Practical possibility of focus and recomposition on medium format

[Rollei6008i]

Since MF DSLR like Hy6(Hy6mod2) , P645 & P1 XF only have 1 point AF & in the middle of the sensor , besides XF have AFR function. Others have no such function .

I am using Hy6mod2 , when I need perform focus and recomposition , not every time success especially for portrait ; Anyone can give advice on some know how for that purpose ?

 

[robmac]

Not a whole lot you can do and wider apertures. You could tweak the focus just a hair rearward after focus, but it would be a crapshoot and lose moment. I use Hassy True Focus and it works like a charm.

 

[steve_cor]

If you tilt your camera up to focus, imagine that as a longer diagonal line from the film plane to the subject. Then when you point the camera straight ahead, the distance to the subject is along a shorter straight line. This means you have actually focused behind the subject.

If you are trying to focus on the eye, check if the picture is more focused toward the ear.

Doug Peterson has suggested to lean forward while focusing. Then stand up straight while shooting. If focus and re-compose cause you to back focus by three inches, then you would lean forward by three inches while focusing. Maybe you would like to experiment with that and let us know.


--Steve.

 

[robmac]

Not a whole lot you can do and wider apertures. You could tweak the focus just a hair rearward after focus, but it would be a crapshoot and lose moment. I use Hassy True Focus and it works like a charm.

Argh: I meant to type 'forward' above.

As the prior poster indicates, the focus point moves rearward as you swing the camera through the arc as you recompose.

Without focus points near the edges of the frame (to reduce the degree of rear-shift) or something like True Focus, you're better shooting with enough depth of field to give you a large enough margin of error.

Any non-technology solution is just a crap shoot where you try and improve the odds in your favour.

 

[Rollei6008i]

Up to now, it seems no solution . I only can sacrifice to use whole format(crop the top of the format) and focus on my point of interest ; e.g. eye

https://www.flickr.com/photos/54877744@N03/42016554574/in/album-72157694713625632/

 

[MGrayson]

This guy uses a Leica S, which has only the center focus point, and always does focus/recompose. http://markmannphoto.com.

I use center focus and crop, but then I seldom shoot portraits.

--Matt

 

[ErikKaffehr]

Hi,

Focus and recompose induces a systematic error. In addition the camera rotation may not be around the nodal point of the lens which also will shift focus.

There is no real solution the problem relying on AF for critical focus. The best solution is to use an EVF camera like the Fuji GFX or the Hasselblad X1D that use the sensor for focusing and have freely selectable AF points. But, those systems may still focus on the eyebrow and not the eye.

The second best option is to use magnified live view. You select where you want to focus, hit live view magnification and focus manually.

Peaking, if available, is pretty meaningless unless combined with magnified live view.

So, in theory, accurate AF is nearly impossible for off center subjects. In practice the focusing errors may be acceptable. Many great images have been made using cameras without a perfect focusing system.

Even magnified live view has some issues, as most lenses have some focus shift when stopping down. So, accurate focus needs to be done at shooting aperture.

Shooting at say f/8 would mostly mask small focusing errors.

Best regards
Erik

 

[jerome_m]

I am using Hy6mod2 , when I need perform focus and recomposition , not every time success especially for portrait ; Anyone can give advice on some know how for that purpose ?

Are you sure that you use the truefocus option and not simply focus hold?

 

[Rollei6008i]

Are you sure that you use the truefocus option and not simply focus hold?

"truefocus option" ? Would you like to talk more about this ? How does it work ?

 

[ErikKaffehr]

Hi,

TrueFocus is a technology developed by Hasselblad. It uses gyroscopes to detect camera rotation around two axes and compensate for the focus shift due to camera rotation.

It is described here: http://static.hasselblad.com/2015/02/using-true-focus.pdf

If the Rollei HY6 mod 2 has TrueFocus they would have it licenses from Hasselblad. I have never heard of that feature.

My take is that making full use of all the resolution of modern cameras is a very demanding task. But, all that resolution may not actually be needed.

Just as an example, normal DoF tables are based on a very lax definition of sharpness. This image would be considered sharp according to DoF tables:

The image above was defocused 9 cm at 3m shooting distance using at 100 mm lens at f/4.

The same lens gives this image when correctly focused:

If a print was made and viewed at a "normal viewing distance" that difference would not be very noticable by a normal observer. It is possible that the normal observer wants to look at some detail at moves in to scrutinize and in that case the lack of sharpness in the first image would be obvious.

Best regards
Erik

"truefocus option" ? Would you like to talk more about this ? How does it work ?

 

[Rollei6008i]

Dear Erik,


Thank you very much for your explaination , I think Hasselblad's TrueFocus is similar to XF's AFR function . Both are great performance .

Hi,

TrueFocus is a technology developed by Hasselblad. It uses gyroscopes to detect camera rotation around two axes and compensate for the focus shift due to camera rotation.

It is described here: http://static.hasselblad.com/2015/02/using-true-focus.pdf

If the Rollei HY6 mod 2 has TrueFocus they would have it licenses from Hasselblad. I have never heard of that feature.

My take is that making full use of all the resolution of modern cameras is a very demanding task. But, all that resolution may not actually be needed.

Just as an example, normal DoF tables are based on a very lax definition of sharpness. This image would be considered sharp according to DoF tables:

The image above was defocused 9 cm at 3m shooting distance using at 100 mm lens at f/4.

The same lens gives this image when correctly focused:

If a print was made and viewed at a "normal viewing distance" that difference would not be very noticable by a normal observer. It is possible that the normal observer wants to look at some detail at moves in to scrutinize and in that case the lack of sharpness in the first image would be obvious.

Best regards
Erik

 

[thebroketographer]

Not a whole lot you can do and wider apertures. You could tweak the focus just a hair rearward after focus, but it would be a crapshoot and lose moment. I use Hassy True Focus and it works like a charm.

+1 for TrueFocus; it works great, but does take some getting used to, to make the most of it.

 

[jerome_m]

"truefocus option" ? Would you like to talk more about this ? How does it work ?

Sorry for the delay in responding.

Your camera is able to correct the focus error due to focus and recompose and that correction is generally quite good. You'll need to activate that function using the camera's menu system. Check the manual, it has a pretty good explanation with figures.

 

[Rollei6008i]

Sorry for the delay in responding.

Your camera is able to correct the focus error due to focus and recompose and that correction is generally quite good. You'll need to activate that function using the camera's menu system. Check the manual, it has a pretty good explanation with figures.

Really !! I check the manual now .