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07-22-2009, 08:58 PM   #1
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K7 vs K10D in AF-C Focus Lag

Hi All

I am using a K10D to take images of motorcycle racing. I have built up a small business with demand now outstripping my ability to supply quality images. The main reason I don't meet demand is too many OOF images. The K10D makes awesome images when in focus, but in AF-C it will allow the shutter to release without focus lock. This is the same with the K7 I understand, but does the K7 obtain focus faster?

In AF-S the K10D just won't consistently lock on a moving image.

I am using a Sigma 70-200 f2.8II HSM lens which I believe is quite fast.

I am torn between buying the K7 which will support my significant investment in Pentax, or make the switch to a D300.

07-22-2009, 09:39 PM   #2
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Your work is high end AF dependent. While the K7 is better than the K10, I suspect the D300 is still the way to go.
07-22-2009, 09:55 PM   #3
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I was playing around with the k-7 and 50-135 in AF-C having my daughter running strait at me. The reason for this was to check the ability of the lens as opposed to the k-7, but it might help you out (or not). What I found was if I had a lock before she started running, I would get between 6 & 8 out of 10 shots with good focus (I didn't zoom in too much as it was good enough for me). If I didn't have a lock on her before she started running, it wasn't pretty. I tried this with all three options for focus points (ctr, select & multi).

I consider the 50-135 a slow focusing lens so I was kind of surprised by how well it did. You might find the 70-200 does better in terms of keeping up with a moving subject. Whether it matches the d300, I couldn't say.

Both in AF-S and AF-C, I find the focus locks faster than it ever did with my k10 (I mostly use an FA*400, a 43mm ltd and a 16-50). I also find the focus much more reliable in the k-7 over the k10. Mind you, I found the reliability of the *ist DS2 AF better than the k10, though the DS2 was MUCH slower). Lastly, the shutter lag & black-out times seem shorter in the k-7.

How the k-7 stacks up against the d300 for focus? I don't know as I haven't used a d300 for more than 5 minutes and didn't get a chance to play with the focus tracking.

Cheers.
07-22-2009, 11:34 PM   #4
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Falconeye did some extensive testing of K7 AF-C and concluded that, at least within the limits of his test, the K7 is on par with D300.

Falk Lumo: K-7 and its continuous autofocus -- PART I

Best regards,
Haakan

07-23-2009, 05:23 AM   #5
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Already with the K20, you will see improvement on this, compared to the K10. K7 should be even better.
But high-end Nikon and Canon, does more fps, and have a long reputation for AF-c

Maybe rent or borrow a K20/K7, and figure out what you wanna do. (There are a lot of Australian Pentaxians. And maybe some stores have rental programs)


Here is a thread, with more info on the subject :
https://www.pentaxforums.com/forums/pentax-news-rumors/25521-magazine-review-...good-info.html
K20 get 75% of images in focus with AF-C.
AF-C is rally the Achilles heel of the K10. I'm impressed you've managed for so long
07-23-2009, 07:34 AM   #6
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QuoteOriginally posted by flash1100 Quote
I am using a Sigma 70-200 f2.8II HSM lens which I believe is quite fast.

I am torn between buying the K7 which will support my significant investment in Pentax, or make the switch to a D300.
You will have a much higher success rate with the K-7. Now if you're going to do only sports, you maybe better with D300 which can achieve very high fps (8 with the grip AFAIK) has many AF sophistication (51 points, 3D tracking, etc.). But if it's not your main domain, and if you're a not a machine gunner, and you already a lot of investment in lenses and accessories then the K-7 is a no-brainer.
07-23-2009, 07:37 AM   #7
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If you have paying clients, get a tool that fits the job. Pentax while very very good is not the best for things like motor sports (and please, people, don't come posting nice manual focus pictures to "disprove" this). No need to fight the equipment -- its purpose is to make things easier and not be an obstacle.
07-23-2009, 08:05 AM   #8
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I'd agree w/ the "if you're getting paid" comments...if you're getting paid enough that you can drop $3K to double your successful output, get the D300 w/ the Nikon 70-200VR. That lens is much faster than the Sigma as well.
The K7 will probably be a big step up, but again, if you're making a nice profit, get the best tools for the job and focus on selling for more profit ;-)

07-23-2009, 08:28 AM   #9
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Yup, increase your income enough and you can afford to have the D300 for shooting your work and a K7 with all the lenses for fun.
07-23-2009, 12:42 PM   #10
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My suggestion would be to buy the K-7 from a place with a good return policy, or maybe even rent one. Try it for a couple days with a few controled tests and see how it feels to you.

Better yet, rent both the K-7 and the Nikon at the same time and put them both through the wringer. The Nikon may very well be a better performer, but that doesn't mean it will work for you. There is much to be said about the subjective side of the calculation.
07-24-2009, 04:57 AM   #11
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Had a play with a K7 today. I am very surprised by the size (small) compared to my K10D + grip. Did a basic seat of the pants test where I compared the K10D focus speed in AF-S using a Sigma 70-200 f2.8II HSM on both cameras. Setting the cameras to identical settings and the lenses to identical settings (manually set the focus distance to as short as possible while shooting at a wall about 10 meters away).

Pressing the shutter release half way to achieve focus, the K10D ranged between 1.5 and 4 seconds to lock focus (on one test it would not lock at all!). The K7 was consistent, essentially it took as long as the lens took to spin to achieve focus - around 1 second. Agree the test is basic - I did it about 30 times on each camera so I'm fairly happy that the results I got are somewhat representative.

Played with a DA 50-135 too. Can't believe how light it is! Interestingly focus tiime on the K7 "appeared" to be slightly slower than the Sigma, but differences in time to lock focus between the K10D and K7 were similar.

A local dealer here has arranged a Pentax day on Sunday to play with the K7 and Pentax and Sigma lenses. I am going along to have a more extensive play and test, but first impressions are quite good
07-24-2009, 03:19 PM   #12
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QuoteOriginally posted by flash1100 Quote
Had a play with a K7 today. I am very surprised by the size (small) compared to my K10D + grip. Did a basic seat of the pants test where I compared the K10D focus speed in AF-S using a Sigma 70-200 f2.8II HSM on both cameras. Setting the cameras to identical settings and the lenses to identical settings (manually set the focus distance to as short as possible while shooting at a wall about 10 meters away).

Pressing the shutter release half way to achieve focus, the K10D ranged between 1.5 and 4 seconds to lock focus (on one test it would not lock at all!). The K7 was consistent, essentially it took as long as the lens took to spin to achieve focus - around 1 second. Agree the test is basic - I did it about 30 times on each camera so I'm fairly happy that the results I got are somewhat representative.

Played with a DA 50-135 too. Can't believe how light it is! Interestingly focus tiime on the K7 "appeared" to be slightly slower than the Sigma, but differences in time to lock focus between the K10D and K7 were similar.

A local dealer here has arranged a Pentax day on Sunday to play with the K7 and Pentax and Sigma lenses. I am going along to have a more extensive play and test, but first impressions are quite good
Good to hear, let us know how your Pentax day goes.

Maybe your Sigma is faster than the DA* 50-135, if the Sigma has true ring-type Hyper Sonic Motor. Where the Pentax use the slower micro sonic system.
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