Pentax k7 focus problems, quality control.

[vasilis]

<p>Hi all,<br /> It has been a long time since I have last contributed in photo.net. The reason I am writing is my adventure with Pentax k7. I live in England and at the beginning of November I decided that my cameras needed a total upgrade, I had a nikon d70 with some lenses, flashes etc (24-120, 50, 10-20, sb600). I decided that I would like to go for something different and try Pentax k7.<br /> I started the process of selling things in ebay, I bought the first pentax k7 from Amazon, which had a non-functioning main e-dial, with also a tamron 17-50mm 2.8 and a afg340 flash unit. I returned the k7 to amazon and then got a new one from amazon. The k7 came and seemed to be functioning ok except I found the focusing, to be not slow, but unreliable. Meanwhile we had our newborn son, so although I did snap photos of him I never took the time to look at the photos in any detail.<br /> But I was not exactly happy with the setup, I started realizing that the 17-50mm focused at different focal planes at 17mm and 50mm. I suspected that this was due to camera because I can not understand how a lens can back-focus or front-focus since the camera decides focusing. I sent the lens back, starting to be prepared for the worse. I found in a shop called SRS a Zeiss 1.4 manual planar lens and I ordered to check the camera. Since it had 1.4 aperture and was fixed focal length I thought that it would show problems with the camera. The lens arrived and the camera front focused using the manual focus and also front focused using the autofocus, autofocus and manual focus agreed with each other but the sensor did not agree with them. This would mean that the sensor plane is at a different distance from the mirror than the autofocus and the focusing screen is! I called the shop (SRS) and they told that I should bring the camera to them and test it. I visited the shop where the responsible confirmed my theory; we tested a different lens, the camera was doing the same thing. Then we opened two other pentax k7 cameras and tested lenses on them and they all behaved the same way. They front-focused enough to be detected at apertures 1.4 up to 2.8 at 50mm! We concluded that pentax has released a series of pentax k7 bodies with wrong distances in the sensor plane! Most people will not complain because at 2.8 you can tune it with the AF fine tune and at 3.4-5.6 where the kit lens is it is not apparent.<br /> SRS is maybe the most important dealer of pentax cameras in the UK, I have to note that the sales person that was dealing with me had for his personal use a nikon (although this is just a juicy detail). I bought there and then a used nikon d300 returning back to the company with which I was at the beginning but with significant losses as all my nikon items are sold to ebay. I returned the pentax k7 to amazon and they refunded me, I am still waiting a refund for the lens and now I have to find what I will do with the flash.<br /> Now with the Nikon d300, I do not have all the nice things that I would with pentax (eg vibration control) but I have a camera that reacts to your inputs in such a way that you can trust it. This sounds like a very general criticism but it is absolutely true! I am writing to communicate my sadness towards pentax as in paper their cameras seem fantastic on paper but with their quality control they have lost a customer probably forever. Mainly though I am writing to see if other people had the same experience, it seems like a significant number of pentax bodies could be affected, although it may be a characteristic of the bodies imported in the UK!<br /> Vasilis</p>

<p> </p>

[personalphotos]

<p>I'm not blowing "Pentax Smoke" at you in saying that this is not an issue. I'm a moderator (with 8100 posts) on another Pentax only forum (20,000 + members) and I also own several DSLR's as I make my income with Pentax cameras and wouldn't if QC were that bad.</p>

<p>I read daily, the positive and negative comments posted. BF and FF are not issues. Rarely discussed and certainly no more than any other brand. BF/FF can happen with (and does) with any camera and isn't an indication of QC. In fact all the other brands have some form of BF/FF adjustment in their better bodies for a reason. It happens to all to a limited degree.</p>

<p>Did you get a bad first body, sure that happens but I don't think so on the second one. I certainly don't think there are or was a batch of bad cameras shipped to distributors. You are reporting your experience as if all the cameras sent to the UK were bad. That doesn't add up.</p>

<p>I hope you enjoy the new D300, nice camera.</p>

[vasilis]

<p>Whatever I wrote to the post was true, I have tested 4 pentax k7 bodies, 1 of them had a malfunctioning e-dial and I did not check the focusing and 3 of them exhibited front focusing. This is my experience, your conclusions from this story maybe are different than mine.<br>

I do not really care if other companies have the same problem, fine focus adjustment solves the problem for the focusing in the auto focus sensors but not in the manual focusing case. If you believe that a camera that does not manual focus properly is acceptable and you would have kept it, then probably we have different expectations from cameras. The reason though that I wrote the post is to see if other people had a similar experience.</p>

 

[personalphotos]

<p>I had no idea from your first post that you had tested 4 bodies. I missed that detail in the first post, sorry. It begs a few questions. Maybe there was an issue with a small batch? I sold electronics for 12 years and I've seen shipments dropped that damaged the entire pallet. Who knows what happened between the factory and the store? Maybe the lens used was faulty? Maybe the testing method was in error?That happens a lot.</p>

<p>MF focus lenses can have various issues. These screens were never built for fine MF use. There's no split screen like the film days, The ground glass is not even close to what we had on a film body, the VF is dimmer. I can list a dozen reasons that MF lenses would be a challenge.</p>

<p>Sorry I don't want to argue and I certainly would never say Pentax is perfect. I have my own issues. But I'm a heavy user of the brand. I own 12 MF lenses and 11 AF lenses. I have 4 bodies now and have owned 7 since they came out with the first DSLR. I've shot close to 100,000 frames since the *istD came out then 25 years with Pentax before that. Literally thousands of those frames were paid work. I've seen some lens issues personally (BF-FF on DA* lenses) but nothing systemic with a particular body. That's both personally and in my role as "hall monitor/moderator" on P.forums.It's just odd that it's the first we've heard of a batch problem with the K-& regarding FF/BF. And that's not to say there haven't been some issues with the body. For example they first came out with a faint green line showing up in sensors that were getting too hot. A firmware fix cured that rather quickly.</p>

<p>Your e dial issue could be real or it could be a grip problem. You didn't say if a grip was tried. If so there's a common little issue that grip owners are aware of. The grip when on can have it's E dial fall between two "detent" points and thus lock up the same E dial on the body. It's a simple fix, just rotate the E dial on the grip to a detent spot and keep shooting. Or turn the grip off.<br /> <br /> So again I don't want to argue, but there can be a lot more to this that appears on the surface, I wasn't in the store. It may all have been accurate or some of it could easily been user error.</p>

[personalphotos]

<p>Also a further thought, I personally have bought 2 lenses that were defective and BF'd on 2 different AF DSLR bodies. The bodies worked perfectly with all my other glass. The lenses were returned and replaced without issue and the replacements worked fine. It's not common but possible that a lens is the problem and not the body.</p>

<p>Second, what was the testing method? Was a test chart used? Tripod or hand held etc. Testing done indoors with tungsten light can be an issue. It can throw off the AF sensors. Was any testing done in controlled conditions outdoors or in natural light? There are many variables that can effect the outcome.</p>

[vasilis]

<p>Peter, all your comments are valid and as you would expect the testing in the shop was not scientific, but it was enough to make the dealer mad! However the errors that you describe or the difficulty to manual focus would make the tests to give random results meaning that the focus point would be random, but what happened was that all the lens-body combinations manual or auto focus gave the same consistent slight front focus which was apparent at low apertures (1.4 - 2.8). On the other hand live view focus gave correct focus (as you would expect). Now, for this to happen, the only logical assumption is that the distance between mirror and focusing or phase sensors is the same whereas the distance mirror-sensor is slightly different.<br>

I am not saying that all pentax k7 have the same problem but I would be interested to see if other customers, especially in the UK had the same experience. Don't think I am happy to have this adventure, I would very much prefer for the K7 to work, if not for anything else, this zeiss planar was an amazing lens!<br>

Vasilis</p>

 

[laur1]

<p>I am sorry to hear about your trouble Vasilis.<br>

I am also wondering why you have never posted here when you had these problems with a Pentax camera and when our advice might have helped.<br>

I use manual focus pretty much all the time and I shot a lot recently at f/1.4 with my K-7. I haven't noticed any problem with the camera when manual focusing. Also, getting the Pentax magnifier loupe for the viewfinder has considerably improved my ability to manual focus accurately. Most of the time when my shots are failing it's due to subject movement, my movement, or slow shutter speed, not because of the camera.<br>

Were your test shots taken using a tripod or were they handheld? If you used a tripod, did you try focusing via LiveView as well - if it worked, did you check to see if the viewfinder view didn't look in focus? LV focusing should use the sensor for focusing, so if your theory that the sensor was misaligned was right, it should be the only method to work.</p>

[garydem]

<p>i echo what <a href="/photodb/user?user_id=3668464">Laurentiu Cristofor</a> states above. you had a f1.4 zeiss lens. are you aware that at f1.4 you dof is paper thin. even the back and forth swaying of your body holding the dslr is enough to throw the focus completely out? so what you focused on is now if you shoot at the back or front of the sway is now out of focus. and it does not sound as though you are doing any focus tests with the dslr on a rock solid tripod with cable release. if you are doing focus tests hand held YOU ARE WASTING YOUR TIME. your body has too much movement to make the test valid. not to mention why are you manual focusing? i have never found a real good reason to do so. the AF is fater and lets me frame and compose the shot instead of focusing.</p>

<p>i have been shooting pentax since 1970. that is now 5 bodies and a lot of lenses later. for a lot of years i was manual focusing. the reason AF was not invented yet. when AF came out i thought it was the greastest, now i could compose the shot right without diverting some of my concentration to focusing.<br>

you know in all those yrs of using pentax lenses. i never ever ran into a BF/FF issue. is there an issue or is it just that the user can now test for it and does because he can. i currently have an istD and a k20d. the k20 has AF adjustment. during this summer before going on a 6500 mile drivimng trip i hauled out my 12 lenses, including a 500mm MF mirror lens. and did the AF check i found only 3 that i changed the AF point on, even then the amount was just about the minamum. even the 500mm MF mirror turned on the foucs light when it was in focus. i am fully aware that the small amount of AF adjustmnet that i did would be swallowed by the fstop dof for any pic i would be taking. i have never had a AF problem with the istd and that is using the same lenses, including the 3 i adjusted for in the k20d, with the same lenses. all gave sharp images.</p>

<p>if you think that going to another maker will solve your problems with the dslr/lens then you are in for a shock. you simply have the same ones or end up with other issues.</p>

[vasilis]

<p>Hi Garry,<br>

Now, I remember why I have not posted for so many years in photo.net or any other photographic forum. People are so happy to give plenty of wisdom or credentials. Well, if we are applying for a job my credentials are that I have a BSc in Physics, an MSC in Optical fibres and a PhD in optics and lasers. I am an academic with research in optics, lecturing electromagnetism, also I use cameras in the lab, attached to microscopes for laser beam profiling. When I write down that the k7 had focusing problems, I know that it had and this was not my question. I do not care if you shoot pentax or whatever for the last 7000 years, if you own 10, 20 or 50 lenses. The reason I wrote the post was not to be lectured on the difficulty to do a correctly focusing camera, it was only to see if other people have experienced similar problems with pentax.<br>

I am sorry for taking the space and thank you very much!<br>

Vasilis</p>

 

[jeremy_corbin]

<p>I'm no expert, but recently I wasn't able to manually focus easily either on my *ist-DS.... but I discovered why: Did you check the diopter settings on the VF? If Live View could see fine, but you couldn't.... Maybe it was the default setting on the diopter on all 4 bodies you looked at... I wear contacts.... when I take them out and focus without them I need to adjust the diopter....</p>

<p>Just a suggestion.</p>

[jgredline]

<p><img src="http://i404.photobucket.com/albums/pp128/jgredline/troll-web.jpg" alt="" /></p>

[personalphotos]

<p>Doug shut this one down. It serves no useful purpose. We pedestrian folk are not at the level of Einstein up there. Just that a few of us know these cameras inside and out and can say with good certainty what the issues really are.</p>

<p>As I said in my earlier post, I read literally thousands of posts as a moderator on another forum as well as most threads here and this situation has never been reported in this fashion. BF/FF issues are very rare since the DA*16-50mm issue was corrected.</p>

<p>If that's not enough for Sir Issac Newton, well sorry we simple fools can not meet Vasilis's expectations.</p>

<p>Regards,<br>

Petro, Tzagarakis<br>

Aka Peter Zack<br>

Hania, Crete</p>

[jim_landecker]

<p>Well, I just got a lightly used K-7 and am finding a similar front-focus problem with manual lenses. I also just tried to buy a Tamron 17-50/2.8 which front focused horribly - too far for the AF compensation to correct. I tried two other 17-50's in the store with the same results, and also on their demo K-7, with which the problem was not as bad but still there. Maybe this is just as much an issue with the Tamron lens as the body, but it's not too reassuring. I was thinking of sending my camera in to have it checked by Pentax. Since manual focus is a bit of a secondary function with these cameras, I wonder if the adjustability and QC of this aspect is not as good as it used to be with MF cameras.</p>

[laur1]

<p>Regarding focusing problems there was also this interesting article I've come across and posted here:<br>

<a href="http://www.photo.net/casual-conversations-forum/00VCLu">http://www.photo.net/casual-conversations-forum/00VCLu</a></p>

[michael_elenko]

<p>Not owning a K-7, I won't comment about its focusing performance. My sympathies are with Vasilis and Jim, no one wants a new (or nearly new) camera to fail in such an elemental way.</p>

<p>I have owned the Tamron 17-50mm f 2.8 for a year and a half and use it regularly on a K20D. Optical qualities aside, this lens is known to have a variety of focusing issues on all platforms. A simple web search will reveal the details.</p>

<p>Until I learned to use the AF adjustments in the K20D, this lens needed manual attention more frequently than any other AF lens I've owned. After the AF adjustments (and none of my other AF lenses needed as much AF adjustment either), the AF performance was better than acceptable.</p>

<p>So, I guess the point of my post is that the Tamron 17-50mm f 2.8 is not the best lens to use as a reference for baselining AF performance in a DSLR.</p>

<p>Since we're on the topic of focusing manually on DSLRs, I will strongly recommend the purchase of the Katzeye Ultra-bright split screen. Very effective, worth the money, and a joy to use.</p>

<p>ME</p>

[michael_kuhne]

<p>If I recall correctly, when moderator Justin Serpico obtained a K-7 a few months ago to use and assess, he also ran into off-focus problems with many of his lenses. Problems he did not have with his K10D, nor the K20D he previously had for a trial. He was evidently able to resolve the issues by using the K-7's custom AF adjustment. Only speculation, but we did wonder about QC with this model, and maybe the type of video mechanism in the design having an adverse affect, throwing the AF out of the groove.</p>

[laur1]

<p>I have heard complaints about AF being off-focus for both K10D and K20D, so really, this is not indicative of any problem with K-7 in particular. And it's a complaint brought against camera models from any manufacturers. lensrentals that I mentioned above doesn't seem to rent much Pentax equipment - they're mostly renting Canikon and they still get lots of these complaints.<br /> @ME: I considered getting a better focusing screen, but AFAICT, they really only help you focusing if the area of interest is in the center of the frame - or am I missing something? I used recently an MX and a K1000 and I had to place the area I wanted to focus on in the center to get the benefit of the focusing aid - while this works great for certain subjects, it's not an option for others.</p>

[vasilis]

<p>To Laurentiu,<br>

I understand that AF was off in other models, what surprised me was that manual focusing was off. Also the article from the lens rentals, I do not understand it. A camera may front-focus or back-focus, but a lens cannot. Meaning a lens may have a problem with a non planar focal surface (most of them have by design) or by being decentered etc.. However it cannot have the problem of front-focusing or back-focusing: the camera decides and stops the lens when it is in focus in autofocus mode, or your hand stops the lens when you think it is in focus in manual focus mode. If afterwards, the picture is soft it means that the distance mirror-sensor is different to the distance mirror-AF sensors or mirror-viewfinder (in the case of manual focusing). What I do not understand is why the camera industry thinks that we should be tolerating cameras that font-focus or back-focus, there is a general acceptance, that this is so common that it is ok!. I do not understand that, absolute 100% correct focusing is a basic requirement for any camera.<br>

Also for the focusing aid, the only way to do it is to focus in the center and then pan and hope that you have not changed your distance to the object!</p>

[michael_elenko]

<p>Laurentiu C wrote:</p>

<blockquote>

<p>I considered getting a better focusing screen, but AFAICT, they really only help you focusing if the area of interest is in the center of the frame - or am I missing something? I used recently an MX and a K1000 and I had to place the area I wanted to focus on in the center to get the benefit of the focusing aid - while this works great for certain subjects, it's not an option for others.</p>

</blockquote>

<p>For the Katzeye "+" screen that I have used for the past year the advantages over a traditional SLR screen are many and tangible. The center "split" area is significantly larger than the standard SLR screens are (I used SLRs for 24 years prior to going with a DSLR). A nice touch is the very large concentric circle beyond the microprism collar that is an excellent framing aid. Most important is the anti-blackout nature of the microprism. I've found it effective down to f 11. That is unattainable with the typical DSLR matte screen. Furthermore the surrounding matte screen has a brightness treatment that truly works. For someone in their mid-50s, who has worn strong contacts for 35 years, this is outstanding. Please realize that I shoot in one of the greyest places on the planet and all incoming light is appreciated.</p>

<p>Re: the center focus; I usually only have the center focus point activated. If I want something in focus closer to the frame's edge I simply move the camera that way and adjust. That's never been an issue. Perhaps I'm missing something here?</p>

<p>ME</p>

<p> </p>

[michael_elenko]

<p>Vasilis A wrote:</p>

<blockquote>

<p>[deleted] However it [the lens] cannot have the problem of front-focusing or back-focusing: the camera decides and stops the lens when it is in focus in autofocus mode, or your hand stops the lens when you think it is in focus in manual focus mode.</p>

</blockquote>

<p>I disagree with this statement. Both from my own experience and those of multiple reports from Tamron 17-50mm f. 2.8 users. Just spend 5 minutes reading Amazon reviews. They're pretty consistent for Nikon and Canon (the Pentax line seems to have been discontinued, but Pentax user sites will reflect the same). Back focusing that doesn't happen with with another manufacturer's lens.</p>

<p>Surely you're not discounting my experience are you? I'm not discounting yours. . .</p>

<p>ME</p>

<p> </p>

[laur1]

<p>Hi Vasilis,<br>

I understand that the problem that you reported was not AF specific. The thread moved into this direction based on Jim's report. The lensrentals article is discussing AF and I expect the lens specific calibration they mentioned is referring to how the lens reports its state to the body and how it responds to the commands it received from the body. The article doesn't go into technical details, but I imagined there is a calibration going on for the lens and one for the body and these are done within some tolerances.<br>

Coming back to manual focusing, this is why I asked whether you tried LV focusing on a tripod and then checking the viewfinder image sharpness (by canceling LV after achieving focus with it). Another point that was made by Jeremiah was that you could have tried the diopter adjustment to attempt to "sync" the viewfinder image. If the LV focusing didn't match the viewfinder image, then I imagine that would prove correct your theory of a misaligned sensor (as it's the only theory available :)). I'd be interested to know if such cases exist because I've often wondered whether manual focus is free from any camera calibration problems.<br>

Regarding camera industry practices - I expect it's a matter of economics - calibrating lenses and bodies within tighter tolerances would be probably too costly and you would still have the occasional mishap because the manufacturing equipment has its own tolerances, etc. It may also be that people have too high expectations of AF systems.<br>

Thanks for the confirmation about the extent of the focusing aid help. That technique of focusing then moving is not very useful when shooting at high apertures. Selecting a focusing point across the area to focus on works better, but then you need a good number of focusing points and if the area is small and moving (the eye of a kid), it becomes tricky to keep the focusing point on it.</p>

[laur1]

<p>ME said:</p>

<blockquote>

<p>Please realize that I shoot in one of the greyest places on the planet and all incoming light is appreciated.</p>

</blockquote>

<p>We're both living in WA, if I'm not mistaken - I'm in Redmond. I've been shooting a lot indoors, so my light is as poor as it can be. Because I want to keep the ISO low, I mostly shoot at f/1.4.</p>

<blockquote>

<p>Most important is the anti-blackout nature of the microprism. I've found it effective down to f 11.</p>

</blockquote>

<p>I'm not sure I understand this point - are you using preset lenses? Otherwise the focusing takes place with the lens wide open anyway. How does the aperture come into play?</p>

<blockquote>

<p>If I want something in focus closer to the frame's edge I simply move the camera that way and adjust.</p>

</blockquote>

<p>Yes, I've used this technique a lot when AFing with P&S, which have high DOF, but with SLRs, if the DOF is too thin, the movement is enough to throw the focus away. Also, I usually attempt to get pictures that are sharp even when examined at 100%.</p>

[vasilis]

<p>to Michael, I am not discounting your experience at all. A zoom lens will have a more complicated bf/ff signature because out of focus - in focus regions are affected by focal length. So any AF adjustment will not help you because it will work one end of the zoom but not the other. <br>

But what I said was not about experience, and again I am not discounting yours, it was about how the lens-camera system works. Let's leave zoom lenses aside that are more complicated and we do not undestand them maybe and think of a prime lens. The camera will decide where the lens is focusing properly, the lens does not affect this decision in any way, and then the camera will take the picture. It cannot be the lens's problem ....</p>

[personalphotos]

<p>I'm sure by now you'll ignore replying to my comments so this is just in case someone stumbles across this thread a year from now. A couple of statements require clarifications.<br>

Sorry but that's not the case. I had an FA50mm f1.4 that BF'd on 3 different bodies. The replacement (and any of my current lenses at the time) did not have this issue. It was not the body (or bodies) but the lens. I do not understand the physics and algorithms involved in focus decisions by the camera but clearly it uses contrast adjustments to make a decision on the distance to the sensor plane. Somehow the lens that is defective, tricks the AF sensors into thinking the shot is in focus. I've seen my DA*16-50mm do this on dark cloudy days when the light is flat and the scene very monotone. Users of other brands report (As with Pentax, only rarely) the same thing. So a lens has lots if not everything to do with it.</p>

<p>In fact Sigma had an issue with a few lenses about 2 years ago and asked that individual users send their lenses in directly to be "adjusted" free under warranty.</p>

<p>Second as for the split screen and central focus, DSLR's and a few upper end film bodies have given us selectable and multiple focus points. So I can hold the camera on Portrait mode and use an upper focus point on the eyes to keep the head in the top 3rd of the frame. So we are not limited to the middle spot when using an AF lens. Even an MF lens can do this if you rely on the AF points to confirm focus.</p>

[michael_elenko]

<p>Laurentiu,<br>

Good call: I do use a preset lens, a macro in fact.</p>

<p>Shooting low ISO indoors @ f 1.4 (no flash I assume) is a tough requirement. I probably would have purchased a D3 or 5D years ago.</p>

<p>And yeah, I try to get sharp images too.</p>

<p>ME</p>