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05-21-2009, 09:07 AM   #16
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Sounds like the greatest gain would have to be in the SDM lenses, so it'd pay to have a line up of them with the K-7....

Mo' money!

05-21-2009, 09:18 AM   #17
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..
EDIT: i was wrong.

Last edited by blende8; 05-21-2009 at 09:27 AM.
05-21-2009, 10:13 AM   #18
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QuoteOriginally posted by dnaseigel Quote
Last Friday our Pentax sales rep brought a K-7 to our store for us to see and comment on. He brought it with a 21 Limited and the size and feel was fantastic. Anyone who is fearing this camera is going to be too small, please do no worry. The ergonomic planning on this camera is our of this world.

The thing that I noticed immediately was that the auto focus was not conspicuously faster than the K20D which I viewed side by side with the K-7. However when I put the DA* lenses on, and I put all six of them on, I was startled by the difference in AF speed. The biggest difference was in the 55mm f/1.4 and the 300mm f/4. However all the DA* lenses focused much more responsively than they did on the K20D.

It was also encouraging to see it lock focus on very low contrast subjects. I am of the opinion now, even just test driving a pre-production model, that this is the speed merchant camera that Pentax enthusiasts have been waiting for.

Speeking of waiting, it has been a nightmare keeping my mouth shut so as not to violate our NDA. This camera will prove to be well worth the wait, and I submit now that it will dwarf the attention the K10D brought to Pentax.

Peace
After reading as much as I can find on the K7 specs, I came to the conclusion that many could be in for a disappointment in the AF area. Your post sort of adds some evidence that I might be right about this.

First of all, there is a lot of confusion over the mention of 2 AF systems in the camera and specualtaion that this is referring to the sensor that detects the light wavelength and then offsets the AF accordingly.

I think that the 2 AF system reference has nothing to do with the wavelength adjustment feature, but instead refers to the new contrast detection AF process (used solely for Live View when the mirror is up, if I am correct), and the AF system used for still photography (when the mirror is down). The mirror-down AF system really isn't significantly different than what is contained in the K20D (if I am right here) but perhaps has the improved algorithms developed for the newer Pentax bodies released since the K20D.

Take note of the description of the K7 AF system having 11 points and so on. Sounds familiar, right? That's because it likely is basically the same phase detection sort of arrangement that is found in the K10D and the K20D, albeit with (hopefully) improved controlling software, and maybe some other tweaks to improve speed, along with the addition of the color sensor to improve accuracy in tungsten and FL lighting.

I am not by any means a Pentax basher, but I suspect that the AF performance of the K7 will not be a night and day sort of improvement and that will make many folks unhappy.

Ray
05-21-2009, 10:20 AM   #19
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QuoteOriginally posted by Ray Pulley Quote

Take note of the description of the K7 AF system having 11 points and so on. Sounds familiar, right? That's because it likely is basically the same phase detection sort of arrangement that is found in the K10D and the K20D, albeit with (hopefully) improved controlling software, and maybe some other tweaks to improve speed, along with the addition of the color sensor to improve accuracy in tungsten and FL lighting.
Yeah, the fact that it didn't even merit a new revision number (SAFOX VII to SAFOX VII+) has me wondering how much of an update it really is.

But I do hope it'll be a positive surprise. This camera really could be everything people wanted the K20D to be (short of being FF ). The color sensor sounds like a nice upgrade!

05-21-2009, 11:04 AM   #20
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Ray, in LiveView/Video, Contrast AF is done Via main sensor, nothing else.

So, yes, the second AF sensor is used for phase detect AF.
05-21-2009, 11:23 AM   #21
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As I understand it, it's both algorithmically better (think K-m) and also better because the camera now knows what sort of light is coming in and can adjust for it. That likely leads to better AF consistency in different light temperatures, and possibly across the board too.
05-21-2009, 11:25 AM   #22
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The press release states:
"The K-7’s new SAFOX VIII+ wide-frame autofocus system features 11 sensor points (with nine cross-type sensors positioned in the middle). By adding a light source type to its data range, and driven by a greatly improved algorithm, this AF system assures reliable, responsive autofocus operation superior in speed and accuracy to the previous system."

How do you think this is realized?
05-21-2009, 11:31 AM   #23
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QuoteOriginally posted by wll Quote
Nikon D90 ?????

Don't you mean how it stackes up to the Nikon D300 or the Canon 50D ?


wll

Before it beats the D300 it has to beat the D90, and from what I've read so far about the AF improvements, I'm not sure it will - I'm hopeful, but not certain.

My D90 beats my K20D in AF-lock speed hands-down in any lighting situation. We need the K-7 to match the D90 if possible - it may be too much to ask for it to match the D300 (especially with grip.)


.

05-21-2009, 11:43 AM   #24
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For what it is worth I have been very dissapointed with the initial speed of the DA*300/f4 on my K20D bodies in finding the subject and following fast ones. It some times does not even want to start up when the camera is turned on. I have gone back to my FA* 300/F4.5 for wing shooting birds because of it.

If there is a noticable improvement with the K-7 using the DA*300/f4 that would be very welcome.
05-21-2009, 11:55 AM   #25
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Frankly, I think it's hard to compare: after all, AF speed seems an anecdotal matter and observations at the counter certainly don't seem much of a judge... as for a d90, well, a camera that doesn't do what I need more rapidly than something which does, isn't much of a basis, either.

I'm in the camp of wanting accuracy more than speed, anyway. With a D90, you can't even meter with (or on occasion *have*) older lenses that'll go with a film body, so I find a lot of it theoretical, anyway. If it's really the lens holding a body back, well, it's the lens.

Could be good news about that 55, though: if I want something brand new that'll perform well in that way, that's it.
05-21-2009, 11:58 AM   #26
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QuoteOriginally posted by blende8 Quote
The press release states:
"The K-7’s new SAFOX VIII+ wide-frame autofocus system features 11 sensor points (with nine cross-type sensors positioned in the middle). By adding a light source type to its data range, and driven by a greatly improved algorithm, this AF system assures reliable, responsive autofocus operation superior in speed and accuracy to the previous system."

How do you think this is realized?
Well, it IS a marketing release and has no specificity or data to back up the claims, so what does this statement really mean?

We know what the light source sensor does, and frankly I would be hard-pressed to believe that adding a sensor that has to be read and processed and then taking that data and using it to adjust the AF would make the whole process FASTER. After all, in the K20D no such sensor/calculation was included.

More accurate in certain lighting, yes, as that is what it is designed to do, but Faster, no. This part has nothing to do with speed improvements.

That leaves us with unspecified improvements to software and perhaps changes to the hardware that are not known to us or even mentioned.

So, if one takes the press release as the source, we are left mainly with claims about software improvements, which I am sure are true, but to what extent?

How do algorithms improve low-light focus speed?

I also do not see any mention of anything new in continuous AF or in predictive AF capabilities, although improving the speed of the overall system should also improve the ability to continuously focus even if it is not a true predictive system.

Time will tell.

Ray
05-21-2009, 11:59 AM   #27
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QuoteOriginally posted by jsherman999 Quote
Before it beats the D300 it has to beat the D90, and from what I've read so far about the AF improvements, I'm not sure it will - I'm hopeful, but not certain.

My D90 beats my K20D in AF-lock speed hands-down in any lighting situation. We need the K-7 to match the D90 if possible - it may be too much to ask for it to match the D300 (especially with grip.)


.
I'd be interested in seeing the results of a controlled test on that. I'm not sure the best way to set it up, but I'd want to see a test that both timed focus to shutter AND focus accuracy.
05-21-2009, 12:01 PM   #28
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QuoteOriginally posted by thibs Quote
Ray, in LiveView/Video, Contrast AF is done Via main sensor, nothing else.

So, yes, the second AF sensor is used for phase detect AF.
Hence SAFOX VIII+

Ray
05-21-2009, 12:09 PM   #29
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I'd think that 'adding a light source to its data range' means that the AF is now sensitive to more wavelengths: Wavelengths being what 'phase-detection' *detects,* that's potentially a big deal. You get more data processed faster, (with new algorithms and processor speed, apparently) ...so, in theory, you get faster and more accurate AF.
05-21-2009, 12:24 PM   #30
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QuoteOriginally posted by Ray Pulley Quote
First of all, there is a lot of confusion over the mention of 2 AF systems in the camera and specualtaion that this is referring to the sensor that detects the light wavelength and then offsets the AF accordingly.

I think that the 2 AF system reference has nothing to do with the wavelength adjustment feature, but instead refers to the new contrast detection AF process (used solely for Live View when the mirror is up, if I am correct), and the AF system used for still photography (when the mirror is down). The mirror-down AF system really isn't significantly different than what is contained in the K20D (if I am right here) but perhaps has the improved algorithms developed for the newer Pentax bodies released since the K20D.
Sorry, this is flat out incorrect. There is no speculation that the 2nd sensor detects light wavelength. This is established fact straight from the horse's mouth. The 2nd sensor compensates for lighting type (tungsten, fluorescent, etc.). If you haven't watched the K-7 intro video on Youtube already, definitely check it out.

But you're right that this should have no bearing on speed, but rather on accuracy. Speed improvements should come from whatever mojo they put into the K-m. According to people who have tested it side-by-side with other Pentax cams, the K-m is significantly faster at AF than older cameras, which has nothing to do with less AF points because it's also faster when the compared cameras are both just using 1 point.
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