Focus calibration?

[hammam]

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Lately, I've seen a «focus calibration» issue mentioned a few times, here and on another Leica forum. Whats is this exactly? Does it mean that the M8 needs a calibration of focus with each lens? Does it mean that some pictures I find out of focus, when I thought they were right on, have in fact fallen victim to this problem, not that my eyes are failing me or my hands are shaky in these instances (though they are, in many others )? Thanks.

[jaapv]

Olivier, I think you need to search this forum a bit more. The infinity focus on the M8 is easily user-adjustable and may need adjustment "out of the box", just like film M's. For the rest, a digital sensor is far less forgiving than film, so some focussing problems are coming out of the woodwork, added to that some non-rangefinder new M8 users are finding their focussing feet with the very recognisable bumps and setbacks we all went through, and we can do 100% crops that equal king-size bed sized prints, so it seems like a huge issue. Which it is not. Not belitteling those of us that do have lenses and/or cameras that are really off, they have a real problem that must be solved, but it is a minority.

[ho_co]

Olivier--

It is surprising to me as well how many people are discovering that they are unhappy with their equipment's ability to focus.

 

In close to 20 years of working with Leica in the 70's thru 90's of the last century, I never heard of an M camera coming out of the box with a misadjusted rangefinder, but that is clearly happening at least occasionally now. Some posters claim that Leica is known to be having problems with the consistency of rangefinder alignment in M8's leaving the factory.

 

Others have turned up citations that some lenses are better suited to a sensor than others, which are nonetheless fine with film.

 

In regard to the M8 finder, it is different from those of earlier models. One poster has even suggested that it is tested by eye on the LCD screen, not mechanically/optically as was the case with earlier cameras. I doubt that that's the case, but I don't know.

 

In regard to lens properties, in my opinion there are decent arguments on both sides of the matter. However, there was no such outcry when the DMR came out, and I doubt that Leica decided to use a different lens design philosophy for the rangefinder than for the SLR.

 

Jaap's description of our mechanisms for testing the sharpness of lenses are on the money. As users, we don't check the lenses the same way we used to.

 

We could use more info from Leica on how different the M8 rangefinder really is from the previous designs, and whether the same jig and chart are used for its calibration. As for the lenses, we could use clarification from Leica on what difference the flatness of the sensor makes and whether its influence is affecting new designs.

 

One argument for the side that says that some older lenses are less good when used with a plane sensor could be derived from the fact that Leica introduced a new, flatter-field 28mm for use as a basic lens on the M8. Of course, one could argue just as well that it was time for a new and less expensive 28/2.8.

 

You've raised a good question, and we need to follow it through.

 

--HC