D.O.F? "Infront of focus point" vs "behind focus point"

[mandonbossi]

Hello, It has been a while since I have been on here and i am hoping that someone could please explain something to me.. I recently had a chance to play with a friends 8 x10 camera and his Nikon 300mm lens! Holy Moly! Truly an amazing thing to look through! My first time really looking through an 810.. Up until this point i have only ever used a 54.

The look I really seem to like of other photographers is a full body portrait, shot wide open on a fairly normal lens (300mm or so). I recently saw some of Alec Soths prints and they were really amazing! He is mainly who I am talking about with such portraits.. I have tried to achieve a somewhat similar look with 54 and the only lens I found that gave a close drop off in depth was the Xenotar 150mm 2.8 which I guess is similar to 300mm 5.6 on 810 format...

I have really struggled to achieve accurate focus when using this lens at wide open apertures.. I have given up on completely wide open and have settled for around f4 or so.. Still extremely shallow D.O.F. Still find it tricky when shooting people. Obviously when shooting 810, you have a much bigger negative to deal with but was just wondering how others dealt with this. I would presume if focus was off on a larger format, then it also becomes more noticeable as well?

So I'll get to the point raised in the heading.. I noticed in one of his shots (attached) that things seem to be more in focus in front of the focal point and they seem to rapidly drop off behind the focal point. This is all based on the assumption that he had focused on the girls eyes.. I have noticed a similar thing when taking my own photos with the Xenotar and the few I had done on 810. Do people ever focus "slightly" forward of what they are trying to get sharp? Or is that just dumb?

Hmmm, am not sure, would love to hear any opinions on this?

Best Regards

Mandon

[mandonbossi]

Sorry about that, here is the link. You should be able to zoom in on it.

Thanks again.

http://alecsoth.com/photography/wp-c..._5zL0069_F.jpg

[Paul Fitzgerald]

"Do people ever focus "slightly" forward of what they are trying to get sharp? Or is that just dumb?"

I don't think so. Wide open on 8x10 has so little DOF and DOF that any difference between the GG and film holder will shift the focus enough to throw off the picture. Differences between holders or film bowing can do this also.

[Brian Ellis]

. . . Do people ever focus "slightly" forward of what they are trying to get sharp? Or is that just dumb? . . . would love to hear any opinions on this?

That's a fairly common practice when trying to maximize depth of field. I did it with a 35mm or medium format film cameras (I use a different system of focusing a LF camera). Today with a digital camera I'm more likely to make multiple exposures while focusing at different points from near to far in the scene and then blending and merging the exposures in Photoshop.

[johnielvis]

could be using tilt too.....that's why you tilt..get the foreground in focus

[jp]

In that photo, if Soth aimed the camera down to get the composition, rather than keeping the camera straight and raising the back, the plane of focus would not be perfectly vertical and would be as pictured.

Older lenses like tessar rather than planar, or even triplets (which won't be so sharp) have a smoother in-out of focus range; doesn't drop out quite as fast, but still has a pleasing out of focus area.

Focus is 1/3 in front, and 2/3 in back, so focusing frontwards a bit will improve things in some circumstances. I'd say don't try to shoot it wide open, and find a lens that does what you want with the background.

[mandonbossi]

Hi, Thanks to everyone for all the responses, much appreciated! I feel like I may have confused myself with my last post and now upon readings others thoughts..

If i recall correctly, depth of field is greater in the latter 2/3 of an image (in a typical landscape image), hence the simplified rule of focusing roughly 1/3 into an image..

Does that mean that the latter 2/3 of an image are "sharper" than the first 1/3 or is it the other way around?
I thought it was the first option, is that correct?

In this image, at least in the area where focus initially starts to fall off, it seems the forward part of the image retains a sharper area than the area behind the subject..

If this is the case, I feel like maybe I should be focusing slightly behind the subject (if the area in front of the focus point is holding its sharpness better)

What do you think? Am I way off here?

Thanks again for all your comments and suggestions.

Best Regards

Mandon

[ic-racer]

Do people ever focus "slightly" forward of what they are trying to get sharp? Or is that just dumb?

If the thing you are focusing on is not the sharpest in the negative you have a film plane vs ground glass plane issue. The only reason to purposely focus on a point away from the point of interest is to make it blurry.

[cowanw]

If the thing you are focusing on is not the sharpest in the negative you have a film plane vs ground glass plane issue. The only reason to purposely focus on a point away from the point of interest is to make it blurry.

Unless you are using soft focus lenses, in which case you want to use the space either in front of or behind focu, depending on the lens.

[mandonbossi]

In response to IC-Racer, I have had my camera properly aligned to ensure that this is not the case and have shot stationary subjects with the 150mm Xenotar @ 2.8 and they have been sharp, so I have faith that this is not the issue... I guess the problem is, that I am dealing with people, who of course move.. So that is why I am trying to understand this problem in a way that incorporates this.. I realise that it is really dealing on the extremity side of things but think it must be achievable..

Maybe it is just a matter of more testing, some shot focused on the eyes, others a little behind..

Thanks again for the responses..

Anyone else have any other thoughts or suggestions?

Best

Mandon