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Smitty
6-Jan-2016, 09:56
I have been reading that images from lenses with a large number of leaves in the barrel will have a different look than an image from a lens with a shutter containing much fewer leaves. Particularly in the area of bokeh.. Is this so??

Steve

vinny
6-Jan-2016, 10:02
yes.

domaz
6-Jan-2016, 10:08
To be fair not all shutters have "fewer leaves". Olders shutters, like Compounds, in particular seem to have just as many leaves as a typical barrel mount.

goamules
6-Jan-2016, 14:45
The shape of the iris can be seen in out of focus highlights, that's all. More leaves have more of a perfect circle, compared to:

http://www.photozone.de/images/8Reviews/lenses/pentax_43_19_k5/highlights.jpg

ic-racer
6-Jan-2016, 14:50
I have been reading that images from lenses with a large number of leaves in the barrel will have a different look than an image from a lens with a shutter containing much fewer leaves. Particularly in the area of bokeh.. Is this so??

Steve
Shouldn't make any difference if you know how to focus and stop down. If you shoot wide open, the number of blades in an aperture makes no difference.

Corran
6-Jan-2016, 15:40
There's a lot of area between f/5.6 and f/32.

Garrett's image shows the octagonal highlights at moderate apertures caused by an 8-bladed aperture. The Copal shutters have seven or five (older/smaller) blades and will do the same thing with a corresponding difference in sides to the shape.

This also effects the rays of light which show on a point light source, such as street lights. The # of blades = the number of rays in the "star" when even, or when odd, they are doubled (i.e. 7 blades, 14 points while 8 blades would make 8 points).

More blades = smoother circle at moderate aperture but also lenses can have curved apertures to do the same thing with less blades.

djdister
6-Jan-2016, 16:05
It's not barrel vs. shutter, and "the look" is not just from the shape of the aperture. The nature and degree of spherical or chromatic aberration in a lens design, in addition to the shape of the aperture, combine to have a strong impact on "the look" of the recorded image. There are probably other optical reasons which influence the look on film too, like the number of air-to-glass surfaces, but it isn't just a barrel vs. shutter issue. I have a lens in shutter which has many aperture leaves and is just as round as any aperture in a barrel lens.

Corran
6-Jan-2016, 16:12
I could be wrong, but I assumed the OP was talking about an identical lens set in a barrel vs. a shutter. In which case the characteristics of the lens itself is not in play, unless the barrel and shutter have a grossly different length between lens cells.

Oren Grad
6-Jan-2016, 16:43
The shape of the diaphragm and the mix of optical aberrations combine to produce the OOF rendering. Harold Merklinger wrote an article that explains this nicely:

A Technical View of Bokeh (http://www.trenholm.org/hmmerk/ATVB.pdf)

Ken Lee
8-Jan-2016, 11:01
http://www.kenleegallery.com/images/forum/roundaperture.jpg

This photo was made with an old Tessar, stopped down to f/8. The lens is mounted in an old shutter. It is not barrel-mounted.

It doesn't matter in every photo, but for certain subjects it's nice to have an aperture which appears round at all settings.