Some K-5s have stains on sensor/AA filter (Part II)

Started Dec 5, 2010 | Discussions
Britney Elvis Veteran Member • Posts: 5,256
Calling John C Pentax and Ned B

We here in the USA would love to have you investigate this and "get back to us".

You are always very quick to post when Pentax has something new to sell.

Psst... Still waiting for you all to get back to us on the SDM issues with the DA* zooms, and more importantly for me --- The KX blur issue.

But I realize you need to hop this K5 issue first, since this it will become a PR / forum nightmare for you. All those pics of lines of dots in the center of the images from what otherwise seems to be a great camera.

I hope for us (loyal pentaxians) it is a fluke of the early manufacturing process, and that you are open and honest about it rather than the usual ignore/deny/dodge and run...

Gus
K100d - K20 - Kx

-- hide signature --

Help me Mr Wizard ----- "Drizzle, drazzle, druzzle, drome; time for zis one to come home."

spqr_ca
spqr_ca Contributing Member • Posts: 707
Re: I probably have it, but...

I'll be curious to hear your report on this, in any case. I already replaced one K-5 for the rear e-dial, so I'm reluctant to go through that again, especially since I haven't seen anything strange in close to a 1000 shots since.

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RPulley Senior Member • Posts: 1,175
Re: Some K-5s have stains on sensor/AA filter (Part II)

Pete Fang wrote:

I started this thread a day ago:

http://forums.dpreview.com/forums/read.asp?forum=1036&message=37092371

It has reached the maximum number of posts (150) within 22 hours. Therefore, I am starting this new threads so we can continue the discussion here.

Peter

As I reported in the other thread, my K5 has a small area, maybe the smallest and faintest I have seen in the examples, but it is definitely there.

I have already setup a return to Amazon, and ordered another, which will be delivered Tuesday.

It will be interesting to report if this next camera has the same issue.

Since I suspect some sort of process problem in the assembly of the camera that is leaving dirt or residue on the sensor or the AA filter, getting a good one could be hit or miss unless Pentax has figured out the root cause and already corrected the problem.

If the issue is some sort of sensor issue as delivered from Sony it may be that the problem is with a certain batch of sensors, but I guess that at the end of the day, I do not care as long as I can return it and get a good one.

Frankly, I am more concerned about getting the flash exposure sorted out soon.

Ray

Dcuk Contributing Member • Posts: 877
Re: Some K-5s have stains on sensor/AA filter (Part II)

Hi Peter,

Just before I send my camera back, I thought it might be helpful if I took some photographs (using my Raynox M-250) , so people can see what they are looking for and don't mistake dust as a problem. Plus so I have images to send as evidence with the camera.

I can definitely say, from the images I just captured, that the marks are on the underside of the AA filter .

First:

Focus on surface of the AA filter (compare the left side of the photo for the plane of focus) the normal dust can be seen in focus, while marks on the underside (arrow pointing to them) are out of focus.

Click images once or twice for full size preview

Next:

Focus on underside of the AA filter (compare the left side of the photo for the plane of focus) normal dust is now out of focus, while marks on the underside (arrow pointing to them) are in focus.

Click images once or twice for full size preview

Lastly:

Moving the light to a better location shows all the marks on the underside of the AA filter more clearly.
Here is a 100% crop.

Please note the fine white marks are the problem area, the bubble effect seen below the marks, is out of focus reflections from the light.

How the marks look in a small aperture photograph (remember photographs are captured upside down by the sensor)

.

Do hope these photographs will help others know what they are looking for (can also be seen with the naked eye) so people don't think normal dust specks are the problem.

Best wishes,

Dcuk

Britney Elvis Veteran Member • Posts: 5,256
Raynox 250 as an investigative tool...

Thank you for the effort.

I am very impressed with your raynox skills... Well done. THis is one time where the shallow depth of field of the raynox really pays off.

Good luck with your return.

Hopefully this will put to bed all of the "maybe its dust" "did you try and clean it"

What would worry me more are the folks who say... "I dont shoot above F8 so it does not bother me. If for what ever reason it is some kind of contamination, there is no guarantee it would not get worse over time.

Dcuk wrote:
Hi Peter,

Just before I send my camera back, I thought it might be helpful if I took some photographs (using my Raynox M-250) , so people can see what they are looking for and don't mistake dust as a problem. Plus so I have images to send as evidence with the camera.

I can definitely say, from the images I just captured, that the marks are on the underside of the AA filter .

First:

Focus on surface of the AA filter (compare the left side of the photo for the plane of focus) the normal dust can be seen in focus, while marks on the underside (arrow pointing to them) are out of focus.

Click images once or twice for full size preview

Next:

Focus on underside of the AA filter (compare the left side of the photo for the plane of focus) normal dust is now out of focus, while marks on the underside (arrow pointing to them) are in focus.

Click images once or twice for full size preview

Lastly:

Moving the light to a better location shows all the marks on the underside of the AA filter more clearly.
Here is a 100% crop.

Please note the fine white marks are the problem area, the bubble effect seen below the marks, is out of focus reflections from the light.

How the marks look in a small aperture photograph (remember photographs are captured upside down by the sensor)

.

Do hope these photographs will help others know what they are looking for (can also be seen with the naked eye) so people don't think normal dust specks are the problem.

Best wishes,

Dcuk

-- hide signature --

'Nothing is worse than active ignorance'

Johann Wolfgang von Goethe

awaldram
awaldram Forum Pro • Posts: 13,263
Re: Raynox 250 as an investigative tool...

I'm guessing its a manufacturing defect in the aa filter itself.

Looks like mine has it to lesser degree

100% crop lower quadrant this is a 15 second exposure deliberately moved around the target to ensure not target related, checked 3 lens and re-mapped pixels twice.

I'm not overly concerned and will await developments.

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falconeyes
falconeyes Senior Member • Posts: 1,602
Some own analysis (Stainology)

Dcuk wrote:

Focus on underside of the AA filter (compare the left side of the photo for the plane of focus) normal dust is now out of focus, while marks on the underside (arrow pointing to them) are in focus.

Dcuk,

thanks for your work.

I've come to similiar conclusions using another approch.

You can read it here:

http://bit.ly/hRAqyN

The only difference is that I identify the source on the upper (outside) of the cmos chip cover glass rather than the bottom surface of the AA filter.

There is a small gap in between, maybe 0.2mm.

Best regards,
Falk

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spqr_ca
spqr_ca Contributing Member • Posts: 707
Okay, I peeked

MightyMike wrote:

I wouldn't mind however knowing if you've got an issue or not, but its your choice to test.

Not a hint of it, heck not even a hint of dust either. In that sense, I do feel better knowing, but having taken quite a few shots, I never detected a problem with it anyways so it wasn't really an issue for me.

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chris gunn
chris gunn Veteran Member • Posts: 8,723
Top Post! Excellent investigation Dcuk :)

Dcuk wrote:

Just before I send my camera back, I thought it might be helpful if I took some photographs (using my Raynox M-250) , so people can see what they are looking for and don't mistake dust as a problem. Plus so I have images to send as evidence with the camera.

I can definitely say, from the images I just captured, that the marks are on the underside of the AA filter .

Interesting!

I've read people here suspect this is an AA filter problem, but now I wonder if it is an assembly problem.

Do hope these photographs will help others know what they are looking for (can also be seen with the naked eye) so people don't think normal dust specks are the problem.

Yes, it is easy to be confused

Thank you for your work!

-- hide signature --

cheers!

Gunn

-- Get a big lens and get closer™.

jthommo101 Contributing Member • Posts: 521
Dcuk's photos seen by Pentax

I've just spoken to a very helpful gentleman at CR Kennedy (the Australian Pentax distributor) who told me that they had become aware of the problem this morning and have alerted Pentax Japan to Dcuk's pictures.

The power of the internet.

I won't go into the detail of the conversation I had with the CRK chap because I did not ask him if I could publish it. It is fair to say, though, that defective cameras will be fixed under warranty.

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Gazooma Senior Member • Posts: 2,159
Re: Raynox 250 as an investigative tool...

Britney Elvis wrote:

Thank you for the effort.

Me to, thanks. Maybe it will help Pentax to see this problem, as they apparently can't see any problem. The Raynox thing must be nuclear like technology and not available to camera makers.

I am very impressed with your raynox skills... Well done. THis is one time where the shallow depth of field of the raynox really pays off.

Good luck with your return.

Hopefully this will put to bed all of the "maybe its dust" "did you try and clean it"

What would worry me more are the folks who say... "I dont shoot above F8 so it does not bother me.

Gus, you don't have to worry about those folks. They are very happy.

If for what ever reason it is some kind of contamination, there is no guarantee it would not get worse over time.

If they are like tiny drops of some material, then it is not impossible that they can discolour or change its properties like transparency or even contaminate the sensor cells nearby, or gather dust. Or, it might not do anything at all.

Has anyone heard whether these stains have been found on the Nikon D7000's sensor yet? that may help explaain some things. I have no idea but just some question:

Are these the same things causing their "hot spots" when shooting video?

Are theses sensors supplied by Sony with the AA filter attached?

and is it possible that there are different sensors after all from what Nikon gets?

spqr_ca
spqr_ca Contributing Member • Posts: 707
Re: Raynox 250 as an investigative tool...

Britney Elvis wrote:

Hopefully this will put to bed all of the "maybe its dust" "did you try and clean it"

Checking that is a reasonable step regardless. Dust on the sensor, lens rear element, etc. should be taken out of the equation, this is common sense.

What would worry me more are the folks who say... "I dont shoot above F8 so it does not bother me. If for what ever reason it is some kind of contamination, there is no guarantee it would not get worse over time.

No guarantee that it would either. I completely understand the sentiment expressed, I only checked mine because Mike asked and, happily, I appear to be problem free. Nevertheless, I wasn't bothered because I saw no evidence of an issue in my images and as long as that was the case, I wasn't prepared to stress about it. Besides, if it did become one, I'd expect Pentax to do the right thing which, from all accounts, they appear to be doing. I don't expect a recall, the problem appears not to be a systemic manufacturing fault, so if they're dealing with it case by case, cool.

Frankly, I find the panic about this to be over the top.

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ManuH
ManuH Veteran Member • Posts: 3,898
Re: Raynox 250 as an investigative tool...

spqr_ca wrote:

Frankly, I find the panic about this to be over the top.

Maybe because yours is not affected Unfortunately mine is. It's like a small group of little specs (dots surrounded by a lighter disc) right in the middle of the sensor. Clearly visible at f/22 and still faintly visible at f/11. I'm going to make this repaired under warranty after Christmas. It's not a big deal for normal shooting but for macro it will be. And in my case, they're fortunately in the middle. That's usually in the top parts of the image (sky) where dust is usually the most visible.

Richard Murdey
Richard Murdey Senior Member • Posts: 2,886
Sigh

Read the old thread. Not much to learn there.

If there are some particles or flaws in the sensor or, more likely, in or on the surfaces of the the AA filter, I'm sorry you guys. The manufacturing conditions should be such that no such flaws should be present.

However, consider the paranoia effect.

"OMG! Guys stop down to f/22 and check your images, there might be spots!"

(Pentax world do this and are shocked and appalled to see spots. OMG! World explodes.)

So please be extra careful to determine that this is not dust. Also resize the image to a reasonable size (2000 pixel baseline) to confirm that it would be big enough to be visible. We are dealing with 16MP sensor here. Remember that minute flaws will be that much more visible at 100% crop.

Someone might also want to crosscheck the test on a K-7 or a Nikon D7000, or whatever dSLR they have handy as a reference.

Oh, and re the suggestion that the AA filter should be cleaned with acetone , that some idiot posted on the previous thread.

Don't. Even. Think. About. It.

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spqr_ca
spqr_ca Contributing Member • Posts: 707
Re: Raynox 250 as an investigative tool...

ManuH wrote:

spqr_ca wrote:

Frankly, I find the panic about this to be over the top.

Maybe because yours is not affected

Well, I already had one manufacturing flaw in the K-5 with the rear e-dial. The camera was replaced without any fuss and within an hour I was shooting again. Given that experience, I just couldn't be all that worried about something else...

It's not a big deal for normal shooting but for macro it will be. And in my case, they're fortunately in the middle.

Don't get me wrong, I do understand why some will want a replacement. For me, even with macro, I don't usually go above f/9 anyways. What I found to be over the top was the sense of almost panic, but yet Pentax already seemed to be responding well to it. In the end, when there is a flaw in a purchase and the company fixes or replaces it, I simply replace and move on, happy with the company for doing the right thing. Mistakes happen, I'm not so flawless that I become intolerant of that in others.

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OP Pete Fang Senior Member • Posts: 1,900
Re: Dcuk's photos seen by Pentax

jthommo101 wrote:

I've just spoken to a very helpful gentleman at CR Kennedy (the Australian Pentax distributor) who told me that they had become aware of the problem this morning and have alerted Pentax Japan to Dcuk's pictures.

The power of the internet.

This is encouraging to know. My original intention of starting the thread here was to bring awareness to users and to find out how widespread the issue is. With many tech experts in the forum, we are thankful to have Dcuk's images as well as Falk's analysis within 36 hours of starting the thread. Whatever the cause is, this could help Pentax get to the bottom of this issue and fix it once and for all.

Yes this is the power of the Internet, when utilized properly, of course.

Peter

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Peter Fang - Pentax user for more than 25 years: K-5 / MZ-S / Z-1 / SFX / LX
My Online Gallery: http://petefang.smugmug.com/

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Plaszm New Member • Posts: 6
Re: Some K-5s have stains on sensor/AA filter (Part II)

Thanks Dcuk!What you did give the evidences for our reporters who found the stain issue.Those apologist or others should stop their words and face this problem directly.

I do think it will better for Pentax if we face the problem directly.Especially some distributors and Pentax Official response did not treat customs well.

I will transform your images to the thread of our Chinese forums which Peter metioned the links in his post.
Kind regards

Dcuk wrote:
Hi Peter,

Just before I send my camera back, I thought it might be helpful if I took some photographs (using my Raynox M-250) , so people can see what they are looking for and don't mistake dust as a problem. Plus so I have images to send as evidence with the camera.

I can definitely say, from the images I just captured, that the marks are on the underside of the AA filter .

First:

Focus on surface of the AA filter (compare the left side of the photo for the plane of focus) the normal dust can be seen in focus, while marks on the underside (arrow pointing to them) are out of focus.

Click images once or twice for full size preview

Next:

Focus on underside of the AA filter (compare the left side of the photo for the plane of focus) normal dust is now out of focus, while marks on the underside (arrow pointing to them) are in focus.

Click images once or twice for full size preview

Lastly:

Moving the light to a better location shows all the marks on the underside of the AA filter more clearly.
Here is a 100% crop.

Please note the fine white marks are the problem area, the bubble effect seen below the marks, is out of focus reflections from the light.

How the marks look in a small aperture photograph (remember photographs are captured upside down by the sensor)

.

Do hope these photographs will help others know what they are looking for (can also be seen with the naked eye) so people don't think normal dust specks are the problem.

Best wishes,

Dcuk

-- hide signature --

Plaszm

MightyMike Forum Pro • Posts: 39,132
Re: Okay, I peeked

Thanks, This pretty much proves its not a batch issues but a scattered problem
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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spqr_ca
spqr_ca Contributing Member • Posts: 707
Re: Okay, I peeked

MightyMike wrote:

Thanks, This pretty much proves its not a batch issues but a scattered problem

I figured as much anyways. There's enough human element in any production line to ensure a certain element of error in the outcome, so Pentax isn't going to be immune to this. Given my experience with the rear e-dial, I was already satisfied that if I did have an issue, it would be dealt with swiftly. That's all that matters.

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chris gunn
chris gunn Veteran Member • Posts: 8,723
Re: Some own analysis (Stainology)

falconeyes wrote:

Dcuk wrote:

Focus on underside of the AA filter (compare the left side of the photo for the plane of focus) normal dust is now out of focus, while marks on the underside (arrow pointing to them) are in focus.

Dcuk,

thanks for your work.

I've come to similiar conclusions using another approch.

You can read it here:

http://bit.ly/hRAqyN

The only difference is that I identify the source on the upper (outside) of the cmos chip cover glass rather than the bottom surface of the AA filter.

There is a small gap in between, maybe 0.2mm.

Gosh! You calculated the distance of the spot from the sensor!? (41, 43, 46 µm)
Using penumbra and umbra diameters.

What fun! I have no idea if your physics is right, but I can see you have an argument

Congrats.

-- hide signature --

cheers!

Gunn

-- Get a big lens and get closer™.

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