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Old Sep 30, 2004, 4:09 PM   #1
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I'm thinking of getting the Fry's Outpost version of the C-755 (350+tax). It is basically a C-750 in a black case that has about the same amount of plastic as a C-740. Went to Fry's electronics at lunch and played with a C-740, the C-755 and a Stylus 410. None of these had flash cards in them.

The Stylus would autofocus on most general views around the store, albeit with the indication it would use flash. The 740 and 755 would not indicate autofocus lock at any scene in the store, which was fairly brightly lit (1/30 at f2.8 no flash). There were large square sharp edged light fixtures in the ceiling, which were almost too bright to look at directly. Placing the edge of one of these in the center of the frame, either horizontally or vertically, indicated an exposure of 1/800 at f4.0 in apeture priority ASM, but it still would not indicate autofocus lock (the green dot was still blinking)

I know the AF low light performance is considered poor, but is it THAT bad, or is it maybe that there was no flash card in the camera?

I would have thought a 1/800 f4.0 scene would have enough light to autofocus. My D-520 will autofocus on the brighter portions of the interior of my house, which is not as bright as it was inside Fry's. If C-7xx will not autofocus AT ALL in interior shots, but only in direct sunlight, that is indeed poor.
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Old Sep 30, 2004, 4:57 PM   #2
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Not that bad - might have been bad cameras. They are somewhat inconsistent - occasionally I have trouble getting AF lock in good light - and occasionally I get accurate AF lock in very low light. Better performance at wide than tele, obviously. Generally been very happy w/ the camera considering theprice - so I wouldn't let this experience deter you. Go elsewhere and look at other floor models to confirm.
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Old Sep 30, 2004, 9:06 PM   #3
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I think a lot is a lack of knowledge...for instance not knowing what is needed to get a focus lock, the fact you need a certain light level and a vertical contrast (if you have a horizontal contrast you rotate the camera to get a focus lock and then rotate back to take the picture):
http://www.howstuffworks.com/autofocus3.htm

Also, you don't want zoom in in lower light situations...the more you zoom in, the less light that enters the camera.

Personally I use my C-700 indoors all the time, but I understand the limits of photography, and for many of my indoor shots I do use a tripod. If I can't get a focus lock, I either focus manually, or (if safe to do so) use a laser with a line pattern so the camera can lock on.

Many here might add a comment about the lack of auto-focus assist (AF) beam, but an AF beam is only good for 15feet MAXIMUM!
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Old Oct 1, 2004, 4:01 AM   #4
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Thank you very much for your responses.

I am an experienced photographer, and spent one summer during college doing photography professionally. I am currently a degreed electrical engineer. I quite understand the mechanics of contrast detection autofocus.

In Fry's, both the 740 and 755 would not autofocus on an image where the left half of the frame was essentially black, and the right half of the frame was essentially white, with a very sharp transition between the two areas, producing a VERY distinct vertical edge, passing through the center of the frame. The right half was sufficiently bright to give a 1/800 f4.0 exposure reading for the overall image. My current D-520 will autofocus on central vertical edges that are much less bright and have much less contrast. I was very suprised that these cameras would not, and speculate that maybe these models won't indicate autofocus lock on ANYTHING if the XD flash card is not installed, even though the Stylus 410 would AF lock without its card. The cards are not present in all the display cameras so people won't walk off with them.

Anyway, I take your responses to mean that these cameras are capable of autofocusing with at least some interior illumination levels, and they do not require bright outdoor sunlight before the autofocus will work at all. Is this correct?

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Old Oct 7, 2004, 4:44 PM   #5
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It was the missing XD card that was causing the autofocus problem.

I received my C-755 from Fry's Outpost this morning and played with it a little at lunchtime.

With the XD card installed, it will autofocus just fine on a variety of indoor subjects with ambient noontime window lighting.

With the XD card removed, I cannot get it to indicate autofocus lock at all.
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