Backfocussing Nikon E 50mm?

[Spider67]

Hi folks,

I again noticed in a wide open portrait that I had put the focus on the eye (nearer to the camera) but that on the photo it was on the hairline. I used 1/40 and f1.8 and checked again. It seems not to be blurred by camera shake.
Is it possible to have backfocus with an SLR lens although having put and checked the focus before?
Best of regards
Des

[David William White]

Camera on tripod?

Probably not a lens issue. Can you repeat with a longer lens (where the effect would be more pronounced)?

The distance through the lens, off the mirror, to the ground glass is supposed to be the same as the distance through the lens to the film plane. How's your mirror look? Is ground glass installed right way around?

[Spider67]

No the Camera was not on a tripod. As I said neither the camera nor the subject were moving. And it also happened using 1/60th. I am going to make a 50mm comparison on a D40. Its interesting as the hairline is really sharp whereas th eye is not. In my opinion that eliminates camerashake......but regardless of that yeah using a tripod and smaller apertures would aslo be a solution

[antiquark]

As I said neither the camera nor the subject were moving.

Were you, or the subject, breathing? :)

[Spider67]

Were you, or the subject, breathing? :)
you have to pay taxes for we try to keep that on a low level....
As I was taught photography by a WWII Veteran (....you shutt press ze relies batton ven breezing in not ven breezing out, Shweinhundt verdamt noch mal - Movie German used by courtesy of Mad magazine) I could try hyperbventilating the next time....

[Spider67]

Back focus can occur, remember you are focussing with the lens wide open. However it is more likely your camera is not showing correct focus.

that don't work. It is a mistake that puzzled me before and I thought maybe I should not focus with the center of the focusing screen and then change the framing.
But this time I did not move the camera as the D40 has no split screen uin the center.

[ZeissFan]

You're using digital? That's a different factor, as the screens in most of those cameras generally aren't optimal for manual focus.

When I shoot wide open with a Pentax K10D and a 50mm lens, I get spot-on focus about half of the time.

I would say that it's probably an inability to focus accurately due to the focusing screen and not the lens.

[dnk512]

Oh, you are trying to focus with a cropped sensor (tiny finder). Search the web about manually focusing cropped DSLRs. Very difficult. I had to replace my screen with a split prism one and after painful alignment I am now good.

[Brian Sweeney]

What Fred is pointing out is Focus Shift as a lens stops down for the exposure. You focus on an SLR with the lens wide-open. As it stops down, a shift will occur.

BUT: if there is a real discrepency in the focus, the mirror or Focus screen may be out of alignment. The path from the lens to the focus screen has to exactly match the distance to the CCD. If the distance is different, you will not be able to focus using the viewfinder. I've had that problem before.

[Spider67]

Seems I found the solution in Ansel Adam's book "The Camera",
So it was camera shake or rather "camera movement" as written in the German translation:

if you have a vertical movement horizontally oriented lines will be sharper than vertical lines and vice versa. In my case the hair being vertical was clearly sharper than the eye.
So thanks folks for the answers you showed me the right direction....I have to live with the fact that my hands shake more often than I think