Contax G 45mm F2 vs Zeiss lenses

Started Apr 23, 2012 | Discussions thread
ronguo New Member • Posts: 21
Re: So a side question please....

I have owned Rolleiflex, Contax, Canon, Nikon, Leica, Zeiss, and now Sony A7R.  The legacy lens you choose should depend upon your camera: the lens design is the critical factor, not the brand. All brands can make excellent lenses, but not all lenses may work for your camera.

In my case, for the A7R, the ONLY legacy lens designs to use are Planar and Distagon, and of these ONLY the Zeiss.  Avoid Leica for the A7R; they produce pronounced chromatic aberration (magenta shift and other weird colour shifts). Avoid Zeiss Biogon for the A7R, also for CA reasons. Japanese brands may work for you, but you take your chances for CA, unless you can find proper reviews.  I love my Contax G45 lens for the A7R: small, light, portable, and fabulous image qualities. But, it must be used with the Metabones/Shogun adapters ONLY, for it has no focus ring on the lens. This is the drawback to the G series, but it's not really a big deal for use with the A7R. I use the G45 and G90 because I have these from prior years, and they are superb. But were I to start anew, I would choose the DEDICATED Zeiss lenses for the A7R, as these are fast, superb IQ, and mate with the A7R functions precisely with NO adapters, for about the same price as new ZM or ZF2 lenses. If I wanted to save money, I would choose the older Zeiss lenses with focus rings. But now that legacy Zeiss are rising in price, with the added cost of the adapter, the cost savings are not worthwhile.  After my testing, I would NOT choose any Leica lenses for the A7R.

Someone above posted MTF charts. These must be viewed with caution.  For example, the MTF charts for Leica and Pentax are very very close to the Zeiss G (the G 45 is rated as one the ultra best lenses for 35mm film), but they are not Planar designs and the MTF charts are oriented to FILM not digital.  What these MTF charts DO NOT show is the magenta shift you will experience with the Leica and Pentax. MTF is a great tool for black and white, but not for colour digital. You will need to research and test lenses by yourself. The Zeiss lenses all have great MTF curves, but only the Planar and Distagon will not produce CA on the A7R, whereas the Biogon will produce CA. Again, the lens design is the critical factor.

To see results of various lenses for yourself, look into Flickr, but focus your attention upon the FF 24mp and 36mp sensors. Smaller sensors are inadequate for testing FF legacy lenses.

So why do I put up with all the cons for the G45 and G90? Not for price. For IQ and manual operation.  With the G45, I attach it to the A7R without needing in-camera adjustments, lens profiles, or post-pro.  With it, I have total manual control, which is far better for me than relying upon any auto function. The G45 remains unsurpassed for IQ in all respects, except for one other lens: the Zeiss Otus.  The Otus is fabulous, very expensive, but also a real heavy weight that is very fatiguing to lug around all day and night. The G45 gives me fabulous IQ for the purpose I wanted: a light, portable system.  There are very good reasons why G lenses sell today used for about the same price as new long ago.

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