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Old Sep 6, 2004, 7:27 PM   #1
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I have a Nikon D70 and was getting to learn it and ran into something that maybe others have an answer for. In some cases the autofocus doesn't work well and the system has a hard time trying to focus and give me the green steady light with the beep. A guide book says to use manual focus and that if I have a F5.6 or faster lens that I can use the internal focus indicator in the viewfinder to confirm I'm in focus. The way this is done is by placing the focus indicator over the area I want focused and turning the focus ring on my 18-70 lense until the green focus indicator light stays lit up. The problem I'm having is that when I place the focus indicator over the focus point it has the same problem as when I tried to autofocus, the green light won't go steady it ends up flashing and I can't find any place where it stays steadily lit. Am I doing something wrong or is there a better way to tell if something is in focus? I have bad eye sight so I need some sort of visual indicator in the viewfinder.


I should add that my AF works fine for many things and I don't have to go to manual all of the time.
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Old Sep 9, 2004, 3:29 AM   #2
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any auto focus system has its limits. My understanding of the D70 is that its system (as with all SLRs) works by looking for contrast in the subject. Therefore, if you are trying to focus on atextureless object of a uniform colour, it would not be able to get a lock. This inability to get an auto focus lock also prevents the camera being able to confirm that your manual focus is spot on - the user booklet is probably not very clear about this.

try looking for an area of the subject that has some texture or contrast and focus on that specific point. with close up work where the depth of field is narrow, you would need to be careful that this point is actually the same distance as the point that you are really intending to be in focus.
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Old Sep 9, 2004, 4:25 AM   #3
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I agree with Timeless - the only times the D70's AF has a hard time is when there's lack of contrast (low light poses not much of a challenge but it may hunt around for a bit). If you attach a SB600 or 800 flash and use the AF illuminator function, it will help tremendously by overlaying red lines from the flash's LED increasing contrast to the camera's AF system.
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Old Sep 9, 2004, 7:32 AM   #4
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If you don't have an extrenal flash to help with the autofocus, I have also read where people use the little $10 laser pointers. Just hold it and point at your subject long enough for the camera to lock focus. I've also heard of people taping it to their camera ... looks like it'd be pretty easy to temporarily tape one to the flash socket.
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Old Sep 9, 2004, 7:42 AM   #5
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Hi,



Onyx, in another tread, you gave a link that explain in detail how the focusing system works. It really helped me to improve some aspect of my photography.

Can you repost that link since i can not find it anymore?

Everybody should read this document to make better use of the D70.

Thanks,

Luc
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Old Sep 9, 2004, 10:49 AM   #6
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Morris, I have no clue which link you're referring to, so sorry I can't repost it.

I'll see if I can locate what thread it was...
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Old Sep 9, 2004, 12:12 PM   #7
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So i finally found the link that explains how the focusing system of the D70 works. Pages 4 to 6 are very interesting.

http://md.co.za/d70/focus21.pdf
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