number of aperture blades

[maitani]

I just seen a picture of the rare old 85 1.5 Nikon rangefinder lens, and if I counted right, the thing has 16 (!) aperture blades, a true masterpiece in the art of handcrafting.
It’s a spectacular looking lens. I also notice that the old 5 cm 1.4 sc lens has 12 aperture blades, where the newer 50 1.4 multicoated design seems to have 9 aperture blades.

Any thoughts on this?

Most Nikon F mount lenses, for example Ai lenses have usually 7 blades, most Ai/S lenses have 9 blades for more rounded closing, and therefore smoother ‘Bokeh’.

Is there a particular reason for the extensive number of aperture blades on those older lenses like the 85 1.5?

Or is it just for economic reasons that the actual ‘industrial standard’ is 7 or 9 blades? Is there any drawback on too many aperture blades?

Is there any comprehensive list on the web where I can check about the number of aperture blades on nikon RF lenses?

 

[kmallick]

The Leica Elmar 50mm f/2.8 has 15 blades and I love it for the nice rendition of the oof areas.

I am assuming assembling the high number of aperture blades in a lens is as much of a mechanical design challenge as economics.

 

[ChrisP]

In general it seems that RF lenses have more blades than SLR lenses. I assume this is because with a rangefinder the blades only move when you change aperture but when using an SLR the blades constantly move (every time you take a picture they have to close down and than open up again very quickly), so its probably easier to put more aperture blades on a RF lens

 

[mahleu]

My 9cm Elmar has a lot. One day i'll manage to get them all back in correctly. A day when i'm more patient...

 

[ampguy]

More blades enables you to get closer to a perfect circle than less blades. The closer to a perfect circle, the less diffraction.

Bokeh may be another reason.

The best bokeh of the CV lens that I have seen is the 35/1.2. It has a lot of blades.

The best bokeh of a 50mm lens I've seen is the old Elmar 50/2.8. It has a lot of blades.

 

[Phantomas]

More blades enables you to get closer to a perfect circle than less blades. The closer to a perfect circle, the less diffraction.

Bokeh may be another reason.

The best bokeh of the CV lens that I have seen is the 35/1.2. It has a lot of blades.

The best bokeh of a 50mm lens I've seen is the old Elmar 50/2.8. It has a lot of blades.

That's correct. One more thing worth mentioning is that modern lenses use rounded aperture blades to come as close to the perfect circle as possible. This partly negates the need for more blades.

 

[mgilbuena]

I've noticed a lot of older glass seems to have more aperture blades. This results in very smooth transitions as one opens up and sees naturally rounded points of light.

Out of curiosity, is there a compiled list of all rangefinder lenses and the number of aperture blades they each have? I would be interested to see what lenses have 10 or more blades.

 

[raid]

The old Rollei QBM SLR lenses 35mm and 85mm/1.4 have three blades.

 

[thompsonks]

The Leica Elmar 50mm f/2.8 has 15 blades and I love it for the nice rendition of the oof areas.

Goodness, my Elmar-M – the last model – has just six! I didn't think Leica would 'dumb down' a product like that. The blades seem, however, to have rounded/concave ends, which may give somewhat the same result.

PS: I found a nice picture of the 16 blades (with some oil or wear on them) over here:
http://www.getdpi.com/forum/gear-fs-wtb/45535-fs-elmar-summaron-2-8-a.html