Manual Focus--Wide Open--Does your Camera do This?

Started Dec 13, 2010 | Discussions thread
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robertbarber
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Manual Focus--Wide Open--Does your Camera do This?
Dec 13, 2010

Hi,

On the left is what my viewfinder looks like on the E-510 with my Minolta MC 55mm 1.7 wide open at 1.7. On the right is what the resulting image looks like. The camera was mounted on a tripod, and the photo taken with a timer.

Obviously the focus was missed. I tried to focus on the letter A and maybe ended up focusing on the on the letter B instead, due to the E-510's small viewfinder. However, there is no way that I focused on the letter D, which is in focus in the shot.

I have long known that my camera did not focus manual lenses correctly wide open through the viewfinder (It does fine in live view, of course), and thought that I found the explanation here. http://www.jayandwanda.com/photography/dslr_man_focus/man_focus.html . According to the article, microlenses in the focusing screen pass light to our eyes differentially according to the aperture of the camera lens.

I did not do a series of photos for this post at different apertures, basically because I'm too lazy to do it, but what happens is that the camera focuses a little bit better as the apertures become narrower; either that, or the greater depth of field hides the front focus. At any rate, it is not a problem to manual focus this lens at f8, even on the E-510. But I like to use it for the narrow depth of field, which is where the problem is. I have often tried to focus on my wife's eye, for example, in a portrait, and her eye turns out blurry, like the A's in the illustration. I used to own a Minolta MD 1.4 which was even worse wide open.

The E-3 should be better than the E-510 at manual focus at large apertures through the viewfinder, but in theory it should still show missed focus at apertures wider that f1.8. I have thrown this idea out to a couple of E-x owners. One says that he had the same problem. One said that he didn't. What does your camera do?

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