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Old Jan 2, 2004, 2:19 PM   #1
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Default G400/500 Owners Opinion - AF in low light

I have been searching for a good P&S digicam with low shutter delay, and is also small enough for a pocket (1"-1.4" thick).

My travels have pointed me to the Minolta G400/500.

It looks like an all-around good deal, except for some nasty things I have been reading about low-light autofocusing.

If you own one, how does this camera perform? I imagine about 50% of my photos will be indoors at low light.
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Old Jan 3, 2004, 3:15 PM   #2
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I purchased the Konica Revio KD-510z in mid-July (I had one in my hands, about 2 weeks after it was released in Japan).

This is the same camera as the Minolta DiMAGE G500 (after the Konica-Minolta merger, they released the camera under the Minolta label in the U.S.).

I've taken thousands of photos with this camera using Autofocus, with the overwhelming majority looking just fine -- both from a focus and exposure perspective.

Most of mine were taken indoors in low light (my home, dimly lit restaurants, etc.).

I've been VERY pleasantly surprised at how well mine has worked indoors.

However, when we traveled to South Carolina over Christmas, I did have a problem with the camera focusing.

Interestingly, the light was better. It was at my stepdaughters house in Charleston, SC, where I was trying to take photos of grandchildren opening Christmas presents.

What was happening:

The camera was being fooled by the white lights on her Christmas Tree. It was giving a focus lock (with the tree being obviously out of focus). It's almost as if the focus system was working backwards (making the lights appear larger, as they do when out of focus).

So, there must be a firmware bug with the algorithms in some lighting conditions (as I experienced over the holidays).

My solution at my stepdaughters home: I simply switched to a 2 meter fixed focus and shot at wide angle. With this camera, 39mm equivalent is actually 8mm. So, at F2.8 (what the camera is going to select indoors), with a focus point of 2 meters, everything from 1.31 meters to 4.21 meters is going to be in focus.

This translates to everything in focus from 4.3 feet to 13.9 feet being in focus (where you'd be taking your indoor flash photos at anyway, if you wanted them to be within the flash range).

I haven't had time to try and figure out exactly what was happening. But, it was obviously being fooled by the lights in the background.

When I selected a focus point on one side of the tree, it was fine. But, when I selected a focus point with the bright lights from the tree in the focus area, it misfocused (yet gave a focus lock indication).

So, I'm speculating that this may be why some users are having great results in low light, and others are not (certain lighting conditions with lights in the background can fool the focus algorithms).

Even the reviewers disagree:

Steves-Digicams review indicated the camera had suprisingly good low light focus. Yet, dcresource.com indicated that the focus "wasn't great" in low light.

I originally thought that it could be a batch of defective cameras (since I know of one user that had a severe problem with his first camera, that a replacement camera fixed).

I'm not yet ruling this out, but there does appear to be a "quirk" with the focus algorithms in some lighting (white lights from a Christmas Tree in the background of focus area, in the conditions I had a problem).

In any event, the solution is simple. Switch to 2 Meter fixed focus, and your shots from 4.3 feet to 13.9 feet at wide angle will be in focus.

See this handy DOF calculator:

http://dfleming.ameranet.com/dofjs.html

Plug in Konica KD-500z (same lens and sensor), 8mm (wide angle), 2 Meter focus point, F2.8 and calculate. This is what you'll have indoors using fixed focus.

But, this is the only time I've had to resort to using manual focus indoors (at my stepdaughters house with the Christmas Tree in the background). In other indoor conditions, my camera has focused fine.

As far as the "quirk" I found with the focus algorithms (bright white christmas tree lights in focus area) in my KD-510z/G500, I suspect that they'll be a firmware upgrade at some point to correct it. Konica-Japan has released firmware upgrades for all of the previous models in this series (KD-310z, KD-400z, KD-410z, KD-500z).

These upgrades improved startup times, autofocus times, cycle times, white balance and more. So, I'd also expect one for the new KD-510z/G500 at some point, to improve on any bugs introduced from the firmware rewrite.

Since both Konica and Minolta have a good history of providing upgrades to improve their cameras, I see no reason why this would not continue after the merger.

The Konica KD-510z (Minolta G500) did represent a major overhaul of the firmware, compared to the Konica KD-500z. New features include User Adjustable ISO speeds, contrast, sharpness, color (red, green, blue channels), longer exposures, manual exposure, noise reduction on exposures 1/2 second or longer and more. So, a few "quirks" were bound to appear.

One of the reasons I bought the KD-510z, was because users seemed quite pleased with the older KD-500z (even though it provided very little in user control), and I knew that Konica-Japan had an excellent history of providing improvements (multiple firmware upgrades were released for previous models). So, I reasoned that if any major problems occured, they would likely be fixed at some point.

So far, the quirks I've found have been pretty minor, and I've been quite pleased with the camera.

This is my 7th Digital Camera. Having a camera that I can take with me everywhere in a pocket is wonderful. In the past, I'd often leave my larger cameras at home (except for special occassions, etc.), and often missed many photo opportunities.

Now, I can pull my Konica out of my pants pocket, and take a photo "on a moments notice" -- especially thanks to it's 1.3 second startup time.

Even if they never upgraded it, I personally wouldn't trade it for any other pocketable model. I really like mine.

See some photos from my camera at the link below (along with links to my user review).

http://www.pbase.com/jcockfield/konica_kd510z

Now, as for the G400 -- that's a different story. The G400 is using a totally redesigned focus system. It's a different "animal" entirely -- new body style, new sensor size, new lens, new focus system, new menu system, etc. It has little resemblance to past Konica models (KD-310z, KD-400z, KD-410z, KD-500z). The G400 is the same camera as the KD-420z.

Virtually every user I've seen with the camera has mentioned low light focus problems. Even Steve's review conclusion mentions it (the opposite of the findings with the G500).

So, with either camera, I'd air on the safe side, and buy one from a vendor with a no restocking fee policy. Then, if you're not pleased with the camera, you can return it for a refund or exchange (I know of one user that had a bad G500 from a focus perspective, but his replacement his working great.
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Old Jan 3, 2004, 9:10 PM   #3
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I have the g400. In typical indoor lighting - ex - plenty of light to read - it fails to lock focus the majority of the time. Other small cameras I've used in the same settings (S4, S400, P10) have no problem at all locking focus. Queries to Minolta about this issue go unawered.

You can continue to shoot without focus lock and the picture often comes out ok, but that's just by luck. If your subject is outside of the 'default' range, it'll be blurry. Even if it's in the default range, it's still not as sharply focused as it should be. You can use manual focus, but that defeats the whole purpose of a point and shoot camera.

The camera does achive focus lock much more often when using some of the 'scene' modes. I have no idea if the focus algorithm for the scene modes is better than the 'Program' autofocus, or of the scene modes just set a pre-determined focus range and use that.

I would not recommend the G400 if you're planning to do a lot of shooting indoors. It's a fine outdoor camera, but Minolta completely dropped the ball on indoor focus. Their failure to respond to repeated emails about the problem pretty much ensures that this will be the last Minolta I own, too. It's a shame, too. If the camera was at least average compared to other ultra-compacts inside, they'd have a real winner. As it stands, they've got a nice, fast, small, inexpensive camera that works well outdoors and is a complete gamble on indoor shooting, and they fail to respond to concerns from customers over it.

Maybe repeated bad reviews like the one recently posted at this site will encourage Minolta to address this problem.
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Old Jan 4, 2004, 3:57 PM   #4
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Here you can see a brief description of the scene modes .
http://www2.konicaminolta.jp/english...e-g400/05.html


@JimC , according to the DOF calculator you have refered to , with the focus set to 2,5 using the G400 at wide angle ( 5,6mm , 35mm equivalent =34 mm ) and an Aperture of 2,8 would give you a focus range of 0.32m to infinity , set to 1,2m would give you 0.28m to infinity , and 0,8m would give you 0.25m to infinity .
Even if using the smaller Aperture ( 4,9 ) would give you almost the same in-focus range .
I’ll have to play around with that tomorrow , seems really intresting !
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Old Jan 4, 2004, 4:02 PM   #5
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Yes -- It's a handy calculator...

The G400 does have a greater Depth of Field than the G500 (because it has a wider wide angle). So, using a fixed focus choice may be a good way to get sharp photos with it indoors -- bypassing any Autofocus issues.

I haven't used the G400, so I can't really comment on it's performance (other than what I've heard from others).
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Old Jan 8, 2004, 10:20 AM   #6
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Default G400 focus

I own a G400. Mine focuses perfectly indoors in near total blackness. It focuses in all light conditions to almost black to all shades of darkness to sunlight. It focuses in all scene modes and settings and distances. One other user in another forum mentioned that his does too, but most users are having a problem in this area. I don't know why two of us are not having a problem, but I'm not complaining!
Perhaps the reason is that when you try to focus by pressing the shutter half way a little green light stays lit when it is focused. On mine the little green light always flashes in low light, which is supposed to mean it is not focused. However, I just take the picuture anyway and no matter the distance or setting, it is always perfectly focused. I can only believe that users are commenting on the flashing green light saying it cannot focus and not commenting on the end result which is always in focus. I have taken about 100 indoor pictures with low light and without a single exception, they are all perfectly focused.
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Old Jan 8, 2004, 11:54 AM   #7
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Default Re: G400 focus

Quote:
Originally Posted by luvmywife
I can only believe that users are commenting on the flashing green light saying it cannot focus and not commenting on the end result which is always in focus.
Exactly. If the green light is flashing, the camera does not have focus lock. You can take a picture and it might come out in focus - if your subject is within the range the camera defaults focus to when it can't lock. Small digicams have a huge depth of field, so this range is pretty large. However, the inability of the camera to accurately lock focus is still a problem. If your subject is outside of the 'optimal' range, it will be out of focus. Even if it is in the optimal range, odds are it still will not be as sharply focused as it would have been had the camera done its job.

The fact that some images come out ok doesn't negate the fact that the G400 can lock achieve focus -lock- in conditions where every other small camera I've tried has (S4, S400, P10, P8). The low-light focus ability of the g400 is well below average in its class and is a detriment to the quality of the photos it takes in those situations. Minolta needs to address the problem or stop marketing the camera as an AF camera. It works great outside and in good light, but it is ineffectual in moderate indoor lighting.
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Old Jan 8, 2004, 10:55 PM   #8
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Default G500 and low light focusing

Quote:
Originally Posted by JimC
(snip)

I've taken thousands of photos with this camera using Autofocus, with the overwhelming majority looking just fine -- both from a focus and exposure perspective.

Most of mine were taken indoors in low light (my home, dimly lit restaurants, etc.).

I've been VERY pleasantly surprised at how well mine has worked indoors.

....

The camera was being fooled by the white lights on her Christmas Tree. It was giving a focus lock (with the tree being obviously out of focus). It's almost as if the focus system was working backwards (making the lights appear larger, as they do when out of focus).

So, there must be a firmware bug with the algorithms in some lighting conditions (as I experienced over the holidays).

(remainder snipped)
Jim, thanks for all the helpful information you've provided about the G500/KD510z. I just got mine a few days ago, and I haven't had time to explore all its capabilities. I'm impressed with many of its attributes, but so far I find its low-light focusing ability less than impressive.

In one test, my G500 failed to achieve focus lock on a patch of carpet, where both the Panasonic DMC-LC20 and Olympus C4000 were consistently able to lock. The Panasonic DMC-LC5 was consistently unable to lock on the same patch, and the Olympus C2100 failed to lock in about half of the attempts made with its focus assist illumination turned off. (FWIW, the light level was such that the C4000 metered the shot at 1/3 to 1/5 second, f/2.8 at ISO 400.)

However, the situation got very interesting when I tried varying the exposure. When set to underexpose by 1/3 stop, the G500 acheived lock at about the same rate as the C2100. Underexposing by 2/3 stop, it locked most times. And at (nearly) full stop underexposure, it consistently locked.

Note that in this test, I'm only testing the focus lock indicator. I don't know if any of these cameras were focused accurately when they claimed to be locked! I was just surprised that the exposure compensation setting had so much effect on focus lock.

Could this be related to your experience with white lights fooling the focus lock?

Robb
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Old Jan 9, 2004, 9:07 AM   #9
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Which firmware are you running? 3.00a by anychance? Trying to find out if it is firmware related as some of my low light pics look very grainey etc (hope we can update firmware!) see other thread about firmware for this camera (g500/kd510)
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Old Jan 9, 2004, 3:35 PM   #10
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Robb:

Startling Revelation! Yes, the variation between units we're seeing assumes to be related to the signal strength from the CCD. More on this later, but I have verified your results, and the focus does appear to be accurate using a negative EV compensation.

I had an interesting problem with a Sony DSC-P10 (unable to focus accurately indoors, regardless of what I tried). Yet, all outdoor shots were slightly overexposed.

This explains it! When the signal strength is too high from the CCD, then it is impacting the ability of the camera to distinquish contrast from the pixels!

Interestingly, using negative exposure compensation does not seem to negatively impact exposure (the flash is probably compensating for what the CCD is seeing).

Marvelous find! It explains much.

Mat:
Yes, I'm running 3.00a
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