tom_luongo1 Posted May 7, 2008 Share Posted May 7, 2008 Why aren't the D300 AF cross sensors spread throughout the viewfinder instead ofthe 3 center columns? Every once in a while I find I'm in a situation where thehorizontal sensors don't quite cut it. Link to comment Share on other sites More sharing options...
hans_janssen Posted May 7, 2008 Share Posted May 7, 2008 Can you imaging the size of the piggy back mirror, at the back of the main mirror, that reflects the light to the AF unit in the bottom of your camera, when you spread the AF through whole frrame? Link to comment Share on other sites More sharing options...
Richard Williams Posted May 7, 2008 Share Posted May 7, 2008 Tom is talking specifically about the 15 central cross-type sensors: http://www.dzone2.com/productimages/p1000808/1000808NA24.jpg The AF area is already quite a bit wider than this, but the outer sensors only operate in a single axis and so can be less effective depending on the orientation of the subject. I don't know the answer to this question - placing them along a horizontal line might seem a bit more logical, but the D300 has some quite complex AF modes that use sensors in various combinations, and perhaps there were technical limitations on where the x-sensors could be placed. Link to comment Share on other sites More sharing options...
tom_luongo1 Posted May 7, 2008 Author Share Posted May 7, 2008 Though you never hear anyone complaining about it, on a D3 the clustering of the cross-sensors is even tighter. Does anyone know where I can find a diagram of the "piggy back" mirror assembly? Sounds like something behind the primary mirror which must be only partially reflective so that light passes through and reaches the AF unit. If they reduced the reflectivity, would that improve AF performance at the expense of having a dimmer viewfinder? If I could spread out 8 more cross-sensors, I'd probably add them something like the image below. Maybe they are working on this for the D400.<div></div> Link to comment Share on other sites More sharing options...
liljuddakalilknyttphotogra Posted May 8, 2008 Share Posted May 8, 2008 Personally I want sensors further out than they are now. It leaves too much area I have to maneuver the camera around to get a good sensor to use. I want the edges smaller..... Lil Link to comment Share on other sites More sharing options...
walterh Posted May 9, 2008 Share Posted May 9, 2008 The more you move off the optical axis the more difficult it gets to find exact focus. So it is not that Nikon is just not aware of the problem it is just technically more difficult and more inaccurate to have the AF points further away from the center. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now