My backfocus solution...sort of.

[charlesphoto99]

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NOTE: THIS IS FYI ONLY! Attempt at your own risk.

 

At the risk of screwing up a perfectly focusing body (a replacement for my first lemon) I decided to tackle, or at least try and mitigate, the backfocus when stopping down on my 35 asph lux and 50mm pre-asph lux (already adjusted for perfect wide open focus by DAG).

 

My solution was to adjust the infinity roller first at 1 meter or thereabouts so the lens front focused as far as permissible when wide open and stayed within reasonable sharpness. I then adjusted the near/far cam (at the end of the arm where it connects to the body underneath a slotted screw) as infinity and mid distances were now off (very important to adjust this one too and not just the infinity hex!).

 

Looking into the mouth of the camera from below, it's counter clockwise for the infinty hex; clockwise for the near/far cam (loosen screw and then move the little pronged washer underneath. Tighten screw again. Note: This is not the adjustment peg in the far throat of the camera!!!! Don't touch that one.) Make small movements at a time! Adjust the near/far until the infinity focus patch is again aligned. May need to do some slight back and forth between the two. Be sure to check focus with 100% preview at near, mid and far distances.

 

So, this adjustment compromises the focus slightly when wide open (esp on my 90mm APO) but it improves greatly now with stopping down as it stays at the front edge of the focus range. The 35 lux never gets as sharp at 2.8-5.6 as I would like it to be, but at least now stays within reason (I could adjust farther but would throw other lenses off too much). I figure compromising wide open focus slightly is best, as wide open is usually indicative of a low light shooting situation where focus is going to be compromised one way or another - and one is going to generally get a more impressionistic look anyway.

 

My 28 Summicron is off at Leica for adjustment and coding - no idea how that'll do. My 24 focuses fine as to be expected (a seemingly bulletproof lens, one of Leica's best IMHO).

 

I think with the M8 we are fortunate to actually have the means at our disposal to adjust the focus (on the body) if so inclined. Same can't be said for dslrs. I think finding the correct focus with the M8 and a battery of lenses will always be a matter of fine tuning and making some compromises. Best to find that right balance that works for you and the type of shooting you do.

[Ian Kerr]

Very minor point...I believe the Canon 1D Mark III includes a function to fine tune the focus.

 

Cheers

Ian

[charlesphoto99]

Very minor point...I believe the Canon 1D Mark III includes a function to fine tune the focus.

 

Cheers

Ian

 

Hmmm, not so minor a point if you don't own a MkIII but own an M8 instead. The MkIII looks like a fine camera (I've held one briefly) but it is the first dslr to include a focus fine tune function.