IQ difference between Mamiya RB/RZ lenses and Pentax 67

Discussion in 'Medium Format' started by Electrodist, Apr 13, 2019.

  1. Hi, would anyone have input as to the image quality difference between Mamiya 67 lenses and Pentax 67 lenses? From examples on Flickr and Instagram it looks like the Pentax lenses tend to have more macro contrast and a more abrupt falloff of focus, creating a more pronounced 3D effect. The Mamiyas to my eye seem to look less punchy, with a lighter touch in resolving fine detail, and a gentler fall off of focus. Does this line up with the working experience of others?
  2. I have a decent amount of experience with the RB67, and none with the Pentax.

    As an idle thought, though-you comment on the apparent focus fall-off. This really is a function-in any system and format-of magnification ratio and aperture. In many cases, Pentax lenses are a stop faster than the comparable lens in the RB system. The "standard" 90mm lens is f/2.8 for the Pentax, and f/3.8 or f/3.5(depending on generation) for the RB. This is the fastest lens for the RB67 system, while Pentax lenses get as fast as f/2.4. I think there are two factors at play-first of all, while there are leaf shutter Pentax lenses, most are not, and the leaf shutter limits the practical speed of the Mamiya lenses(you see the same thing in Hasselblad, where lenses for the focal plane system can be a stop faster than the more common leaf shutter lenses). Also, the revolving back necessitates a larger image circle-you need to actually cover a 7x7 frame-which means more light fall-off.

    I've found the RB lenses(I have 6, ranging from pre-C to K/L) to be generally excellent, although the K/L lenses certainly have a big more contrast. They also seem to have an edge in sharpness, although you have to remember to set the CRC properly. Truth be told, though, there are very few BAD MF lenses from the major makers.
  3. The limiting factor is the photographer.
    Stephen_Prunier likes this.
  4. +1
    this 6x7 stuff was made for pros, each lense costing lot of $,
    Stephen_Prunier likes this.
  5. ben_hutcherson covered most of the bases on this quite well.

    I would just re-emphasize what dramatically different camera systems these are: night and day in some respects. You don't choose between them over lens rendering: you choose because you need the operational strengths of one system over the other. Lenses are a distant second consideration.

    Do you prefer handheld, grab and go, prism viewing, jumbo 35mm SLR handling? Do you have little to no interest in fill flash? Then the Pentax is more likely to suit with its optimization for small prism & handheld + some faster lenses.

    Do you far prefer waist level or high magnification viewing to prisms? Do a lot of tripod-mounted or studio work? Do a lot of shots that require daylight fill flash? Then the RB67 is your tool of choice. The unique rotating film back makes this the coolest waist level camera ever, all lenses have leaf shutters for easy fill flash.

    Other factors come into play that aren't as obvious. The big heavy clumsy-looking Mamiya can be quite nimble for hand-held use, depending on lens and how you personally get along with its ergonomics. The leaf shutter combined with heavily damped mirror make low-light handheld shots at 1/60 or even 1/30 possible with practice, and the bellows focus knobs on either side of the camera can make finding focus quicker than wrapping your hand around a big lens helical on other cameras. Annie Leibowitz shot a number of her famous portraits with handheld RB/RZ.

    The Pentax is very clearly designed for handheld use, but in some perverse respects isn't as usable handheld as the Mamiya. The huge focal plane shutter can be tough to hold sharp below 1/125, portrait orientation can be awkward. In bright daylight street photography, or custom fill flash or studio lighting that can sync at high focal shutter speeds, its fantastic: below 1/125th, not so hot sometimes. Some users also complain of shutter shock even when tripod mounted. The Pentax was the most popular medium format system for tasks like aerial photography back in the day: if you have good light, its delivers awesome detailed images.

    Most of the Pentax SMC lenses are multicoated with modern (for the '70s/'80s) coatings: the newest SMC Pentax series usually being the best. A large percentage of the Mamiya glass still in use is either not multicoated, or has multicoating that is primitive compared to Pentax. Also, Mamiya was anything but consistent in quality control across their many MF lens systems until they finally got their act together in the mid to late 1980s. Sample variation of RB lenses can be a problem, esp the oldest most affordable lenses with flared front barrel. The final K/L updates had the highest optical quality, esp the wide angles, compared to earlier versions: these are more directly comparable to the newer Pentax glass.

    So if you want the most "modern" microcontrast, you want the latest glass for either system (Mamiya K/L or SMC Pentax). Anything older (Mamiya without a red "C" in the name, Pentax labeled Takumar) may or may not render the way you want. Some prefer the older glass for artistic reasons: obvious snap and bite (esp for portraits) isn't always desirable.
    Last edited: Apr 15, 2019
  6. Silent Street

    Silent Street Silent Street Photography AUS

    Don't let yourself be too influenced by what you are viewing on a computer screen. Who is to tell how much an image has been altered/improved/modified or otherwise contrived from its original conception?

    How old are RB lenses? Decades old. And which ones are you referring to specifically? You cannot paint them all with the one and same brush. That said, how well the equipment performs also comes down to how well you know your lenswork.

    The Pentax 67 (this refers to the 1990-era releases designated SMC Pentax 67, lenses maintain a somewhat dated internal structure (time-proven Distagon and Biogon) but add a number of snazzy (and expensive!) flourishes in the updates in the opening years of the 1990s. ED glass in the 400mm SMC Pentax lens and double aspherical elements in the 75mm f2.8AL are but two stand-out examples -- , both pretty much the priciest and most sought after in the Pentax 67 stable. Both these lenses mentioned have beautiful contrast and astonishing clarity, but you do pay for this and many people cannot justify the expense when there are comparable lenses e.g. the 75mm f4.5 and 75mm shift lenses, though heavy and dated even by recent release standards. The lovely 75AL has a feathertouch, spring-loaded aperture dial, precise focus and aperture blades that must be seen to be appreciated -- a perfect circle.

    Old Pentax Takumars are not on the table as a recommendation.
  7. You don't care for the 105mm 2.4?
    Considered by many as the very creamy bokeh lens.

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