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Old Oct 10, 2002, 4:14 PM   #1
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Default Autofocus woes

I have searched and read recent posts concerning autofocus problems and have not found any of the answers really helpful. I find that my 7i autofoucses readily up to about 100 feet, but is problematic at distances beyond that. Even though I get focus confirmation, about every other shot contains a subject that is slightly out of focus. I am aware of camera shake problems and the reciprocal relationship of required shutter speed to focal length. I do find that using spot focus helps. By comparison, my Olympus C2100 produces images that are far sharper even with the optical stabilization turned off and zoom at max. I hear that this has been quite a problem in the history of D7s. Has it really improved with the 7i?
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Old Oct 10, 2002, 7:12 PM   #2
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Welcome to the world of the Dimage 7's. Actually the 7i autofocus is supposed to twice as fast as the original 7, and more accurate too. Now aren't you glad you didn't get an original 7.

I have a 7 with upgraded firmware (V2). Even with the new firmware, I still find the autofocus to be unacceptable. As a result, I almost always shoot in manual focus mode. Since I almost always shoot at the wide end of the focal length, this usually works most of the time. Yes, I do occasionally get an out of focus shot. But in autofocus mode I often miss the shot completely because the damned thing cannot lock on.

I consider the autofocus to be the single biggest failing of this wonderful little camera.

Cheers,
Declan
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Old Nov 15, 2002, 11:21 PM   #3
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There has been quite a bit of discussion about this topic recently on dpreview. Some 7xx cameras indeed exhibt a problem in the wide area focus mode (the rectangle vs spot) where focus confirmation is aquired when the scene is out of focus. Jim Collins even determined that with his 7i, it is often possible to get focus confimation with the lens cap on. Others confirmed this with thier 7xxs On the other hand in spot mode, confirmation was never obtained with the cap on. Give it a try.
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Old Nov 16, 2002, 6:11 AM   #4
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The D7's like all camera of this type rely on contrast to determined the autofocus (unlike the more accurate phase detection splitter used on SLR and dSLR). They don't have a prism and the related optics remember to bring us the cameras @ theses attractive price levels.

In some circumstance especially when there are a lot of items to autofocus on like backgrounds or trees/leaves. The camera will focus on the wrong thing (ie its contrast was OK for the camera). It just not as smart as the photographer.

I think Minolta realized this that's why they have put it the "Direct Manual Focus' overide, but also pushing and holding in the select button will switch you to the flex-focus where you can point the AF point to anywhere on screen (ie where you want the contrast delta to be optimized).
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Old Nov 16, 2002, 12:17 PM   #5
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NHL

You are right, and I agree, but what is with getting focus lock confirmation when there is absolutly nothing on which to focus, as with the lens cap on? I have also reviewd the EXIF distance data froma a lot of my older pooly focused shots using the focus rectangle. In many cases their were no objects on which to focus in the indicated distance. I always kept trying until I got focus lock confirmation. It just appears that some units, far from all, have problems with the wide area focus rectangle.
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Old Nov 16, 2002, 6:36 PM   #6
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By the way. According to Steve's review the 7i uses phase detection auto foucus. See paragraph 4 on this page:

http://www.steves-digicams.com/2002_...age7i_pg5.html
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Old Nov 17, 2002, 12:16 PM   #7
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charlibob

There was a link to a FAQ on the Minolta site (now say HTTP error 104) that describe the AF on the D7's.

Not to contradict anyone, but I find it difficult to implement a phase detection on the flex-focus feature of the camera unless the phase detectors / splitters are servoed to the moveable AF cursor which will make it quite expensive to implement... The phase detectors are usually placed in fix positions in SLR.
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Old Nov 17, 2002, 1:09 PM   #8
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Looks like you are right NHL. Check out Marco Menardi's replay to my post on auto focus problems and Exif information on dpreviews. It appears that Minolta actually tried phase detection initially with the D7 and then went to video auto focus, as it states in the manual. Apparentlly Steve used old info when he wrote that paragraph in the review.
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Old Dec 2, 2002, 5:40 PM   #9
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Default Follow up after trip to Minolta

I had to send the 7i in for repair to the flash. Just got it back today. The flash works fine again and I was eager to try some definitive autofocus test to see if I needed to send it back to Minolta for a check up in that area.

First off, tried the focus lock with lens cap on test. Had not tried it previously. Was not able to obtain focus lock confirmation with the cap on, much to my relief. Next I tried shooting outdoors at various focal lengths and under various lighting conditions. First used the wide are focus rectangle, and later spot focus. To my surprise and joy, I had very little problem getting focus. even on troublesome images like distant foliage. One thing I noticed right off is that the smaller focus rectangle that lights up within the large rectangle, was almost always centered, rather than off in one corner or the other as before. Minolta definitely made some adjustment OR just perhaps the improvement comes as a result of them having performed the default reset. They say that they cleaned and adjusted the camera as well as fixing the flash, but who knows what that really means. All I know is it does autofocus very well now, and I could not be happier.

Only one problem. With the default reset, my files were reset to oooo. Solved that problem by searching my hard drive for the highest pict #, and then changing the last new # on the CF card to one higher using the pc's file manager and a card reader. Counting from that number now.

If you are having autofocus problems, it might be worth while doing the default reset to see if that helps. Otherwise I would encourage anyone to send the camera back to Minolta for warranty service.
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Old Dec 2, 2002, 9:05 PM   #10
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The default reset may be worth a try. My autofocus is hopeless, which is why I have gone to almost 100% manual focus.
I would have thought that the software upgrade from V1.x to V2.0 (on my original D7) would have performed the default reset, but who knows.
Unfortunately, sending my camera in for repair is just not feesable at the moment, and everything else works just fine.

Thanks,
Declan
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