Dustin Abbot's posts got me interested in trying some of my old manual focus lenses from various manufacturers. I had already fitted the 's' screen to one camera body anyway, though since adopting BBF I haven't really manually focuses AF lenses for many years now.
I think that is was Dustin who made the comment that when using manual lenses he got the occasional OOF image despite being sure that he had sharp focus in the viewfinder. I have found the same thing. I know that our eyes tend to adapt to slight OOF, a problem for people who wear glasses and a slightly inaccurate prescription can lead to headaches etc.
However I recently tried a chipped adapter, and found, 50% of the time, much more focus accuracy with the cameras AF confirmation than I can achieve by seeing the sharpest point of focus travel thorough the viewfinder.
When you look at how microscopical the setting of the camera's AF module has to be it makes me question the accuracy of a screen that we just drop into a tray and click up into place under the cameras pentaprism. It's hardly precise in locating the screen.
So my question is; how accurate are these so called manual focus screens anyway when using fast lenses ? Anyone have any hard fact information on this ?
I think that is was Dustin who made the comment that when using manual lenses he got the occasional OOF image despite being sure that he had sharp focus in the viewfinder. I have found the same thing. I know that our eyes tend to adapt to slight OOF, a problem for people who wear glasses and a slightly inaccurate prescription can lead to headaches etc.
However I recently tried a chipped adapter, and found, 50% of the time, much more focus accuracy with the cameras AF confirmation than I can achieve by seeing the sharpest point of focus travel thorough the viewfinder.
When you look at how microscopical the setting of the camera's AF module has to be it makes me question the accuracy of a screen that we just drop into a tray and click up into place under the cameras pentaprism. It's hardly precise in locating the screen.
So my question is; how accurate are these so called manual focus screens anyway when using fast lenses ? Anyone have any hard fact information on this ?