the correct values. From the Silkypics example not only is it apparently easily corrected, detail does not seem to be smeared as in other forms of NR. Just a minor visible observation. Again, it shouldn't be there but it is much more handlable then the k10 VPN, which was way more random and hard to deal with without destroying some detail
I suspected that as well, however, Phillip's first argument is definitely valid. Why should a K20D owner have to deal with this extra step of image correction. It is reasonable to expect all images captured by the K20D are in within the stated specifications.

This is unacceptable, especially to those who make a living with this camera (time = money!).

Unfortunately, I did not buy an extended warranty because I figured that the K20 would last many years. Hmmm, I hope this wasn't a mistake.
12-16-2008, 12:56 PM   #64
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QuoteOriginally posted by Cuchulainn Quote
It's something that happens in bursts - I'll have 30 or 40 shots with no problem and then 3 in the next 10 will be like this. Not the SD card, not the iso (happens on low isos and with slected iso as well as auto iso). Happens in 2s mirror lock, standard shutter and 10s delay. I saw one or two examples of it in the first 1000 shots and it's been more regular since then.

I've seen it in shots where the camera has been indoors for a few hours and the internal temp is showing 16 degrees.
What about RAW or JPG? Does it matter? If it is JPG, does it matter what settings are used?

BTW, How the heck do I get the camera to save in JPG and RAW simultaneously? It seems to be one or the other but not both. I thought this was possible.

12-16-2008, 02:13 PM   #65
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RAW or jpeg, the problem takes its sources when reading the sensor, so it is there in raw. however the jpeg compression can affect more or less the effect (smooth it out somewhat).


@pentaxmz : you can set saving parameters it in the menu REC
i think its the config menu that it lets you parametrize the raw button so it saves to jpeg as well
12-16-2008, 02:51 PM   #66
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QuoteOriginally posted by pentaxmz Quote
Wow, that concerns me because my camera is just a little bit older than yours.

Does the banding appear all the time or in specific conditions. I have only taken about 20 photos thus far and I have not encountered the banding yet.

What do I have to do to encourage the banding problem to appear (if it exists in my camera)?
banding appears in all sorts of conditions. however it is not always explicit as some shots reveal. but you can certainly encourage the banding by taking shots of say a uniform background in low light
you might not get clear visible whitened stripes (that's the worst case)
but you will get something like what dpreview obtained in their review.
doing an fft on these shots clearly reveals the same signal present in the image, though at a lower power.

QuoteOriginally posted by pentaxmz Quote
This is very preliminary but it seems as though the problem may not be due to a specific production run or older components.
on the dpreview thread, there is a report from a camera produced in march. that's the latest i've seen.
but we don't have that many bad reports yet, perhaps 10 people manifested themselves on the two threads. so, no can't say its a whole batch of camera affected (and hopefully too)

QuoteOriginally posted by pentaxmz Quote
Perhaps the issue:
- component(s) prone to failure (and I'm not affected because I haven't
taken enough photos yet) or or simply a random failure (some do/will,
some do not/will not).

Did the K20D ALWAYS exhibit this problem or did it appear eventually?

My picture count is about: 300 (this info is in the EXIF) what is yours?

- component(s) are temperature sensitive. I think Phillip suggested this is not
the case. What is the temperature recorded for the photos that exhibit this
problem? The lowest internal temperature in my photos, thus far, is 15 c.

- component(s) exhibit a failure only during specific settings. My first test photos
were all taken in Av mode at all ISOs. Perhaps I should take other settings?
What are the specific settings used when you see this problem?

Anything else?
well my camera did it quite early after i bought it in march. but then didnt do it for the whole summer, thought i've had banding in noise for lowlight, more than the camera is supposed to show.

i've done quite a lot of shots. and recently it's like it's more prone to doing this banding. but it's been ok for say 4000 shots...
i just don't want the problem to get worse and worse especially after the garanty ends. so i want to get the problem sorted out

temperature: i didnt want to say components are not prone to temperature
actually the higher the temperature the more thermal noise that can affect the AD. that's why sensors are cooled in astronomy.
but why is this interfering signal appearing more often in cold weather
well just hypotheses, but if it is the clock signal that interferes in the A/D conversion than, temperature change might affect a bad electronic component so that when the clock signal is high, it interferes and whitens the pixel and when it is low it is not affected, since the sensor is read in parallel, i presume on the horizontal axis, the conversion leads to stripes. that just a hypothesis. but as an engineer in signal processing, it would make sense.

the highest temperature from the camera exif data on an image that has the problem in its extreme case, was 9c in my case. but at 25 i get the banding in noise quite clearly. but i also have plenty of good pics at -15
and also quite a lote at 0 -5, with good light, nice sunshine, and horrible banding. some have repported banding at much higer temps

i've had the problem in all kinds of settings, AV auto, M, iso 100 to 800 with at least 4 different lenses (including old m42 ones with no electronics)

my seller just gave a cd full of bad pics to a pentax sales rep. and i should get some news soon. i'll post back.

the question that remains for me is, is pentax aware some of its k20 are subject to the problem, do they know how frequent it is? . we've had perhaps less then 10 persons reporting the problem yet (on two threads including dpreview's thread on the subject). but that doesn't tell us how many people have the problem and are not reporting it on forums.

anyways, i don't think the problem is really bad (in that it does not affects all camera). i do think the camera has to be changed. i don't know how pentax is cooperating on the subject. some had to sent the camera back 3 times before they had it changed...
i'm still waiting for an answer from pentax.. and i need a camera for the holidays as you all do, don't you?

thanks everyone for your concern about the subject. this certainly will give some support for the affected cameras to be changed by pentax.

sincerely.

P
12-16-2008, 03:13 PM   #67
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The only answer

With regard to the original post (I haven't read all the replies here and cannot believe that this simple and obvious case is discussed at all).

The only correct answer is:

A K20D randomly producing images with 2- or 4-pixel wide banding is defective and MUST be replaced by Pentax.

This is a known defect.

There are quite some reports around the web (about 3 or so in pentaxforums.com).

The defect has been reported at very high as well as very low temperatures. So, it may be temperature-independent. It is rare and hard to reproduce.

The SD-card (or reader) has NOTHING to do with it. And obviously so: JPG is a compressed format and therefore, card errors for mathematical reasons, cannot produce a regular banding artifact.


To the OP:
Insist to get a replacement body by all means. To the best of my knowledge, it hasn't been repaired yet -- Pentax always replaced the entire body. Involve a laywer if the dealer refuses to cooperate. The entire case is obvious.

Last edited by falconeye; 12-16-2008 at 03:21 PM.
12-16-2008, 05:01 PM   #68
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QuoteOriginally posted by pentaxmz Quote

I took photos of the same image at every available ISO (I omitted 100 ISO because there was too much shake (1/8 sec exposure).

I also noted the camera's internal temperature in each photo never went below +15 degrees Celsius; that is despite it being about -12 c. I wasn't outside long enough but I promise to give the camera a real workout this weekend.
nothing can be seen on the shots, though. perhaps they are in quite good light conditions. the banding, in my cameras appears quite always in low light conditions . however, your samples are a bit small to analyse, best is to use 512x512 crops and do an fft on it.

thanks

12-20-2008, 08:50 PM   #69
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hi there,

just posting back on the latest information
and to date, my seller has not received the expected cooperation from either the technicians and respective responsible (somewhere in ontario, canada) or from the sales rep for quebec...
i'm going backcountry skiing tomorrow for a couple of days, and will bring my k20...
ah well. still hope to get good news tuesday...
12-22-2008, 05:34 AM   #70
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My K20D has a vertical banding issue too. At any ISO especially with DR on and becoming more noticeble as ISO get higher until 800 when NR kicks in, and again with worsening banding above that.

I mainly notice it in under-exposed areas in the green channel, and is amplified when I try to drag details out from shadows. But as I learnt to correctly expose I notice this less often. Now it doesn't bother me much and I just enjoy taking beautiful correctly exposed pictures with this camera.
12-27-2008, 07:21 AM   #71
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I've got this problem on my K20D too. Manufacture was March 2008 so it looks as if there is a problem with a large range of manufacturing dates. I'm up to around 3000 shots at the moment, and I first noticed this at around 2000 shots in October.
Few things looking back through my files:
It appears to be completely random. Like others I thought it was temperature, card, battery, etc. All these may contribute to the problem, but I don't think that they are the main cause.
On my camera it appears to be very rare that the whole image is affected. Most examples the banding is in the shadow only, and more noticeable when you try to pull detail out. Also, and as noted by others nearly all the examples I can find are either high contrast or underexposed.

Spoke to the dealer I bought it from this morning here in the UK. Very pleasant people, but no tech support there today. Will phone again Monday, but the opinion was that they would send it back to Pentax for examination.
My thinking on this is that because Pentax won't accept there is a problem, then with all due respect to the dealer, am I going to start this the "Send it back / weeks of waiting / no problem found / send it back" cycle which means not having the camera for weeks, if not months?
Being as the relatively few images affected are mostly unusable for my purposes anyway due to underexposure etc, am I better off being more careful with my exposure (and yes I know I should be anyway! ) thus hopefully not getting the problem to any great degree, and not having the hassle of sending it back?
I think that this problem is probably a lot more widespread than has been reported. Unless you actually look at the images quite critically at 100% it's not really apparent, so many users may not have noticed anything at all.
12-27-2008, 10:51 AM   #72
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QuoteOriginally posted by DWPhoto Quote
I think that this problem is probably a lot more widespread than has been reported.
It is widespread enough that a clear failure description is available (at least, on the internet).

I cannot add anything to what I said except to repeat: Get a lawyer's assistence because the bug will never reproducible. Pentax MUST learn to accept sample photos (which failed) alongside the camera sent back to them.
12-28-2008, 12:00 AM   #73
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I shoot in very cold winter weather a lot with my K20D and have had it chilled to ambient -24C at the coldest. Still performed like a champ.
01-03-2009, 04:52 PM   #74
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I've got this problem too with my K20D. The first time I saw this was at about 10 deg. F in 1 of about 30-40 photos taken that day. A few days later at about the same temps, none showed on about 80-90 photos.
I have a few with some vertical stripes taken a few days ago at about -5 deg. F but they were showing up on photos when both the batteries in the body and grip were getting low.
I don't know when my K20D was manufactured, if anybody knows a Mac program that shows the manufactured date I'll post it.
I don't know if I can get this fixed, if i can be, under warranty since I didn't get a copy of the sales receipt from the original owner.
01-04-2009, 02:37 PM   #75
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and some horizontal too....

Tomorrow i will send my K20D back for repair.

I didn't read the whole thread but i understand some of you want to know it is possible to reproduce it. With my camera i can for almost 70%-80%. (B)ulb-setting. Exposure > 60-70 secs. It appears in- and outdoors with different memorycards, different lenses, different ISO's, etc. So for me it's not a temperature-issue.



Here you can find the rest of my problems :Banding - a set on Flickr

In normal conditions i have vertical banding with every 4-5 out of 200 photos.


From PhotoMe: Pentax Model: K20D, Manufacture date: 2008-04-03, Production ID: 1, Internal Serial number: 11172

Last edited by rverhag; 01-04-2009 at 03:52 PM.
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