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Old Dec 13, 2007, 6:46 PM   #21
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lol

Unfortunately, the manufacturers are getting pretty stingy on letting reviewers keep gear for long anymore. Steve's DSLR-A700 went back weeks ago.

Besides, if he was able to convince Sony to let him keep one for a "long term" evaluation, I think I'd be lobbying to let me have it for that purpose. lol

I only bought the a700 body (with no new lenses), and I was still in the doghouse for a few days. My wife just doesn't understand it when she checks the bank account and notices money gone and I admit I spent it on a camera. "Don't you already have cameras!?" :-)

Sony really should try to sponser more shooters though. Canon and Nikon are good at that kind of thing. Sony will need to learn how.

You've got my vote if you can convince Sony it would be a good idea to give you some gear to test. It probably wouldn't be a bad idea. You shoot lots of sports, and they really need to get more exposure in this area for the Alpha system.

Also, because you're shooting mostly high school sports, conditions are not going to be as nice, and you'd be pushing the limits of the equipment more.

In addition, I think the potential buyers of their current advanced amateur model (a700) would probably identify more with a camera model that could be used for shooting high school level sports.

Unfortunately, my vote probably wouldn't get you very far. lol

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Old Dec 13, 2007, 6:48 PM   #22
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I don't know about you guys but the above certified results from Pop Photo are very telling...

In the worst case if the AF has to be re-acquired every frame, the Sony camera is the most likely to meet it, since 1/240ms is about 4-5 fps - Correct?

-> How in the heck can the 1D MrkIII refocus in 100ms (i.e. @ 10fps) when it takes at least 330ms to get a lock when the subject is totally out of focus between frame? Granted tracking will require only smaller steps, but if a subject falls out of an AF point entirely and the camera needs to get back on it'll take longer than 100ms - Remember you're shooting in shutter priority here with a burst? :?
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Old Dec 13, 2007, 7:06 PM   #23
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Maybe not.

Most of those focus tests are designed so that you're focusing from scratch, versus a focus distance that's close to the last time the camera locked.

Even if a camera loses focus during tracking, very little movement of the optical groups for focusing may be required for a new lock , since the focus distance hasn't changed much from the last lock (unless it tries to lock on the background instead). lol

That should be much faster compared to the way they would probably test them (making sure the lens is not focused anywhere near the correct focus distance when they start timing it).

Once you get an initial lock (unless the camera decides it can't find the target and needs to hunt over a wider range), the mechanical aspect of it would probably play a smaller role, and the speed of the algorithms would probably play a larger role.

That's one theory anyway. lol I'm sure the engineers know for sure. That's one reason I couldn't help but wonder if the new user definable focus parameters in models like the EOS-1D Mark III could be playing a larger role than people may think (processing speed may be more critical than the speed of the focus motors, etc., once a lock is acquired, since not much movement should be required to maintain focus).

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Old Dec 13, 2007, 9:49 PM   #24
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JimC wrote:
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Even if a camera loses focus during tracking, very little movement of the optical groups for focusing may be required for a new lock , since the focus distance hasn't changed much from the last lock (unless it tries to lock on the background instead). lol
I agree - That why I said "In the worst case if the AF has to be re-acquired every frame" and "Granted tracking will require only smaller steps, but if a subject falls out of an AF point entirely..."

-> But remember we're talking about a moving subject which is not staying still for the AF point to work on, beside the contrast also plays a big role beside good lighting like a "sunny" day... (the AF point could land on a blank part of the jersey for example)



Quote:
... very little movement of the optical groups for focusing may be required for a new lock...
Yeah - but doesn't this hold true to every camera in tracking, be it Oly or Canon? :idea:
-> while other camera may have up to 200ms (5fps) to perform this little adjustment in optics, the 1DmrkIII has to do it in 1/2 the time (i.e. 100ms) to keep up its frame rate; However, according to the initial lock result the MrkIII AF algorithm is not any faster, but actually slower (down to EV-4 like on the Sony)!!!
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Old Dec 13, 2007, 10:39 PM   #25
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And yet all theory asside, the mkIII performs wonderfully at 10 frames per second. And, out in the field where it matters most.

Of course the photographer still has to do their part and keep the point on the subject. And they still have to keep it on a contrast point. Although I've found the mkIII works much better on low contrast areas than my 20d did. Still - it's another reason why action shooting isn't as easy as people think it is. Like so many other aspects of photography, you still need a skilled photographer to get the job done. No matter how good a camera a manufacturer makes, people will still be able to take lousy pictures with it :G

But you also have the option of enabling assist points if you're not skilled enough yet (in sports) or if your subject is very eratic (small birds).

So in the end, I'm happy with my 'slower' autofocus which somehow provides me a FASTER 10 fps - maybe the initial lock takes extra miliseconds but it's a small price to pay to have the reduced time between frames that 10fps provides over 5.

But again it's apples and oranges - the mkIII is a pro body and the others in this discussion are not. When the D3 gets rolling it will be interesting to see how the two compare.


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Old Dec 13, 2007, 11:16 PM   #26
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JohnG wrote:
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But again it's apples and oranges - the mkIII is a pro body and the others in this discussion are not. When the D3 gets rolling it will be interesting to see how the two compare.
IMO it'll be no different... :-)

The D3 manual (like the MrkIII) already said so in AF-C mode (page 304): "Photos can be taken even when the camera is not in focus..."
http://www.nikonusa.com/pdf/manuals/...en_noprint.pdf

Whenever you're shooting faster than a camera can track the probability of out of focus frames is always there!
-> That's not to say when there's little to no tracking between frames, 100% focus can be achieved, but again most cameras can do that too...
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Old Dec 14, 2007, 11:16 PM   #27
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Ah, but that's the beauty of technology. At 10 fps, even ifI wasgetting a poor keeper rate of 60% that' s 6 in focus frames a second.

How many times a second can you press the shutter in one-shot:-):-)

And even in one shot there's no guarantee of perfect focus - forums are full of soft images from people using one shot.
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Old Dec 15, 2007, 9:14 AM   #28
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JohnG wrote:
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Ah, but that's the beauty of technology. At 10 fps, even ifI wasgetting a poor keeper rate of 60% that' s 6 in focus frames a second.
... and that's the way any camera should work in the burst mode!
IMO there's nothing wrong with this MRkIII and all this AF issue is just a red herring - Even the camera manual says so: When "Drive speed priority" is selected, the focusing might be slightly off, but the shooting speed will be fixed.

-> Some one just decided to arbitrarily compare it to a MrkII in a narrow set of circumstances. What about others? I'm not knocking the MrkIII in anyway - Check all my posts - In fact I'm actually defending it:
http://forums.steves-digicams.com/fo...=37&page=1




Quote:
How many times a second can you press the shutter in one-shot:-) :-)
All I need is one shot even if it takes me 365 days to do it :lol::-):G
-> This where we differ...
Photography is, at least, for me to relax and to take time to enjoy nature. If I miss a shot I'll gladly go back to the same spot on my next vacation to relive the things I've missed. One of my car for example can do 0-60 in less than 5s, but how many time do I time myself? I enjoy the build, the handling, and the ergonomis instead, and rather take the long road and relax after a long work (not in photography) week!
This is not to say that I don't use the high-frame rates nor the 45 AF points on my 1D when needed. In fact my field is technical and I do appreciate all the innovations Canon's have put in their design, but frame rates sit very low on my list of priority (or high-ISO for that matter)...




Quote:
And even in one shot there's no guarantee of perfect focus - forums are full of soft images from people using one shot.
Haven't we been here before? :?

o One-shot AF does not guarantee perfect focus, but it is always stop spot on an AF point (or points) which was lit up when that one shot was released - Correct?

o AI-servo on the other hand does not stop focusing and no AF point is lit up - Correct?
-> If you notice the lens dither back and forth in AI-servo to anticipate the movements so if you take a single shot in this mode with a very narrow DOF lens like a fast tele prime, that single image will fall into three categories: In focus, front or back focus: http://forums.steves-digicams.com/fo...19&quote=1
" When I have my Mark II on a tripod, with a 400mm f2.8 lens focused on a brick wall, with a single focus spot, AI Servo, the lens twitches. The lens is constantlly making small adjustments. Basically from a soft image to a sharp image. As I described the platform is stable and the subject is stable, so it is not a camera or subject movement problem."
"It is normal for the camera to hunt when AI servo mode is used to acquire focus on a stationary object. One-shot mode should be used to focus in this situation. In AI Servo AF, the camera continuously samples the AF detection data at varying rates of frequency depending on the light level"
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Old Dec 15, 2007, 10:09 AM   #29
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And even in one shot there's no guarantee of perfect focus - forums are full of soft images from people using one shot.

Here again. How many of them were using a lighter lens. I definitely dont rely on single point AF with a heavylens and when i am holding it in my hands. Invariably my body is tilting forward and backward. And some times i end up getting imgaes that are OOF though i heard the AF Beep confirming a lock. I feel using the big lens in shorter focal length is exactly similar to using a macro lens. Or atleast comparable. Any movement of the body translates to OOF image. And i have got more keepers using the AI-Servo when having a heavier lens mounted

The OOF Images these people have displayed are either 150% zoomed and u just see a face meaning that at that magnification unless its a macro one is not going to see exceptionally sharp image. Some post claiming soft focus in Single shot in other forums didnt even have images that were filling the entire frame.

I am not sure how others feel, but i defnitely feel a more subjective testing would be to fll the frame and take 100%.

here is one with single point af handheld using the 500mm at 500mm F4. I am starting to use this lens more for portraits... straight from the camera with default 2 sharpening.
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Old Dec 15, 2007, 11:12 AM   #30
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NHL wrote:
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o One-shot AF does not guarantee perfect focus, but it is always stop spot on an AF point (or points) which was lit up when that one shot was released - Correct?
Technically true. But servo locks on a focus point as well. You still have the same issue of contrast. So having that single focus point in a low contrast area the camera may THINK it's got focus but the focus will still be off. All one shot guarantees is that the camera will wait until it THINKS it's got a lock. But the focus distance it calculates isn't always accurate. Again, think of all the soft focused portrait shots out there - think the photog completely missed their subject with a focus point? It still takes good focus technique even in one-shot.

I get just as many first shot keepers in ai-servo as in one shot because the technique is the same. Ai-servo is just a tool. When you learn how to use it it works just fine. Just like any other tool. It's like a manual transmission - if you know how to use one it can work better than an automatic transmission.

As for different styles - I completely agree. Unfortunately for my photography I can't afford to miss the shot and come back. And with a 16 month old son I somehow don't have the same amount of free time to return to the scene for another try even if I wanted to:-)

Enjoy the weekend!
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