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Focus Trap - fernando (1 Viewer)

The Dandelion chip also has the ability to be programmed to adjust the focus confirm point, so you don't have to tinker with the AF eccentric bolt (which would affect the AF point for all lenses). I find the "green dot" confirm gives better results (more repeatable) than my eyeball for manual focus lenses ...
 
I didnt realise that they had the name ' Dandelion '

I've got 2 of these adapters for a couple of my DSLR lenses, and yes, i prgrammed them to the lens they fitted, and you get EXIF data, and the ability to correct front or back focus.
 
If i'm understanding you correctly, there is a menu function in my some cameras to "offset" the auto focus instead of having to alter the mirror manually.

http://stanfordphoto.blogspot.com/2007/07/how-to-test-autofocus.html

Sorry if this isn't what you are talking about...


The mirror you see when you take the lens of your camera is the mirror that reflects the image to the viewfinder and that's the mirror that can be misaligned.
So, behind that mirror there's a eccentric bolt (two actually, but the other is for the AF sensors, forget the other, you only need the first for this), that bolt aligns the mirror so the image it reflects is aligned at the same plane of the sensor.
The easiest way to check it is to get the fastest lens you have, preferably one that focus very close, a macro lens is about perfect. Put your camera on a solid tripod, get a ruler, focus manually on any number, keep the lens wide open, put the line referring to the number at the exact centre of DOF on the viewfinder, if the mirror is misaligned the resulting image will have that dof decentered from the line you focused on. If that's the case you'll need to either send the camera to nikon, or mess with that bolt until it's right. I'm a DIY guy so you know my choice
 
That’s AF, that will not align what you see in the viewfinder. It is useful to adjust the AF too when using focus trap, as that is dependent of AF accuracy. But the viewfinder must be correctly aligned nonetheless, and the only way to that is with the bolt or shimming the focus screen.

Also not all cameras allows the AF adjust, luckily as said by the others, Dandelion chip allows that adjustment in the programming mode.
 
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I don't think there's any technique involved except having decent eyesight. With time the eye gets "educated" to see the needed details to distinguish what is or not focused, but still even in the beginning anyone with a good eyesight should have a better keepers rate than that.

The mirror you see when you take the lens of your camera is the mirror that reflects the image to the viewfinder and that's the mirror that can be misaligned.
So, behind that mirror there's a eccentric bolt (two actually, but the other is for the AF sensors, forget the other, you only need the first for this), that bolt aligns the mirror so the image it reflects is aligned at the same plane of the sensor.
The easiest way to check it is to get the fastest lens you have, preferably one that focus very close, a macro lens is about perfect. Put your camera on a solid tripod, get a ruler, focus manually on any number, keep the lens wide open, put the line referring to the number at the exact centre of DOF on the viewfinder, if the mirror is misaligned the resulting image will have that dof decentered from the line you focused on. If that's the case you'll need to either send the camera to nikon, or mess with that bolt until it's right. I'm a DIY guy so you know my choice ;)

Here's a link that explains all this better:
http://www.leongoodman.com/d70focus.html

The article refers more to the AF part, but the process is nearly the same.

Thanks Fernando,

The link you provided was very informative. I'll try it over the weekend, too bad I had only a 18-200mm f3.5/5.6 lens but I'll give it a try first.
 
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