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RF Spot Focus after Re-composition


Etruscello

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The M240 may solve this problem but, in the meantime with the M9 or M8, how does one maintain a spot focus after re-composing, i.e., re-framing an image? For example, if one wants a full body image of someone with focus on the eyes, the photographer places the eyes in the center of the compostion for the purpose of focus, then re-frames for the full body, placing the eyes closer to the top of the frame. The critical focus then shifts from the eyes to the belt buckle or handbag or whatever and the eyes go relatively soft. What do you do? How do you compensate? Do you move the focus ring a smidge? In what direction? Do you focus bracket? How many bracketed pictures -- in what direction do you turn the fucus ring, to what degree? What works for you? I'd appreciate your sharing your techniques, successes and failures. Thank you. Tom

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I'd say there are more important things to worry about. Shooting hand-held with people standing I'd expect body-sway to have more effect in most cases. I've used Leica for 50 years and it hasn't been an issue for me, but I don't use 0.95 lenses...

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Tom, there've been a number of threads on the topic, and I'm not sure I remember the outcome.

 

IIRC, to overcome the problem you're describing, it's recommended to lean slightly backward after recomposing.

 

If I'm wrong, someone will likely jump in with a correction pretty soon. :)

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I agree with what Tom says, but I think in some cases where focus is critical it may be easier and a touch quicker to move yourself forwards or backwards a touch rather than to try and fine-adjust the focus. I'm not sure there are any hard and fast rules -- it's about what works for you and gets the picture...

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JAAPV -- thanks for the link to FAQ, but I don't see a question there comparable to mine. I am not looking for general focusing information; rather, for focusing information relevant to re-composition. Tom

 

It's only a 'problem' if you're using a Noctilux or Summilux at close range. At f2 and less, the very slight shift in focus is otherwise within the depth of field IMHO.

 

However, there is another thread on the subject where someone has calculated the amount of shift to compensate for. http://www.l-camera-forum.com/leica-forum/leica-m9-forum/288697-focusing-m9-m240.html

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JAAPV -- thanks for the link to FAQ, but I don't see a question there comparable to mine. I am not looking for general focusing information; rather, for focusing information relevant to re-composition. Tom

 

Tom--

The final paragraph of the FAQ Jaap suggested applies directly to your question:

 

Note that when one focusses and recomposes the camera will turn. For geometrical reasons one must bend slightly backwards to keep the focussing distance constant.

 

For specific values, see Bert's calculations in the focus/recompose thread James just mentioned:

 

... the summary is that for 21, 35, 50 and 75 mm lenses you have to move your camera away from the object when focussing at closest range and full aperture by 157, 57, 27 and 11 mm respectively
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