Bokeh differences MF RF vs. MF SLR

[brian steinberger]

This topic just came up recently in another thread and it got me wondering myself. What makes the bokeh of say Mamiya RF lenses different than that of a MF SLR (Bronica, Mamiya, Hasselblad)?

I own and use almost exclusively the Mamiya 6 with all three lenses. And I do notice what is sometimes described as a "hard" bokeh with the Mamiya RF lenses. Some say it's "un-pleasing." I think it's unique, and the part of the image that is actually in focus to me appears sharper than SLRs. But why are they different? And what are your interpretations of each?

I'm only interested in talking about the bokeh of MF RFs vs. MF SLRs, nothing else.

 

[David A. Goldfarb]

I think you've got to compare individual lenses rather than the categories of RF vs. SLR lenses.

 

[brian steinberger]

Ok how about the 75 on the mamiya 6 (80 on the Mamiya 7) vs. the 80 on a Hasselblad?

 

[NJS]

no.

 

[Casey Kidwell]

I thought the number of aperture blades was the only significant factor.

 

[Q.G.]

It's not, no.

The degree of correction of in particular spherical aberration, and on what side of 'perfect' the corrections err, i.e. under or over corrected, plays a much bigger role.

Other things will be a factor too; anything that has an influence on how a lens forms an image. So in short: the design of a lens.

 

[brian steinberger]

I'm slow, what are we saying "no" to? Are most rangefinder lenses the same design?

 

[keithwms]

Bokeh is definitely not only about # of aperture blades, though it'd be nice to have slip-in aperture discs! But the whole lens formula and how it is optimized comes into play. There are many factors affecting bokeh, and discussing what makes "good" bokeh has been an inflammatory subject here for quite a long time!

First, bear in mind that high sharpness and contrast are not the best friends of bokeh, when it comes to compact lens design. With their MF RF designs, Mamiya simply optimized for the former. There are several reasons to do this; offhand I'd say compactness might well be the biggest.

The Mamiya RFs grew out of the compact folder concept... they're really not that much larger than a 35mm slr, and f/2 (say) versions of those lens designs would be pretty huge. And if one tried to optimize those (fairly simple) formulas for wide open bokeh at f/2, well, that'd be a task with those simple lens formulas. (Perhaps someone has the lens formula diagrams to illustrate my point?) The lens formulas currently used in the MF RFs would probably need to be abandoned altogether, if you wanted faster lenses and corrections for smoother bokeh. I for one wouldn't want that, I adore the compactness of my mamiya 6es!

I don't find the Mamiya MF RF bokeh especially disturbing, but it's just not the strong suit of those lenses.... and it doesn't typically play any role in how I use the cameras. For people coming from the 35mm Leica/Zeiss world, this is probably the first thing you notice about the Mamiya and Fuji MF RFs, that the lenses are considerably slower, and that you can't shoot tight and close... and so you probably aren't going to have many out-of-focus elements in your composition. For this reason I say that the mamiya RFs are really optimal for documentary / environmental / scenic / landscape compositions, for which you typically wan your context well defined from front-to-back. The compactness figures in there too- you can comfortably take these cameras where those kinds of compositions are most effective.

 

[Q.G.]

I'm slow, what are we saying "no" to?

To "I thought the number of aperture blades was the only significant factor."

Are most rangefinder lenses the same design?

No.

They differ from each other depending on focal length, and on decisions the manufacturer took regarding cost, and on decisions the designer took regarding how to achieve what was asked for.

The difference between short focal lengths FR and ditto SLR lenses is that RF lenses have no restrictions to content with regarding lens to film distance.
So while SLR short focal length lenses have to (no way around it) use a retrofocus design, RF lenses do not.

Longer RF and SLR lenses usually use the same design.

 

[brian steinberger]

This is interesting and has been so helpful. Thank you guys so much!

I do adore my Mamiya 6's as well and use them for all my photography. And while I wish I could get f/2.8 out of the lenses and closer focusing with a wonderful bokeh I'm perfectly happy with f/4 and a decent bokeh.

 

[NJS]

And while I wish I could get f/2.8 out of the lenses and closer focusing with a wonderful bokeh I'm perfectly happy with f/4 and a decent bokeh.

I wish there's some kind of camera system that would do all the tricks I need. Until one comes by I'm obliged to invest in various MF systems to have all of my needs and styles covered... which brings the old joke back: "what it takes to be a millionaire?"