Wednesday, January 31, 2007

The Secrets of the K10D (Part 3 of 3) – The Brain: The IPU

The IPU (Image Processing Unit) used in the K10D has been a big secret since Pentax announced the K10D in September last year. The photos published officially by Pentax, in the K10D catalogue, Pentax’s official website for digital cameras and Dpreview.com are actually all the same one which shows nothing printed on the chip. Well, here “they” are:-
http://www.dpreview.com/reviews/PentaxK10D/Images/Features/prime.jpg
http://www.digital.pentax.co.jp/en/35mm/k10d/feature.html

As seen in the short descriptions about the PRIME in the 2nd URL above of the Pentax website for digital cameras, Pentax have actually talked nearly nothing about the features and specifications of their new IPU. It only tells that the IPU utilizes DDR2 RAM at a data transfer speed of 800MB/s (but the RAM is actually just the peripheral) and that it is built on a 90nm fabrication process.

While people had been comparing the specifications of the ADC (Analog to Digital Converter) and the IPU used in the K10D and guessed that they are the NuCore products, there was no further information which could actually *confirm* anything until Samsung revealed the secrets, finally, about one month ago, in their camera website about the GX-10 when the photos of the ADC and the IPU were first got exposed:-
http://www.samsungcamera.com/product/pro_view.asp?prol_uid=1923&cat_uid=62

It can be seen in one of the pictures in the above page that two NuCore NDX-2240 chips are being used as the ADC whereas it can be seen in the other picture that the IPU shows a “PENTAX” brand name marked on it with some codes and numbers but no ordinary people know anything about what those represent. Well, there is no “PRIME” printed on the chip anyway, see:-
http://manage.samsungcamera.com/upload/editor/200612/15_1_2006121218134791.gif

Anyway, now, it can be confirmed that the IPU is not probably the NuCore SiP-2290, which is the recommended IPU to pair with the NDX-2240 by NuCore.

So, now it seems the “PRIME” is just a pure marketing name which either refers to the IPU alone or collectively refers to the image processing hardware and software inside the K10D, as a whole. In contrast, Canon’s DIGIC is clearly the IPU chips of their DSLRs and DCs, of which the name “DIGIC” is printed on all of the Canon’s IPU chips, despite that it is also widely used for marketing purpose.

Nevertheless, in this article, I shall still try to give some technical talks about the role of an IPU and why a powerful IPU is crucial for a successful DSLR with good image quality, in a general sense, followed by my views on the issue of "soft jpegs" which was originated from Phil Askey's reviews on the *ist D, DS and K10D.

Okay, let’s first look at the NuCore SiP-2290 technical catalogue (again), for what an IPU is and what it can do:-
http://www.nucoretech.com/nu3/images/80_downloads/pb_sip2290.us.pdf

By looking at the functional block diagram on the page 2, the major essential functions of an IPU shall include: 1. those basic mathematical calculation functions for the mapping between different color models as well as; 2. for basic adjustment of parameters within each of those color models.

For example, for those color models they can be RGB (Red, Green, Blue), HIS (Hue, Intensity, Saturation), YC (Luminance and Chroma(nce), or called the S-Video in the videoland), YCrCb (which is similar to YC but the C is further divided into two “vectors” called Cr and Cb, i.e. the red and blue color (chroma) components; called (one of the) “Component Video” in the videoland) and etc. Actually, all those color models has their own value for use, from for the ease of data processing and manipulation to representation in real-life in practical sense, for the end-users.

Other functions of the NuCore IPU include data compression, SD card interface controller, CCD bad pixel re-mapping function (so that the dead pixels could be ruled out and the end user will never see them, the missed info is to be inserted by interpolated values from the neighbourhood) , analog video signal (format) conversion and so on. It's interesting to note that the NuCore IPU does provide a few useful and popular DC functions like the digital effect filter and the face detection algorithm.

Well, let's focus back on the core function of an IPU, i.e., image processing. In addition to that the IPU supports the conversion between color models, it may or may not support also for the adjustment of parameters’ values within each of the color models, which this task is generally referred as “processing” of the image. If the IPU does not have those image processng functions built-in, higher level software algorithms need to be embedded, in the firmware. To elaborate the “processing” a little bit more, it is just that raw numeric values, for each of the parameters, for every pixel are picked up and then the IPU (or the higher level algorithms) will have all these adjusted, by mathematical formulas and some logics behind, with the aim of achieving certain effects, and it will ultimately “re-insert” all the new values for each of the parameters per pixel into a temporary buffer for further processing or for storage, if it is the final product.

Practically, the high level algorithms are usually defined in the firmware for all those adjustments of the image aspects, like white balance, saturation, contrast and brightness adjustment and so on. The high level algorithms used by Pentax in the K10D are known to be the "SilkyPix", which is originally developed by the Ichikawa Soft Laboratory which marketed their RAW convertors with the name SilkyPix Developer Studio.

It is trivial that it is highly desirable that the IPU should complete all the required calculations as fast as possible. Just like the CPUs and GPUs (Graphics Processing Unit) of the computer industry, different IPUs with different design will perform differently, in terms of the variety of mathematical functions supported, the processing speed and the output quality or even power consumption and so on. But there are always ways to optimize the IPU to deliver a higher performance, e.g., better pipelining / parallel processing, faster clock speed and faster peripherals and buses like faster RAM and RAM bus, etc.

It should be noted that for the same hardware with the same processing power, there is always a conflict between the output image quality and the performance/speed in processing. Just like any computing hardware, if you need to complete the processing job faster, then the calculations are needed to be simplified. As a result, image quality will drop for such a rougher calculation. On the other hand, if there is no compromise made in the calculations and the software algorithms to be implemented in a precise way (well, provided that the algorithms are good and efficient enough in the first place), then the processing time will become longer and this would affect the continuous shooting rate, with this increase in the processing time for each of the frame.

Actually, the amount of image data to be manipulated is quite huge. Just see how long for our PC, of which the CPU is already quite powerful indeed, will need to convert a RAW file. Then you will see actually the on-board conversion and compression must have some compromises. Also, without the hardware IPU for all those, it is nearly impossible to complete the task in “real-time”, as the delay / waiting time will be too long to be acceptable, when the camera is used in the field.

Despite the specs of the Pentax IPU used the K10D are all unknown to we typical Pentax users, e.g., how many *hardware* calculation functions it supports and how fast or slow it processes things, actually the end results in the images produced can tell something. And, it’s actually what it should be counted afterall!

Even though I have examined quite some of those K10D samples over the net for months, I still have tried to be more objective. Well, I started a poll here. The pictures in the shootout were all taken by Phil Askey with the same target, with different current 10M budget DSLRs, namely, Sony A100, Nikon D80 and K10D, which are all using the same Sony APS-C sized CCD sensor. You can first try to play the game and see which one you would prefer and then have a look about the poll results.

The poll is now near the end (which will expire on 2.2.07 shortly) but you are still welcomed to make a vote overthere, as long as you contribute honestly according to the fair rules set.

Indeed, there is only one purpose for such a comparison (or something alike) and the poll results are useful for one thing, mainly: it is to find out how (well) different cameras, which is mostly about the IPUs plus the software conversion/compression algorithms, do the job. I suppose the lens factor is minimal as Phil Askey yet knew to choose the best 50mm standard lens for each of the brands to do the bench tests. So, optically, I won’t expect a huge difference.

Finally, I wish to point out about the (huge) mis-concept and/or simply un-substantiatable argument by certain Pentax fans that “the image quality is not inferior, it just produces softer jpegs which allow the users more room to do further post processing”.

But, IMHO, I’m afraid that this kind of statement is actually totally groundless.

First of all, if post processing is important, why bother to shoot JPEG? Why not shoot RAW in the first place if so? Do note that JPEG format is having only 8-bit per color per pixel which is far less than the typical 12-bit data of RAW. Indeed, the true value of the JPEG format IMHO is just to provide an option for direct out-of-the-camera “instant” product. As the main purpose of the JPEG mode is just for convenience and thus it should be highly preferable that it should look great when it is output.

Secondly, I must point out that “softness” is actually a totally different thing from “blur” or simply “bluriness”. A “soft” image means that it is less sharpened, as this is exactly what people who are defending always arguing about. Blur(iness) means that there is less picture/image information/data contained and that the image is not clearly defined and is somehow in a mess. This is merely a result of inferior and poor processing. The worst thing is that when there is poor processing, digital artifacts will often appear and come out altogether, e.g, obvious zigzag edges in JPEGs.

The truth is when the above happens, sharpening cannot help in any sense. Yes, sharpening can make the picture *looks* sharper, but the lost image data can never be retrieved in any way and an ugly duck can by no means becomes a princess, which can only happen in a fairy tale!

For anyone who is still unconvinced, one can feel free to visit my K100D full review page and download the original “soft” Jpeg image produced by my *ist DS and the corresponding Jpeg image direct out of my K100D and then apply sharpening/USM (or whatever you like including increasing the contrast and etc.) so as to see if you could do the miracle!

Last but not least, I must second the views of Phil Askey here this time as I believe he actually knew very well for how to draw up his conclusions in his reviews, which are widely publicized, and most importantly (to him), how to write his conclusions carefully with his excellent native English. BTW, I have nearly never been able to find anything he said in his review conclusions is obviously wrong. This also explains why he is so authoriative and is widely and highly trusted by the photo gear consumer community.

Nonetheless, I can see that Phil Askey have already been quite restrained in using his wordings and sentences and usually tried to give a leeway for each of his comments which can be considered as “negative”, frankly speaking. Indeed, it is not difficult to see these in his *ist D and K10D and other reviews. Well, by inspecting his “lab” test shots as well as all those real-life samples, I would say that quite some of the (K10D or *ist D) pictures are “blurry” when viewed in 100% or so, but Mr. Askey was still being very kind in just saying “soft” or “lack of edge sharpness”. If I was writing the reviews with Phi's test data, I would have used the word “blur” long time ago to represent things in an even more accurate and exact way. Well, to talk about more positive results, I think Phil is again right for his favourable conclusion on the image quality of K100D, which I have made up a similar conclusion in my K100D full review months before Phil published his report :-) BTW, as Phil Askey mentioned, I too scratch my head hard from time to time why Pentax has ever only done the thing right *once* with the K100D *only*!

So, when there are quite some die-hard blind brand loyalists at the DPR Pentax DSLR forum bashed and bash Phil Askey from time to time for what he writes (which are already in a restrained way), I think those guys should give a big thank to Phil instead, if they could really face the truth by doing more researches and thinking a little bit more objectively.

If unfortunately and yet fortunately you are one of those who are now reading my article to this point, what I can say is only: “Sorry, I just tell my best knowledge and express my truly humble opinions..” If *you*’re still not convinced, please download and inspect thoroughly again for the posted images in the “Compared To” sections of Phil Askey’s review reports. If you still can find something new and different with good evidence, any further discussion in a peaceful way will be much welcomed.

Read also:-
Dpreview puts Low Rating on the Image Quality of K10D

The Secrets of the K10D (Part 2 of 3) – The Bridge: The A to D Convertor

The Secrets of the K10D (Part 1 of 3) – The Heart: The CCD

Friday, January 19, 2007

K10D Firmware V1.10 is Leaked!

The K10D latest firmware update, version 1.10, has been leaked before the official announcement, of which the date is rumoured to be the 23rd of January! Here is the download link for the shared zipped file for the whole package, which includes the binary firmware file, a smmary on the firmware changes, an user guide for the additional features and a standard readme.txt reminder:-

http://www.4shared.com/file/9096751/9934950f

*Update on 20/1*: The shared file has just been removed! So, you folks would better wait for 23/1, for the official announcement!

Here is a quick glance on the changes (and I link to some of my previous reports on those problems/limitations catered by the changes):-

Changes to V1.10

The following function has been added in version 1.10

1. Wireless control of external flash through built-in flash.

2. Instantly return to centre AF point by one push of button in AF select mode.

3. Possible to change ISO setting by dial at TV/AV mode.

4. ISO setting change by dial while the ISO setting is being displayed on the LCD by pushing OK button.

5. Green button function in M mode is available at TAv mode (Hyper manual).

6. AV and TV switch by dial at P mode.

7. Instant return to the default value by green button at strobe light compensation.

The following contents have been corrected.

1. In rare case, vertical stripe at long time exposure.

2. Released “B exposure” and show battery empty sign when using B mode.


The firmware file has indeed already been installed by some K10D users and below is one of them who have shared his successful experience:-

http://www.dchome.net/viewthread.php?tid=308230&extra=page%3D1

(Post messages are English and Traditional Chinese mixed, use Babel Fish to translate if needed.)

This time, I really must say "Well Done, Pentax!", as it seems that they finally (and for the first time I have ever seen) could listen to us, the Pentax users and their customers, for the bugs / limitations reported and could have reacted promptly for solutions to the problems! Most importantly, they are now admitting problems and do not avoid to mention these in their official documentation. Actually, they have also done a few tweaks for additional features which can improve the operation, or at least, there are now more options for operating the camera.

Still, the effects and actual improvements in the field for those critical issues, like occasional(?) banding(s? more than one type?), 32 second limit in bulb mode and etc., are yet to be proven.

In this right direction, I guess there is the hope of my Blog to have less (and hopefully less and less) "negative" reports about Pentax gear in the future!

Anyway, whilst quite some of my reported stuff have already been rectified in this firmware update, do note quite some other undesirable things like Hyper Program Defeats Auto ISO and etc., which I have also reported here, are not yet fixed. Hope that these will be overcome in the next update! Good luck, K10D guys!

BTW, as a K100D guy myself, I still hope that there will be a K100D firmware update soon to eliminate those long-lasting (Pentax) primitive problems which are already non-existent in the K10D, like the defeation of Auto ISO by the EV Compensation. Of course, it will be much welcome if K100D can also have all those "limitations" which have already been eliminated for the K10D, in the latest firmware, like the inability to control external wireless flash by the built-in flash.

Saturday, January 13, 2007

Focus Calibrations for (Pentax) (D)SLR Bodies and Lenses

From time to time, there exist DSLR users report about different AF issues, regardless of brand. Nevertheless, the fact is that some particular DSLR or lens models are being reported by more users than the others. It is just because either that those particular models are indeed less accurate or simply that they are more popular (so that there are more users to report, by proportion) or both.

For example, for those reports on AF issues about the K10D, you can refer to my previous Blog entry:-

http://ricehigh.blogspot.com/2006/12/af-errorsproblems-of-k10d.html

In this article, I shall talk more in-depth about the essentials of focus calibration for (D)SLR bodies and lenses, by first discussing into the working principles and design of those equipment, in general sense, and then particularly about Pentax gear on the possibilities of how to get those stuff correctly adjusted, totally or maybe just partially.

Actually, a camera is a precision tool which means that alignments and all those distances within it (which means both the body plus the lens for what is meant for a camera) must be *calibrated* to a high precision with adequate accuracy. In order to achieve this requirement, first of all, the design of the focusing system by itself, no matter it is an AF (Auto Focusing) or MF (Manual Focusing) one, must be accurate *enough* by itself. And then, good calibration procedures are required to ensure the accuracy by making proper precise alignments, for all those adjustable variables in a design. Well, the (process of) correct adjustment of those variable physical parameters is the "calibration".

So, one will ask how much precision is required for a focusing system? Or, what is an “adequate” AF system? Last time, I have some talks about the possible precision requirements about the design of an AF system (and the importance as well), you can have a look on this first:-

http://ricehigh.blogspot.com/2006/12/how-af-errors-can-decrease-effective.html.

By the way, I notice that many people are often confused about different phenomenons of the focusing problems seen and the respective causes underneath.

Indeed, different focusing problems are often caused by a combination of an inferior design (with inadequate accuracy – just because manufacturers are cutting corners, but they are just doing that too much, far beyond the limits), poor alignment(s) and calibration (which is also often the case). Or even worse, the problems are caused by loose and poor QC at the factory or maybe just the alignment department in the production line are doing a bad job in the first place (well this is somehow closely related to the proper design of the manufacturing process *plus* the “quality” of the factory workers on how they are faithfully and accurately doing their jobs as required).

Well, in the following, I shall summarise the key major technical aspects of the (AF) SLR focusing system, their significancy, and the possible adjustements allowed for Pentax DSLRs:-

I. Accuracy in the Back-focus Register Distance of the Body

Note that the term “back-focus” used here is by no means related to the Back Focusing (BF) problems reported by the DSLR users daily. That is actually about the distance measured from lens mount to the focal plane, which this distance is the basis of how the lens system should be designed as it is the fundamental parameter for all the optical calculations involved in any optical formula thereafter.

Do note the back-focus distance is generally referred to the distance from the front of the lens mount to the focal film/sensor plane where the sharp in-focus image should ultimately arrive. However, the exact point of reference for the measurement does not really matter as long as the thickness of the body mount is known and then everything is relative (in displacement).

Here is an interesting article for a case study about the back-focus register distance of the Hexar Range-Finders (RFs) and the assoicated implications:-

http://www.dantestella.com/technical/flange.html

It would be interesting to note that the choice of the back-focus distance is dependent on the film/sensor size as well as the optimal focal length chosen as “standard” (for the “standard” lens, with a standard field of view). For example, the back focus distance of 35mm cameras are optimised for standard lenses in the range of around 40mm to 60mm. Beyond that, lenses are more difficult to be designed and built as optical formula will become more complicated. Of course, it’s normal that a longer focal length lens will be more bulky and it’s the Physics.

Afterall, if the lens is designed to assume for a certain back-focus register distance but unfortunately a body is made to be having a wrong one, either shorter or longer, then irregularity will result. Just say if the back-focus distance is lengthen, the camera may not be able to focus sharply at infinity (remember human short-sighting owing to long eye balls?).

So, what can be adjusted for Pentax DSLR Body?

I’m afraid that the answer to this question is “virtually NONE”, from my experience! My Pentax *ist DS was having a slightly longer back focus register distance so that many of my Pentax lenses (mostly primes), which are correctly collimated for the infinity, could not achieve focus at infinity. My local Pentax service centre had adjusted my *ist DS body to make it FF a little bit so as to “resolve” the problem. But after that I discovered my *ist DS tends too much to FF, so my unit was finally sent back to Pentax Japan for repair, but then Pentax Japan opted to adjust the AF mirror angle to “rectify” the error, but then the whole AF sensitivity area was shifted out of the marked area (despite that the original problem was solved). For more details, you can (always) read this:-

http://www.geocities.com/ricehigh/A_Letter_to_the_CEO_of_Pentax_Corporation.html

BTW, this physically wrong back-focus distance can cause troubles to the AF system if the this is one of the parameters involved in the *cor-relation* between the (sub-optical path of the) AF system and the actual optical path for the exposure, which I would explain more in the next part below.

II. Accuracy of an AF system (for its design, manufacturing precision and alignment)

1. "Range-finders"

Starting to elaborate more about the case, one can think about the focusing mechanism used in those RFs in the good old days (when mis-focusing cases rarely happened). The rangefinders have separate optical focusing system in the viewfinder, so precise alignment for an accurate “cor-relation” is crucial. Same happens for AF SLRs where the AF system is a separate system optically (putting aside the electronics sensing element) and it has its own optical path (and sub-paths as well, that will explain more below).

Strictly speaking, as long as the focusing department of a camera is concerned, AF SLRs can be considered as range-finders but not true SLRs. The only difference is only that the human eyes for doing the focusing job, ultimately, are replaced by the AF sensors (CCD or CMOS, which doesn’t matter anyway).

2. Why MF SLRs are usually more accurate?

Actually, the manual focusing principal of MF SLRs (also AF SLRs in MF mode) by utilising the focusing screen can be easier to achieve a higher level of accuracy. It is not because of the technology is proven, but just because of the design is much simpler, and involves only optical device instead of optical devices plus lectro-optical electronics, and, most importantly, the optical path is simpler, too.

The critical alignment of MF system rely mostly on the up/down position and parallelity of the focusing screen (plane) , which should precisely lay on the reflected focus point, by the main mirror of the SLR.

For more read on how the focusing screen can focus accurately with the aid of split prisms and/or microprisms and how these work, see this super clear technical article (one of the best technical articles I have ever seen on the net about cameras):-

http://doug.kerr.home.att.net/pumpkin/Split_Prism.pdf

3. Why AF SLRs can be even more inaccurate?

As you can see from the above technical article also that SLR AF system is rather complicated in its optical structure and its components are made in a very tiny way. So, a very high precision is required for making each of all these.

Besides the difficulty in making proper alignments for an AF system owing to its complexity, there are even more things to affect its accuracy. These include the optics for projecting the image to the AF sensors (which are not perfect, optically), the sensitivity and limitations of those sensors, analog and digital signal processng of the AF siganals including the software algorithms used in the phase-matching/detection and etc.

BTW, here is a detailed bibliography showing the technical details of a typical (Pentax) SLR AF system:-
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=JP2004157212&F=0&QPN=JP2004157212

By looking at the side cut view of the AF module, one can have an idea how the physical path of projected image is, starting from the lens and then the light ultimately reaches the AF sensing module.

4. The Latest Pentax Design (of the SAFOX VIII)

Here is the very recent filed patent for the Pentax AF system (which probably is the central 9 (cross sensor) points of the SAFOX VIII):-

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US2006120711&F=0&QPN=US2006120711

It can be seen from the drawings and the descriptions that the design of the (SAFOX VIII) AF system is very complicated. However, technically it is basically of not much different from other systems and it is exactly the same of the Canon 20D’s one, for its design andworking principle, from what are described the last technical article I have pointed to.

As briefly mentioned just before, for all those numerous but tiny AF optical elements involved, e.g. those micro lenses, micro-prisms and/or mirrors. Each of those elements will undoubtedly introduces certain optical and alignment errors by themselves as nothing is perfect in this world. So, they can add up to a much larger error, especially those errors can be greatly magnified owing to the small size in the detection system and hence the components in the AF module.

All in all, the simplest focusing system will be the best in terms of accuracy. For the design of an AF system, I would rather ask for quality than quantity. That says I prefer a single high grade and high precision and well calibrated/made linear AF area in the AF detection module rather than numerous low grade sensors placing around which I would seldom use (except I give my DSLR as a P&S to some laymen to hold my camera and shoot). All those saved material, manufacturing and labour cost for such a greatly simplified design can be re-used for making a much better AF system, frankly speaking, e.g., a more sensitive AF sensor, an AF sensor with higher pixel density (so that the AF calculation will be more precise and the minimum f-stop for AF to be workable can be made smaller – just look back to the last focusing system technical article above if you don’t get exactly what I mean here), more precise micro-optics with more corrections in optical aberrations (which are all unlikely to be calibrated, but are only dependent on the precision of the design and the “mould”) as well as spending more labour costs in ensuring the “outside” alignments, which are adjustable, and etc.

Nonetheless, I have verified in controlled environment that my MZ cameras (MZ-S and MZ-30) or even the 1987 SFX are more consistent in AF results (i.e. the final AF points are usually close enough no matter how the user does the AF, say, AF starts from infinity mark or nearest of the AF lens) and that different lighting conditions such as the color temperature of the light source, lighting level, etc would cause minimal errors. In fact, the texture and pattern, e.g. color and spatial frequency of the object affects the reliability of the AF too. Here, I know that the best AF system is still the central sensor used in the MZ-S, although it is not a crossed one!

The SAFOX VIII used in my 3 models of Pentax DSLRs are not something that I can really rely on as I used to with my MZ-S. Actually, I do have seen improvement / debugging of the SAFOX VIII with my K100D than my old *ist Dx. However, the AF system of my K100D still behaves somehow inconsistently and the yellowish tungsten light can fool it easily and in a large amount.

To do simple experiments to verify, any Pentaxian can mount their own DSLR with a fast prime on a tripod, does AF on an object, focusing from infinity and then from closest and repeat for a few times. To compare, repeat the test with different camera models (if available) and/or under different light sources or even for different objects (with different colors, spatial frequencies and contrast levels, etc.). Then, you’ll see the AF system of those MZ cameras are undoubtedly more reliable and accurate, although marketing wise they are not as “sophisticated” as the latest SAFOX VIII, at least on published papers!

The yellow light symptom of Pentax DSLRs is a great annoyance which means that the effective resolution of the DSLRs are greatly reduced owing to the significant (front) focusing errors under tungsten. Again, here is my old quick experiment to confirm the problem:-

http://www.geocities.com/ricehigh/DS_AF_Dependency_on_KEV.html

5. So, what can be adjusted for the Pentax DSLR bodies?

Someone told that the plane of AF module is seated on a plane that is adjustable, see the post with diagrams/photos showing the “secrets”, below:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=19960398

After we see about the working principle of any focusing system in the above, I think now that we know about this is exactly to adjust the plane of “perfect focus” for the AF module. Well, I have checked against the relevant Pentax patent to further verify this::-

http://v3.espacenet.com/textclam?DB=EPODOC&IDX=JP2004157212&F=0&QPN=JP2004157212

Furthermore, I know that there is a "secret" port underneath the bottom plates of Pentax DSLRs. A physical connection can be established via the port and then
a Pentax servicing utility can be loaded. This utility can do some additional calibrations software-wise including the input of the FF or BF offset amount.

III. Lens Collimation

“Collimation is the adjustment of a given lens to a camera body, so when on that particular camera body the lens will provide correct focus to infinity as well as to the lens scale settings”:-

http://lavender.fortunecity.com/lavender/569/lenscollimation.html

Well, again it is NOT something to do with those FF and BF issues, which are all about the inadequacy, inaccuracy and off-calibration of an AF system (discussed in the last part).

In fact, the most significant part of the lens collimation is at/for the infinity position, of which the collimation calibration should get the position exactly right. It is the most important because the near distance and middle distance can allow for some deviations which will not prevent the user from getting the right focus for the shooting, it’s just that the distance scale does not tell the exactly right distance for what the scale shows. But at the infinity, there might be no more room for the body/lens combo such that the lens can never focus/reach infinity. To cater for this problem, most current cheaper lenses will allow more room beyond the infinity but yet the camera makers do calibrate at the infinity mark at the focus scale. As such, a looser calibration & QC or simply the manufacturing tolerance can be allowed. In the past, they did this only for super telephoto lenses, which the collimation position of the lens is sensitive to change, e.g., with temperature.

So, what can be adjusted for Pentax *Lenses*?

As most of other lenses on this planet, I believe all Pentax lenses can be adjusted for the collimation. Here is a set of procedures extracted from the service manual of the Pentax FA 43/1.9 Limited lenses:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=15072863

The missing diagrams are exact scans from the Pentax maintenance manual, which has already been deleted by the poster, who knows very very well about the technical insides of Pentax gear. Indeed, I have learnt so many things from this knowledgeable guy in the past.

Here is the quote from the post for the procedures:-

“First you need a piece of rubber to unscrew the large retaining ring in front, then 3 screws underneath.

Peeling inside and you will see 3 black colour screws with washers (see pic below). Loosen them a little (don't remove them completely) then you may adjust the focus. When done, tighten them again, and apply light duty threadlock on all screws. It is important to remember never overtighten them because the aluminium alloy is rather soft.”

Just say if you have a body with wrong back-focus distance, physically, one can indeed do the collimation for all the lenses he had that will be mounted on the body. However, the focus collimation of such adjusted lenses will not be exactly correct for another normal body which has the correct collimation (back focus distance), so it is not wise to do so afterall.

Saturday, January 06, 2007

Pentax Comes in the 3rd Place in Japanese Home Market Sales

Here is a latest Japanese report on the detailed sales figures and volume of DSLRs at the Japanese home market:-

http://bcnranking.jp/flash/09-00011835.html

(To translate Japanese into English, you can use Babel Fish)

It can be seen in the first table that Pentax are doing quite well with their K10D, for the number of units sold so far, whereas the K100D is yet ranked at no. 9, within the Top 10 also.

And then the second table shows that Pentax has already caught up in the game and being slightly ahead of Sony, in terms of the total DSLR sales in December 06, and now they are at the 3rd place ( or the 2nd runner up if you prefer even a smaller number :-) ). Surprisingly, Nikon has already beaten Canon marginally with their numerous models of D40, D80, D200 and D50 (ordered in the accumulated number of units sold). Still, the Canon 400D (XTi) is still the King of the current DSLRs.

Congrats, Pentax, please keep it up!

Nonetheless, I do believe that if Pentax could have re-solved most of the commonly reported significant problems by their users (which I have summed up and will report in my this blog) and that they did react positively about the user feedbacks on all those annoying things, undoubtedly they could have done even (much) better!

Monday, January 01, 2007

Reports on In-effective Dust Removal of K10D Continue

Further to my last report more than one month ago:-

http://ricehigh.blogspot.com/2006/11/effectiveness-of-pentax-dust-removal.html

Here are yet continous feedbacks about the ineffectiveness of the DR system of the K10D:-

http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=21464901

By following the thread, it can be found that people do in general believe that Olympus do have the most effective dust prevention solution for DSLR, which is far superior, whereas the Canon 400D/XTi's one comes in the second place, whereas the Pentax DR in K10D is the most ineffective one :-( Too bad..

Again, I hope this is not true (but objectively it tells the opposite). Pentax, again, I urge you please try hard to keep up! And, most importantly, don't avoid user feedbacks and do face all those real problems!

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