Stupid MF OOF question!

[Debusti Paolo]

Well I know that it may seems a very stupid question....so use patience please...😀 but I noticed that the bokeh of MF Lenses is very pleasant to me (hassy,bronica,mamiya...)although that lenses have "only" 5/6 blades on diaphagmas....Maybe it concern the optical formula?or it's also about format?...🙂Thanks

 

[David William White]

Aperture for aperture, the larger the format, the less depth of field there is. That could be part of it. If you suspect pure optic effects, compare the lenses wide open where the diaphragm blades are fully retracted.

 

[payasam]

For a given angle of view, a lens for a MF camera is of a focal length greater than a lens for a 35mm camera. A "normal" on a MF camera will give the depth of field of a short tele on a 35mm camera. Substantially greater depth of field was touted as an advantage in the early years of the "miniature".

 

[Debusti Paolo]

Thanks! IT caused a bokeh(oof area rendition) that I like.....

 

[Gordon Moat]

The number of aperture blades is only one factor. When you shoot at the widest open aperture, then there are no blades in the optical path; it is just a perfect round circle. Also, if the aperture blades are curved, then they will not affect the defocus rendering.

The optical characteristics of the glass usually have more influence on the defocus rendering (what you called bokeh). Lenses with certain aberations will perform differently. In general, medium format lenses are lower volume production than most 35mm lenses, often implying that they are more carefully constructed. There are obvious exceptions, though in general the performance of many medium format lenses is quite good.

 

[Turtle]

Well I know that it may seems a very stupid question....so use patience please...😀 but I noticed that the bokeh of MF Lenses is very pleasant to me (hassy,bronica,mamiya...)although that lenses have "only" 5/6 blades on diaphagmas....Maybe it concern the optical formula?or it's also about format?...🙂Thanks

A basic rough rule is that when you double the focal length, you need to stop down two more stops for the same OOF look, so when 35mm users complain about not wanting to use MF because of the slow lenses and inability to get the same OOF, they are usually wrong. Speed, because you need the shutter speed is different and MF cameras are of course at a big disadvantage here, especially as you need even higher shutter speeds to avoid shake in some cases.

An example:

Mamiya 7 with 80mm F4 has same rough DOF wide open as a Leica with 40mm f2. Hassy with 80mm 2.8 actually has the equivalent DOF of a 40mm f1.4 wide open.

This is why when you go up to large format you often need such tiny apertures. Up to 5x4 is is not a huge issue, but 10x8 requires another couple of stops as the focal lengths double!

 

[katgut@earthlink.net]

I find that MF does not necessarily mean better OOF areas. The bokeh from my Bronica S2 lenses looks rather busy. My 90 Summicron is much better.

 

[Debusti Paolo]

I find that MF does not necessarily mean better OOF areas. The bokeh from my Bronica S2 lenses looks rather busy. My 90 Summicron is much better.

Maybe because It's a tele lens??