Tuesday, December 09, 2008

Unshielded Bodies?

Here is a detailed article by Peter Zheng about the internal dissections and PCB layouts of different DSLR models of different brands, namely, Pentax, Canon and Nikon ones:-

http://docs.google.com/View?docid=df2k6qz2_89db3xzcdq

In the beginning of his article, an excerpt of a Japanese interview with the Pentax imaging department, about the concern of EMI (Electro-Magnetic Interference) of the Pentax DSLR bodies, is also quoted.

One important thing was found and is noted: Pentax's internal circuitries and PCBs (Printed Circuit Boards, and of course those electronic components inclusive) are NOT shielded *whilst* all other models made by Canon and Nikon are well shielded, grade and price regardless. In fact, this could cause EMI issues, also as admitted by the Pentax official in the interview.

The author further writes that Pentax DSLR bodies, from *ist Ds to K10D, are all unshielded. Although he writes no further information about if the K20D, K200D and K-m are shielded, it would be fairly reasonable and safer to assume that they are also unshielded. Nonetheless, it still has the (minimal) chance that Pentax would have already improved the design, by adding a metallic shield like the other DSLR makers have been doing (since long ago), but none of us is for sure unless there is anyone who has dissected one of the three newer Pentax bodies and let us know.

According to the IEC standards, the formal term used on describing devices and appliances should not interfere with each others, electro-magnetically, is called the "Electro-Magnetic Compatibility", or just called EMC in short-form. And, EMC compliance is validated only if one of the following two conditions are fulfilled:-

1. The device does not interfere with any other devices nearby;

2. Any EMI existent in the environment which the device is placed, should not interfere and affect the normal operations of the device.

There is a third case which is not mentioned in the IEC standards, though (but indeed it is not needed to be mentioned, but it is crucial!), that is, the device should not interfere itself and the inside electronic components of the device should not interfere each others amongst themselves. In fact, this is just something that is closely associated with the PCB and component layout design. And of course, the PCB metal shield (as shown in other C and N DSLR models) should help, and in most cases, as it helps to suppress EMI from "flying" around inside the body, once those are arisen, and could eventually be picked up by the PCB traces and/or other electronic components. As for the Pentax cases, you can see some examples of strange interferences which could affect the final images here and here (cases of the K10D and K20D respectively).

Now, let's look at the operating frequencies of a typical 10MP DSLR, say, with the most "popular" Sony 10MP CCD imager. First of all, the CCD is operating at a clock frequency of 25MHz, for the pixel signals to be "clocked" out in a chain (of waveform). Secondly, the CPU and IPU and internal memory RAM etc. of the camera are operating at much high frequencies, usually from several hundreds of MHz to a few GHz nowadays (the lower GHz range is well known as Microwave in dailylife term). For the former 25MHz signals, any external EMI at that *base* frequency could severely affect the signal. However, EMIs with higher frequencies could also affect the signal waveform as the 25MHz is only the base frequencies and there exists higher harmonics (in multiples of the base frequency) contained in the actual signal to be transmitted (which is generated out from the CCD imager, and to be received for second stage processing). As a result, the final transmitted/received signal is distorted (in addition to signal loss and other imperfection of the electronics and circuitries), which eventually to appear as noise, and even worse, in bandings or pattern noises. Similarly, the same case applies to the CPU and IPU which are operating at the GHz levels. The only difference is that the CCD signal (same case for CMOS as well) are just primitive analogue devices which are even be more susceptible to those EMIs and especially they are the heart of the DSLRs as the imagers are just for receiving the raw image and light data afterall.

Well, still remember the IEC EMC standards and the two prime and essential requirements? The other concern is how an (electronics) device which is EM compatible should NOT interfere with other appliances. In the above case, the DSLRs with the (most popular and common) Sony CCD imager could affect FM radio and other RC controlled devices or communication systems in range of tens of MHz or higher (in multiples of that base frequency, even worse, if mixed with other EMIs with other frequencies, in the new intermodulated frequencies as well). And, the much higher CPU and IPU EMIs could affect other devices which are operating at GHz frequencies, e.g., mobile phones, indoor DECT phones, PC and notebooks and so on.

So, afterall, why not shieldED the PCBs?? Even Canon and Nikon DSLRs that are having a metal outer body shells are shielded. How come Pentax DSLRs with only metal INNER frames but all plastic outer shells are NOT be shielded??? Well, I must agree this is a huge concern and issue as raised.

13 Comments:

Anonymous said...

Pretty sure Pentax is well aware of EMF and it's effects:
Pentax Team (by Mr. T. Hotta who was in charge of firmware design): Indeed. Recent Cbs might look at one piece, but there are actually layers to this and a slight change in wiring alone significantly changes how noise appears. In a digicam, DDR2 memory that functions at a very high frequency and many other parts all produce radio waves.
http://www.ok1000pentax.com/2006/12/k10d-interview-with-engineers-of-pentax.html
AND the camera is sheilded. Your blog implies no sheilding but if you look at this picture you will see that is not true:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=30181367
K10 IS is shielded. Look at all the metal on the back cover...

RiceHigh said...

Quoting what a firmware programmer said about RF engineering is something that is really interesting and somewhat funny.

Thanks for your remark about the metal on the back cover. Yes, I agree that it is a shield, but it is not a complete one. There is a large window opened for the back LCD. Nor, the shield is covering the PCB closely and solely. When there is a big hole in the shield, the effectiveness of the shielding is in doubt. Just think about if a hole exists in a waterproof sealing.. And actually just a very small one will cause complete failure.

Well, btw, isn't that Peter Zheng have already responded to you previously and exactly:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=30184866

http://forums.dpreview.com/forums/read.asp?forum=1036&message=30185088

Anonymous said...

Point was Pentax was obviously aware of the effects of RF on an image.
And gordonBGood responded to Peters comments as well. He said that there was no evidence of any RF influences. Neither Peter or you have any proof except by inference that Pentax has any RF problems beside the known one w/ the grip. seems even a minor oversite produces devastating results. Of course when the aliens crank up their intergalactic transmitter Pentax cameras may stop working while nikon and Canons are still happily shooting the spaceships ;)
SHOW me proof of global RF problems and I'll believe both you and him. to be honest he seems just like another chicken little saying the sky is falling. Everything he said was conjecture based on assumptions and circumstantial evidence...

Anonymous said...

AGAIN I say why don't you correct your blog to show that Pentax DOES have some shielding though you BELIEVE (with NO facts or I assume practical experience) it is inadequate.......
I guess that is just an inconvenient truth as is so often the case with you.

RiceHigh said...

Did Chicken Little tell the truth? Although no people believed him, not until when they finally saw "the Sky is falling" themselves!

PeterZheng said...

Hi RiceHigh!

I am very happy to see your text "Unshielded Bodies?".

(I'm sorry for my own English is poor).

let me tells everyone, Pentax has replied to me.

When I sent :"Thank you for your mail. but I want to say:
I sincerely hope that the Pentax K30D design group would see my feedback with these texts and to consider it".

Pentax 2nd replied to me:
"We surely did".

Perhaps someone disliked seeing that PENTAX will be a progress in future?

Anonymous said...(in here ago)
"And gordonBGood responded to Peters comments as well. He said that there was no evidence of any RF influences. Neither Peter or you have any proof except by inference that Pentax has any RF problems beside the known one w/ the grip. seems even a minor oversite produces devastating results. Of course when the aliens crank up their intergalactic transmitter Pentax cameras may stop working while nikon and Canons are still happily shooting the spaceships".

Please looking here:
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=30166992&page=2

http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=30166992&page=3

Very regrettable, I knew that EMR stripe, and in there him did not use a battery grip. The DPR testing's Elizabeth head image also does not with a battery grip, that D-BG2 grip was delayed 3 months at least.

We have known that the K10d/K20d is easier susceptible interfering from the external EMR in the daily EM environment (merely ISO800) than other DSLR, its nearby did not large RF antenna, no radar, and D-BG2 does not accessional.

look this photo:
http://lh5.ggpht.com/_cs3o43xCXno/STiUZuKCUyI/AAAAAAAAA5c/v1Ld7HMSaLA/s800/k20D_IMGP1822-1.jpg

Also, the D-BG2 problem is more obvious, it looks like the battery grip's problem, but in fact it has also included another problem, K10d lacked of the metallic shield craft. (Despite the grip or camera correlative portion's design should also be improvement).

Merry Christmas!
PeterZheng

PeterZheng said...

My google documents has updated (text and picture),

** Ask for Pentax DSLR internal craft improvement (II) is herer:
http://docs.google.com/Doc?id=df2k6qz2_89db3xzcdq
or
http://docs.google.com/View?docid=df2k6qz2_89db3xzcdq

* Ask for Pentax DSLR internal craft improvement (I):
http://docs.google.com/Doc?id=df2k6qz2_10c2wnq2fm
or
http://docs.google.com/View?docid=df2k6qz2_10c2wnq2fm

***** The PCB wiring design comparison *****
Please pay attention to Canon, Nikon PCB, which their PCB wiring design would be advantageous to EMI reduces, its PCB surface layer did not many-crowded wiring as the signal circuitry.

However, the K10D PCB surface layer was many-crowded wiring, it looks like a computer PCB and not a camera PCB, such that PCB wiring is a bad way to as the camera PCB.

Thus k10d much more of need to take the metallic shield craft than other DSLR cameras, but it had not.

***** Electronic craft artistry *****
You would see them each picture, k10d PCB is full of messy cables and plaster, and it looks like a student' s experiment and not a product, and which would obviously block the production line of productive efficiency, that is Japanese electronical product levels? It should be improved.
_______________________________
I have seen that Canon has been a strong power in electronic technology:
http://www.canon-compo.co.jp/e/work/denshi.html
http://www.canon-compo.co.jp/e/work/denshi3.html
http://www.canon-compo.co.jp/technology/electric.html
http://www.canon-machinery.co.jp/products/index.html
http://www.canon-machinery.co.jp/products/kiban/index.html

Then we must surrender to Canon? :-(
PeterZheng

Anonymous said...

Well Peter, nice to see you and RH together.
Personally Peter you need more than what you are presenting. Or have RH re-translate so it is in more of an understandable form. I still see no proof besides your own beliefs. Maybe you can get some 3rd party to verify it.....
Other than that I suggest, until Pentax meets both you and RH's expectations, that you sell everthing Pentax and play happpily with Canon...

Happy holidays...

PeterZheng said...

an Anonymous said:
"that you sell everthing Pentax and play happpily with Canon".

Ho-Ho, which because I had criticized that the K10D some flaws?

Anonymous said:
"I still see no proof besides your own beliefs. Maybe you can get some 3rd party to verify it....."

You wants that let me also similarly say: "I have not seen any questions" and "Pentax good to good"?

Anonymous said:
"Or have RH re-translate so it is in more of an understandable form".

Yes, my own English is poor, then you merely need "an understandable" of best English and not your techno-background problem, such your "everthing" and " happpily" ...:-)

RiceHigh said...

Peter, just ignore that fanboy. It's totally useless and meaningless to respond to him and you'll just end up with wasting your valuable time to do so.

I appreciate much your efforts to show us those valuable information and useful comparisons. The quick facts are that the PCB layout and PCB shielding of Pentax DSLR are inferior than those of Canon and Nikon DSLRs.

It's totally for sure that there are rooms for improvement for both above and Pentax do need to spend more efforts and pay more attentions so as to upkeep in the game.

From your shown photos, it could also be noted that In addition to the very crowded surface PCB with many traces on it, there is one thing that is even worse: That is, there are many jumper wires on the PCB board which are "flying" around, which is the most undesirable thing in the design of any electronics circuit boards, which just tells that many design modifications on the circuit were made after the PCB was designed and mass fabricated. Such a rough design and rush production just means unmatured products, which are most likely subject to more bugs and problems, of course.

Anonymous said...

No Peter, you are mistaken. And this presents an issue that both you and RH present.
Just because someone disagrees with you they are not a fanboy. Just because someone doesn't believe YOU, they are not a fanboy. Just because someone doesn't understand you they are not a fanboy.
Both you and RH use this term as a crutch when you really have nothing constructive to say, or worse, when someone presents evidence or beliefs contrary to your own.
Bottom line me and others have no problems with RFI or how the circuit board looks. For gosh sakes, do you disassemble and criticize every piece of electronics you buy??? Seems like a frivolous waste of time but it's yours to waste. On that matter, being a minor tinkerer I've seen "rats nest" electrical things work forever and efficiently while neat cookie cutter circuit boards fail by the buckets.Take motherboards for example ten of thousands (or millions) of really pretty circuit designs failing in 2-3 years due to electrolytic caps. Do the cameras take pleasing pictures? Guess most people feel so.
As to the canon comment, only fools hang on to "things" that make them unhappy. No matter what you do or where you go with the camera you will always feel "something could go wrong look at the lack of shielding or, how sloppy the wiring is". So in all honesty why put up with it. It is ILLOGICAL at the least. Dump the stuff, move on and make yourself happy. I see no problem in it. You did your job, you said your peace now GET OVER IT.. there just toys ;)
I never said you were completely mistaken, I just want more evidence then you. Sorry if that offends you but I never ,ever , ever believe one person. I will admit some people are higher on my credibility scale. You are at neutral. RH of course is an extreme negative. That's my system and beliefs. Call me what you like but I believe in treating people fairly till they lose credibility...
now as to the spelling errors, if that is all you childishly need to pick on so be it. I thought you were better than that. Maybe "play happy w Canon" could be construed as a bit condescending but it is the truth....

Anonymous said...

And Peter, why don't you ask RH what KIND of an engineer he is.(if in fact that is what he is) Seems to be a world class secret.... ;)

Anonymous said...

Well the photos look pretty convincing to me, and I've heard some complaints about Pentax hardware quality, so it really makes me wonder...
Thankyou for this information anyways.

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