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Thread: Contax 645 lens curvature issue with MFDB?

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    Contax 645 lens curvature issue with MFDB?

    The Contax 645 is considered a good choice for an affordable MFDB camera system, even though it was designed for film, so I would like to ask if the curvature of lenses designed for the Contax 645 and similar generation systems is likely to be a problem shooting digital that (according to this thread in the LF section) is a problem when using older LF lenses with MFDB?

    Or is this just theoretical hogwash that makes no noticeable difference to focus at the margins of a printed image?

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    Re: Contax 645 lens curvature issue with MFDB?

    I use LF view camera lenses on a P25+ and have zero problems. All my film Pentax 645 film era lenses on my Pentax 645D are fine, although there are a couple of dogs in the Pentax line.

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    Re: Contax 645 lens curvature issue with MFDB?

    I wouldn't worry about this, no lens is perfect as you can see in MTF graphs. To me the greatest challenge is to nail focus. Even the slightest mis-focus is visible with today's high-resolution sensors. Even shimming a back to the camera is an exercise on the order of micrometers. I have three bodies I use and it is futile to pursue this to the extreme. Life is full of compromises.

    The Contax AF system is said to be very precise:

    From a review: "According to Contax, they have optimized AF precision on three levels. Most AF SLRs on the market use a small number of linear or cross-type AF sensors, usually in a horizontal formation. Each sensor is made up of a few hundred pixels. The Contax 645 is the first AF SLR to use a 1/4 MILLION-pixel CCD for its AF system. The result is a true area sensor (i.e. no gap) with supposedly much higher AF measurement accuracy. Secondly, the AF motor in each lens is optimized for precision with extremely fine movement rather then speed. Lastly, in the case of 220 type films, the vacuum filmback ensures higher film flatness."

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    Re: Contax 645 lens curvature issue with MFDB?

    I posted in that thread that I use a variety of traditional LF lenses with my CFV39 back on my Technikardan 23 with absolutely no problem. I don't shoot wide open but have tested a couple of lenses at max aperture and had no sign of problems. In any case you'll mainly be using the sweet spot in the center of the lens. Even if there was a slight curvature of field most of us live in a 3D world where our subjects are 3D and focus is a compromise anyway. I also use my CFV39 on my 501CM with your standard Zeiss lenses (40 CF FLE, 50 CF FLE, 60 CF, 80, 120 Macro Planar, 180 CF and 250 C T*) and have no complaints about performance.

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    Re: Contax 645 lens curvature issue with MFDB?

    my bad... just mistakenly thought value of paying big bucks for new generation digital lenses to get optimal results from digital backs may have something to do with lens curvature

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