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09-29-2010, 09:46 AM   #31
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QuoteOriginally posted by falconeye Quote
janneman,
you're right and I hope I wrote nothing else in the article.

The problem was that with e.g., a DA*16-50, the focus on both K-5 and K-7 was almost instant in the office-alike Pentax business area lighting (if the lens was only defocussed a bit). It was then impossible to say which one beeped or triggered faster.

Visually, I got the impression that the K-5 started to focus faster and also locked faster. Maybe, the difference I saw was significant actually. But we talk about ms differences jugded with the naked eye here. So, maybe I saw nothing.

So, a real benchmark where focus times can be measured with ms accuracy must be made. And another one in low light. And accuracy should be measured too as it is often ignored by magazine reports. AF.C is another topic. As is single image AF.S or AF.C accuracy for a moving subject...
There are very good/excellent tests conducted by the folks at "Chasseurs d'Images", a French photo magazine.
I recall having seen some tests comparing several cameras for continous AF.
Let me try to find this ... and I will be back.

Edit: Couldn't find the magazine; too messy here! I will try agaiin to post something to that effect when I have the time for proper retrieval of the article.
Anyway, those tests are exactly what you are mentioning: moving subjects in AF-C.

For me, the real difference is the AF sensor measurement integration time. It is unknown (except I saw a few bits about it in the pre-production camera EXIF fields). If this time is small, focus on fast moving subjects is possible (even if it then moves out of focus -- at least with trigger priority and maybe prediction, the result with not too thin DoF should still be usable). If this time is large, focus can't be measured because it acts as if the subject would be blurred or noisy. Like AF becomes impossible freehand at too long focal lengths or in very low light. The AF then stalls and the camera won't trigger anymore.

So, with fixed subject contrast and illumination, there should be a limit for maximum subject speed (magnification change speed actually) at which AF stops to work. If this can be measured (together with the latency between AF measurement and photo taken), we may have a good characterization of an AF system. Much more meaningful than all the common trigger latency tests (200ms vs. 300ms etc.).
Comments above embedded in text.

JP


Last edited by jpzk; 09-29-2010 at 10:04 AM.
09-29-2010, 09:50 AM - 1 Like   #32
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QuoteOriginally posted by Pål Jensen Quote
Really? My K-7 with my DA* 16-50/2.8 focus relatively slowly but the K-7 is very fast with all my screwdrive lenses....
It's relatively slow. But if you prefocus or don't change distance too much (like from 2 to 3 feet), then its speed is decent, like 1/3s. Which makes it hard to notice the AF become faster, even with a DA*16-50. And if you don't prefocus, all you measure is the SDM motor speed, i.e, the lens.
QuoteOriginally posted by jpzk Quote
Thanks for the offer, Falk.
This will likely cause my ISP to send me an error message because of the file size.
Let's just forget about it and I will continue enjoying your presentations right here!
JP, that was JohnBees offer, not mine. If he hosts the file for you in the US, it may work for you even with your under-average provider.

I know Chasseurs d'Images, it's a good magazine, maybe the best. I've a few copies despite being somewhat hard to get (its French language doesn't help ). It would be great if they would make available online a table of content of their articles (with a short synopsis) and provide full articles via paid download. A regular reader should write them a letter about. I look forward to hear about the test you mentioned.

Last edited by falconeye; 09-29-2010 at 10:08 AM.
09-29-2010, 10:26 AM   #33
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Excellent reporting. Your rep points are going through the roof and for good reason!
09-29-2010, 10:53 AM   #34
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QuoteOriginally posted by falconeye Quote
It's relatively slow. But if you prefocus or don't change distance too much (like from 2 to 3 feet), then its speed is decent, like 1/3s. Which makes it hard to notice the AF become faster, even with a DA*16-50. And if you don't prefocus, all you measure is the SDM motor speed, i.e, the lens.

JP, that was JohnBees offer, not mine. If he hosts the file for you in the US, it may work for you even with your under-average provider.
Ooops! Sorry about that.
Hope JohnB will read this .... John: apologies from me.

I know Chasseurs d'Images, it's a good magazine, maybe the best. I've a few copies despite being somewhat hard to get (its French language doesn't help ). It would be great if they would make available online a table of content of their articles (with a short synopsis) and provide full articles via paid download. A regular reader should write them a letter about. I look forward to hear about the test you mentioned.
Good idea to have this available online.
Let me check this out right away today and will be back.
Cheers.

JP


09-29-2010, 11:11 AM - 1 Like   #35
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My article on 1001noisycameras.com homepage

My article (this thread is about) made it onto 1001noisycameras.com homepage (Sep 27 issue). This is what they write:
QuoteQuote:
Detailed Pentax K-5 preview by Falk Lumo
If you prefer more detailed camera previews, instead of "unboxing" videos and camera-body touch-me pictures, you will be thrilled to know that Falk Lumo has a detailed Pentax K-5 hands-on preview from the Photokina 2010 trade show (via Rice High). This is on the Falk Lumo website, not the blog. Frankly this preview is more detailed than more than half of the "completed" reviews published at the camera review "factories"

UPDATE: Some answers to questions and additional material have been posted at the Falk Lumo blog.
[source: Detailed Pentax K-5 preview by Falk Lumo - 1001 Noisy Cameras]

Maybe, Adam acts as promised and posts his HP article too. It's maybe not in his interest that sites competing with PF are faster than him linking to a member's publication E.g., he might have preferred "via pentaxforums.com" rather than "via Rice High"
09-29-2010, 11:20 AM   #36
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will the k5 implement tethered shooting ?
09-29-2010, 11:23 AM   #37
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I checked the site "Chasseurs d'Images" (see link below)

http://www.chassimages.com/accueil/Sommaire.xml

As for your query about: "... have an online index search en table of content of their articles (with a short synopsis) and provide full articles via paid download."

You have to pay for the content; not sure how much, I haven't checked that.
So, yes they do have this feature online.

As for the actual tests they perform, it is very professionally done with standardized benchmarking, and so on.

I fail to retrieve the tests for AF-C I was talking about but when I have the time for looking into each of the magazines I have here, I will post again.
Maybe PF will have already tested the K5 for AF-C before I am able to get the info.

JP
09-29-2010, 11:53 AM   #38
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QuoteOriginally posted by pgenovese Quote
will the k5 implement tethered shooting ?
section 10.6 ... :ugh:

QuoteOriginally posted by jpzk Quote
http://www.chassimages.com/accueil/Sommaire.xml

So, yes they do have this feature online.
So, you miss an online tool too. E.g., German Heise Verlag (c't etc.) has an online keyword database to retrieve their articles (even ships on CD). Very convenient to track down that one article...

As for the sommaire. Its URL pretends to be a table of contents (this is what sommaire means). But it isn't one. It's an index of their online/forum/news articles, not their print magazine content. Only the latter is of interest though.

UPDATE:
Actually, it is possible to search for old table of content entries, up to the age of the *istD. The articles themselves however are offline. Strange ...


Last edited by falconeye; 09-29-2010 at 01:17 PM.
09-29-2010, 01:04 PM   #39
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Thanks, very interesting review!

(and I learned one annoying fact: I didn't know lcd illumination was a menu choice in the K-7. How stupid - the K10D solution is perfect )
09-29-2010, 01:50 PM   #40
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Paris' Focus Numerique cites my article

And the references to my article keep coming ...

Now, my first photo published online in Paris

Here you go: Vous prendrez bien une tranche de Pentax K-5 ? - Focus Numérique

Enjoy the link
09-29-2010, 02:09 PM   #41
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Interesting, that a few members were very disappointed about bulb mode and DFS (not being able to turn it off, that is), and somehow I don't see them jumping in joy over section 10.5.
09-29-2010, 02:15 PM   #42
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QuoteOriginally posted by Tranzistors Quote
Interesting, that a few members were very disappointed about bulb mode and DFS (not being able to turn it off, that is), and somehow I don't see them jumping in joy over section 10.5.
From Latvia, you can't see them jumping in joy in Southern California (because of earth's surface curvature, you know ...)
and while jumping in joy, they can't type either bigsmiley
09-29-2010, 02:17 PM   #43
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QuoteOriginally posted by falconeye Quote
Maybe, Adam acts as promised and posts his HP article too. It's maybe not in his interest that sites competing with PF are faster than him linking to a member's publication E.g., he might have preferred "via pentaxforums.com" rather than "via Rice High"
Maybe I spent 16 hours yesterday working on a school project, and didn't have time to post it tongue
QuoteOriginally posted by falconeye Quote
Your smilie trumps mine, I think

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09-29-2010, 02:22 PM   #44
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QuoteOriginally posted by Adam Quote
Maybe I spent 16 hours yesterday working on a school project
You're still going to school?

(Sorry, I couldn't resist -- your kids have good parents!)
09-29-2010, 11:45 PM   #45
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QuoteOriginally posted by Tranzistors Quote
Interesting, that a few members were very disappointed about bulb mode and DFS (not being able to turn it off, that is), and somehow I don't see them jumping in joy over section 10.5.

I'm jumping with joy, but very carefully and not that high since we haven't seen the final firmware yet. It does look good but things have disappeared from early firmware versions before.
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