tag:blogger.com,1999:blog-2599082310926453927.post2168679810737199970..comments2024-02-26T14:48:08.264+01:00Comments on Falk Lumo: LumoLabs: Pentax K-5 low light focusFalk Lumohttp://www.blogger.com/profile/00476649880132648032noreply@blogger.comBlogger45125tag:blogger.com,1999:blog-2599082310926453927.post-15286814692793074362012-06-29T13:44:49.932+02:002012-06-29T13:44:49.932+02:00I know about the fnac test. I'm a Pentax user ...I know about the fnac test. I'm a Pentax user for a long time, an I'm only saying that the improvements are no enough to compete with, for example, Nikon D300. There are lot of people asking for a brand new af system. Thats all what I said. Accept it or not, but thats is the reality. Thank you.Torrenteshttps://www.blogger.com/profile/02480392464741210122noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-35097110641809382542012-06-29T13:04:38.908+02:002012-06-29T13:04:38.908+02:00@Anonymous, your statements are basically wrong wi...@Anonymous, your statements are basically wrong with only a small core of truth. E.g., you may look at various editions of FNAC (France) test magazine and see how much the Pentax AF performance (both AF.S and AF.C) improved over generations. In two more recent tests, the K-5 has beaten all competitor AF on accuracy. The K-5 AF is considered by most to be on par with the Nikon D7000 AF which means that it isn't yet in one league with Nikon D300 or D4.<br /><br />I agree, there is room for improvement and this article deals with one: the problem with very low light when the light color isn't measured accurately anymore.<br /><br />Your unspecific criticism really goes too far and I will not accept further comments from your part. Thanks for understanding.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-38006116427425572772012-06-28T23:41:21.049+02:002012-06-28T23:41:21.049+02:00Pentax hasn't made yet any improvement in the ...Pentax hasn't made yet any improvement in the AF module since its launch in the *ist camera back in 2003 (19 years with the same in the af module!!!!). You can see in the following link the patent http://www.freepatentsonline.com/6937818.html<br />The AF sensor are designed to work accurately when f-number is 5,6 or smaller (8,11, etc.) but when we try to take a picture at, let's say 2.8, our troubles start, specially if the focus is close, because depth of field is really narrow.<br />The problem is really big if we are using large apertures and light with a warm color temperature.<br />Is there a solution? Well IMHO, it could be fixed with a better color temperature detection system , aka, auto white balance.<br />Pentax needs to design a new and better af module that works accurately at 2.8 apertures and more than 11 focus points. SAFOX VIII to IX+ are basically the same. There are only minimal software improvements between them.<br />SAFOX IX+ is IMHO obsolete for a long time, could be a decent af system for a entry level dslr, but not for a flagship model.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-3109443481398887462012-03-06T11:27:37.402+01:002012-03-06T11:27:37.402+01:00I don't think so. When the issue was first rep...I don't think so. When the issue was first reported with the K-5, this was examined and it was found that IR cut filters don't alter the effect. However, I did not study this myself.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-66399727877246516052012-03-05T21:44:53.301+01:002012-03-05T21:44:53.301+01:00Do you think the infra red could be rsponsabile fo...Do you think the infra red could be rsponsabile for it (see also http://ricehigh.blogspot.com/2011/12/deepere-technical-investigation-into-k_16.html)Bogdannoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-70268988323202559682012-03-05T11:27:58.566+01:002012-03-05T11:27:58.566+01:00No news I am aware of.No news I am aware of.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-55554173984781415272012-03-05T09:40:59.616+01:002012-03-05T09:40:59.616+01:00Any news, any hopes of improvement from Pentax?Any news, any hopes of improvement from Pentax?Bogdannoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-50280129809917191682011-12-19T09:58:01.256+01:002011-12-19T09:58:01.256+01:00@Andrew: I am unaware about such a thing and haven...@Andrew: I am unaware about such a thing and haven't seen any evidence for such an effect. Sensor shift SR and phase AF should be independent things. However, SR should improve contrast AF in low light a lot and w/o applying any patent. And there is a patent where the phase AF module sits on its own shift motor. The reason why SR helps with contrast AF is that contrast AF w/o SR would have to work on blurred images in low light (i.e., contrast would be random and never be high). Pentax SR is active during contrast AF :)Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-67106933479987686932011-12-19T01:07:23.427+01:002011-12-19T01:07:23.427+01:00Is there any evidence that SR could improve autofo...Is there any evidence that SR could improve autofocus accuracy in low light? I read about a patent somewhere stating that SR assists autofocus.Andrew Richardsonhttp://www.flickr.com/photos/andrewdalerichardson/noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-9098817835450565622011-09-22T08:06:35.173+02:002011-09-22T08:06:35.173+02:00I have acquired yesterday a k-5 and observed immed...I have acquired yesterday a k-5 and observed immediately the focus problem in low light, compared to a pentax k-x which works great. Now I'm going back to the shop to return the k-5. That focus problem is not acceptable in my opinion.Sorinhttps://www.blogger.com/profile/09328151618391207033noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-52453149542778635842011-08-03T11:54:03.459+02:002011-08-03T11:54:03.459+02:00I wanted to thank you for this great read!! I defi...I wanted to thank you for this great read!! I definitely enjoying every little bit of it I have you bookmarked to check out new stuff you post.<br /><a href="http://www.ukdigitalcameras.co.uk/digital-slr/" rel="nofollow">Digital SLR Cameras</a>Johnhttps://www.blogger.com/profile/01146312241821970338noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-78701152113386363922011-08-03T11:50:01.596+02:002011-08-03T11:50:01.596+02:00I wanted to thank you for this great read!! I defi...I wanted to thank you for this great read!! I definitely enjoying every little bit of it I have you bookmarked to check out new stuff you post.<br /><a href="http://www.ukdigitalcameras.co.uk/digital-slr/" rel="nofollow">Digital SLR Cameras</a>Digital SLR Camerashttp://www.ukdigitalcameras.co.uk/digital-slr/noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-15222057115267520622011-07-29T12:18:28.037+02:002011-07-29T12:18:28.037+02:00Thank you for your time to share this excellent an...Thank you for your time to share this excellent and informative post. It 's my first time, during my visit here. I found a lot of material in your article. Keep it up. Thanks.<br /><a href="http://www.ukdigitalcameras.co.uk/digital-cameras/canon-digital-cameras/" rel="nofollow">Digital Cameras Canon</a>Digital Cameras Canonhttp://www.ukdigitalcameras.co.uk/digital-cameras/canon-digital-cameras/noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-31071255164900812272011-06-11T22:48:35.215+02:002011-06-11T22:48:35.215+02:00@Anonymous, you should take into account that the ...@Anonymous, you should take into account that the AF tries to make defocus zero. It accepts less perfect focus for low light but defocus will NOT measure the front focus issue. Otherwise, it wouldn't exist in the first place. Moreover, I didn't study the effect of small defocus or its sign.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-2227436593919143572011-06-11T20:21:58.747+02:002011-06-11T20:21:58.747+02:00I'm very surprised that you found no correlati...I'm very surprised that you found no correlation between AF Predictor and your optical measure of defocus<br />AF Predictor seems to give the amount of defocus (positive value for a BF, negative for FF) as measured by the AF sensor<br />You should at least observe, in normal conditions, a correlation between the sign of the AF Predictor and the sign of your df indicatorAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-54849527609339328172011-06-11T19:40:16.157+02:002011-06-11T19:40:16.157+02:00@Anonymous, yes, I looked at correlation between d...@Anonymous, yes, I looked at correlation between defocus and AF integration time, AF predictor and AF defocus. But I found no strong correlation. All values go up if it gets darker and AF integration time maxes out at 255 ms or so. It is mostly at these max. AF integration times (but not always) that the front focus issue shows.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-14896328218091333452011-06-11T11:52:21.758+02:002011-06-11T11:52:21.758+02:00Hello
Thank you for your very interesting study
N...Hello<br /><br />Thank you for your very interesting study<br />Now you have defined way to optically measure defocus, have you tried to compare these measures with the AFPredictor values (Defocus measure from AF sensor point of view?) present in Exif data?<br />I would be very interested to know about the correlation between these 2 valuesAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-65520764829044097882011-05-26T17:43:45.601+02:002011-05-26T17:43:45.601+02:00Thank you for your analisys of the problem, I have...Thank you for your analisys of the problem, I have a K7 that also frontfocuses in low, tungsten light (but contrast-detect focus is spot-on).<br />I've always wondered why K7's AF-assist is green while those mounted on "legacy" flashlights and on camera from other manufactures is red/orange.<br />I came to the conclusion that my autofocus simply hates low, warm lights... and that's a pity since AW-balance is good.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-83253213807533182792011-05-23T23:49:16.650+02:002011-05-23T23:49:16.650+02:00@Anonymous: The EV values I am quoting are explain...@Anonymous: The EV values I am quoting are explained in ample detail within the report. I don't consider EV values as obtained by a camera's meter to be accurate enough. They are accurate for daylight and an 18% gray target which turns out mid gray in sRGB. In all other cases one has to apply corrections.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-91851379754969020772011-05-23T21:05:44.171+02:002011-05-23T21:05:44.171+02:00Hi
"Slower lenses can already start to front...Hi<br /><br />"Slower lenses can already start to front focus at light levels metering as 4 EV or 6 EV even. A fast lens may work down to 0 EV in white light."<br /><br />Just to confirm after glancing at your blog entry and your report. Are the EV figures quoted above 'exposure EV values'?<br /><br />We just bought a K5 a couple of days ago and immediately noticed frequent front focus with our fast f/1.4 50mm Pentax lens. Initially we played around with the AF fine adjustment and then came across your blog entry.<br /><br />Just trying to correlate our experience in terms of front focus with our 'exposure EV' values with the values you quote.<br /><br />ThanksAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-7819310120560123722011-03-29T07:09:19.060+02:002011-03-29T07:09:19.060+02:00For anybody watching the comments here: I publishe...For anybody watching the comments here: I published another blog article to look at the improvements brought by the v1.03 firmware.<br /><br />As for the comments above about market aspects: Let me make myself clear: I consider the K-5 to be the best APS-C camera today. All aspects combined. But Pentax really could make it a bigger hit if it reacted quicker to user feedback.Falk Lumohttps://www.blogger.com/profile/00476649880132648032noreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-24578951494677297142011-03-27T21:07:12.486+02:002011-03-27T21:07:12.486+02:00Disagree. The K-5 has certainly received a lot of ...Disagree. The K-5 has certainly received a lot of well-deserved accolades, but as far as interest from consumers....the K-x, from the entry-level point of view, was a big success. The combination of great reviews, low price, excellent high ISO results (rivaling even some full frame cameras), and some radical color choices (esp. for DSLR) really helped Pentax become a viable option for beginner DSLR owners. <br /><br />For the first half of 2010 it was #6 in all DSLR sales. The Nikon D5000 with its articulating LCD was #3 and the omnipresent Canon 550D was #4). Considering Nikon and Canon dominate the advertising market, it's a pretty decent showing for a relatively niche company like Pentax.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-91601847038361268062011-03-27T19:08:02.715+02:002011-03-27T19:08:02.715+02:00When I was young Pentax were as popular as Canon (...When I was young Pentax were as popular as Canon (Nikon was then much more expensive than either of these brands), but not until the K-5 the Pentax brand has again gotten major interest from the consumers.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-30654229514935188512011-03-19T23:17:54.308+01:002011-03-19T23:17:54.308+01:00Just an observation about why there are so many Ca...Just an observation about why there are so many Canon and Nikon (esp. DLSR) users. It is my sense the high rate of Canon and Nikon users primarily stems from the coattails of popularity. Many people assume something is good if it is popular. This notion stands to reason at many levels, but could also be attributed to a simple desire to own something that is perceived to be "better" than another brand. And a lot of people tend to follow this perception with the least amount of toil required. In other words, they would rather just buy a camera that is popular than look into any comparisons on a more detailed level. And if you look at Pentax there are plenty of reasons to buy their products instead, and while their sales are improving....they still lag behind the Canon/Nikon juggernaut. The aggressive marketing advantage Canon and Nikon enjoy (wisely) also contributes to their success....and this aligns perfectly with the popularity notions I mention. As Falk stated Pentax started off very slow and are trying to catch up....so it's ironic that Pentax was the leader in film SLR's for many years. <br /><br />That's not to say Canon and Nikon don't make great cameras. They do. And a lot of professionals won't use anything else for a variety of reasons having nothing to do with popularity. But Pentax is making strong inroads toward their relative monopoly (and Sony and Panasonic are bridging the gap with their strong mirrorless approaches) and I can foresee the day when there is more of a competitive balance (a parity that can actually be good for Canon and Nikon users)....though one would expect much of that hinging on Pentax and their marketing ideas (even though I like that they think about the cameras and the photographers who use them more than slick advertising). <br /><br />In short, Pentax is the red-headed stepchild (as Seinfeld would say "not that there's anything wrong with that"), but the child is growing up and learning from their years of "therapy". Don't be surprised to see the kid become President someday.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2599082310926453927.post-66607828692591949752011-03-19T22:17:00.633+01:002011-03-19T22:17:00.633+01:00Great Work!
One question however. I understand tha...Great Work!<br />One question however. I understand that It can be expected to see cameras front focus in tungsten. But why some of those new Nikons D7000 shift to back focus in tungsten? Do you care to investigate?Anonymousnoreply@blogger.com