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Old Jun 18, 2009, 10:39 AM   #21
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Finding m4/3 lenses for sale in France is virtually impossible. Until there are more on the market, its not a format that I'd look into.

The E-620 is leading.
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Old Jul 22, 2009, 3:23 PM   #22
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On the usefulness of the live view: Do you guys (w/o live view), when using a tripod and long shutter speeds, put the eyepiece cover every time on the viewfinder to block light entering it?

IMO, this is a major PITA. I use the viewfinder to "setup," switch to live view which automatically closes the viewfinder, and that's it.

I am not familiar with other DSLRs, but on the a300, you have to remove (slide up) the viewfinder eye cup to put the eyepiece cover on, which is very annoying / time consuming.

With the Sony a300, the live view, like mentioned on the Sony models, is just as fast as any AF DLSR.
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Old Jul 22, 2009, 4:52 PM   #23
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It's unlikely that most dSLR users even realize that light entering from the viewfinder can impact the camera's metering. You're ahead of most if you know a viewfinder cover is usually a good idea.

Ideally, you'd block light entering through the viewfinder to insure more accurate exposure. But, you could always compensate (if needed) with most camera models if you didn't block that light.
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Old Sep 8, 2009, 11:31 PM   #24
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Default slow AF in live view mode - why?

I was surprised to learn that live-view makes AF so slow on the Nikon and Canon DSLRs; why is this so?
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Old Sep 9, 2009, 6:50 PM   #25
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Quote:
Originally Posted by JimC View Post
You'll find some precise AF timings for them at Dave Etchells' site (imaging-resource.com).

Here's the Panasonic DMC-G1:
http://www.imaging-resource.com/PRODS/DMCG1/DMCG1A6.HTM

Here's the Sony A350 (note the separate timing for Live View):
http://www.imaging-resource.com/PRODS/AA350/AA350A6.HTM

...
The Sony may well be the fastest, but the tests are far from the best. For one, they use radically different lenses. The Sony is tested with a noticably faster lens. Also, the Live View / No Flash result seems spurious. It shows a faster response time than using the optical finder. When the flash is used, the Live View time is some 40% longer than Optical. This raises a lot of questions about the accuracy of the tests.
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Old Sep 9, 2009, 9:40 PM   #26
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On the usefulness of the live view: Do you guys (w/o live view), when using a tripod and long shutter speeds, put the eyepiece cover every time on the viewfinder to block light entering it?
No. If I use the camera's meter, it is with my eye to the eyepiece. When the shutter is activated, the mirror flips up, blocking any light entering from the eyepiece. This is why the VF goes dark when the shutter is engaged. Why would this possibly be an issue?

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Old Sep 10, 2009, 7:15 AM   #27
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The Sony may well be the fastest, but the tests are far from the best. For one, they use radically different lenses.
They've been trying to standardize on using a Sigma 70mm macro lens for testing (since this lens is available in most camera mounts), to take lens differences between cameras out of the equation. But, for models that don't have this lens available, it's harder to compare them.

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Also, the Live View / No Flash result seems spurious. It shows a faster response time than using the optical finder.
When you use Live View with the Sony dSLR models, the design allows it to use the same 9 point AF sensor assembly that's used in non-Live View mode. Basically, all it's doing is sending the same TTL image that would normally go to the optical viewfinder to a separate live view sensor in the viewfinder housing when you're in live view mode.

So, you really shouldn't see any difference in AF speed either way (using the Optical Viewfinder or using Live View), as both modes use a fast, dedicated 9 point Autofocus Sensor Assembly to take advantage of faster Phase Detection Autofocus (versus a slower contrast detection method using the main imaging sensor that you find in many other camera models using Live View).

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When the flash is used, the Live View time is some 40% longer than Optical. This raises a lot of questions about the accuracy of the tests.
That is a bit curious. I assume it's being tested using Flash Assist for Autofocus, and it could have something to do with an artificial delay being imposed when sending information to the LCD to make sure the display isn't being impacted by the light from the flash (but, that's just speculation on my part). In any event, I'd suggest disabling flash assist with them anyway. I think flash assist AF is annoying to your subjects and the Sony dSLR models tend to AF well in low light without using flash assist.

Here's a image showing the design of Sony's Live View System from the A350 review here. Basically, when you switch to Live View mode, it's just tilting a mirror to send the same TTL image you normally see in the optical viewfinder to a separate live view sensor in the viewfinder housing. That let's it use the same 9 point AF sensor assembly you use in non-Live View mode, taking advantage of faster phase detection autofocus, like you'd normally have with an SLR/dSLR camera; versus requiring the use of slower contrast detection autofocus via a camera's main imaging sensor (as you'd have with point and shoot models or newer cameras like the GH-1 that don't have a dedicated AF sensor assembly to provide phase detection autofocus).

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Old Sep 10, 2009, 8:58 PM   #28
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Jim C:

Its easy to see why the Sony's LiveView approach should deliver the same focusing speed as seen when using the optical finder. It has its negative side though. You are not viewing with the same sensor as the one used for the final image. In most respects this should not be an issue. One issue, a big one for some, is that since you are viewing though the focusing screen aperture and using a separate sensor you will not be getting the 100% VF accuracy achieved by the more common approach. Also, any live histogram display would likely be less accurate, though likely accurate enough given the limited display precision possible.

Also, the need to use different lenses for the speed tests, while completely understandable, does make it impossible to make any precise comparision of the overall real world performance with a common mix of lenses. The substitution of a modestly slow mid-range zoom for their "standard" modestly long and significantly faster prime lens doesn't seem like the best choice, though choices are limited in m4/3 at the present. Hopefully that can standardize of a more appropriate test lens for m4/3 and update their posted results. As it stands, the tests don't support making anything other than very general approximate comparisons to the G-1.
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Old Sep 11, 2009, 8:26 AM   #29
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Actually, the Sigma 70mm is a relatively slow focusing lens (as most macro lenses are). I've seen it reported as having "sluggish" gearing. That's typical of a macro lens (since they're usually geared for very fine focus accuracy). See the AF section of this review for comments about it's speed:

http://www.slrgear.com/reviews/showp...uct/964/cat/30

But, that does give them a way to compare [most] dSLR models more fairly (taking lens differences out of the equation, since it's available for most camera mounts). I suspect the main reason they're trying to use that lens for most tests is sharpness, so that they have a very sharp lens for comparing image quality between dSLR models. My assumption is that they're using it for AF tests, too (but, they could be using the kit lens, as I don't see the lens used specifically mentioned in the performance section). In most lighting, the kit lens should focus faster than that Sigma.
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Old Sep 11, 2009, 6:06 PM   #30
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Actually, the Sigma 70mm is a relatively slow focusing lens (as most macro lenses are). I've seen it reported as having "sluggish" gearing. That's typical of a macro lens (since they're usually geared for very fine focus accuracy). See the AF section of this review for comments about it's speed:

http://www.slrgear.com/reviews/showp...uct/964/cat/30

But, that does give them a way to compare [most] dSLR models more fairly (taking lens differences out of the equation, since it's available for most camera mounts). I suspect the main reason they're trying to use that lens for most tests is sharpness, so that they have a very sharp lens for comparing image quality between dSLR models. My assumption is that they're using it for AF tests, too (but, they could be using the kit lens, as I don't see the lens used specifically mentioned in the performance section). In most lighting, the kit lens should focus faster than that Sigma.
I think for AF, they should do both kit lens & a common lens used with all mounts. This gives a better indication of the normal performance that you can expect if people buy the camera from scratch.

I compared AF speeds between DSLRs and G1/GH1 & the Olympus E-P1(with standard kit zooms attached).
I first focused on my hand, then on something around 10m away, then back on my hand. (and then took the second and third focusing as the standard for each camera)
Here is the order of fastest to slowest:

Panasonic G1 (almost instant)
Canon 50D (very close to the G1)
Olympus E30 (quite a bit slower than the 50D)
Pentax K7 (slightly slower than the E30)
Sony A380 (slightly slower than the K7)
Nikon D300 (quite a bit slower than the A380)
Olympus E-P1 (a big margin slower than the D300)

The K7 was a bit of a surprise, since Pentax uses the in body screw to AF. Also a surprise was the Nikon being quite slow. No surprise with the E-P1. Not a scientifically conducted test, but a good indication as to how the micro 4/3 cameras perform in the real world.

Another interesting point, when I use the kit lens from the Olympus E-510 (14-42mm) on the G1(which is also own) via the Panasonic adapter, the Olympus lens' AF speed is quite slow. It seems to use the same out-in-out travel that characterizes the slowness of the Olympus E-P1 with its standard kit lenses.

Another lens to try across all mounts is the Sigma 70-300mm APO lens as Olympus 70-300mm (micro 4/3) is internally the same as the Sigma, so the Olympus could be used on the E-P1 & G1/GH1/GF1.

Last edited by dnas; Sep 11, 2009 at 6:08 PM.
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