Bokeh& apeture

[Markok765]

What does the number of blades have in common with bokeh? my uncle has a leica with 11 blades apeture and my lens has 6. the boken is beautiful in the photo he took. my boken is not that good.

Marko

 

[BWGirl]

Well, maybe I am showing my ignorance here, but I always thought bokeh was a function of aperture opening (ie f2.8) rather than blades on the actual aperture. I will be interested to see the responses from people much more knowledgable.

BTW - what aperture settings did you each use?

 

[DirkDynamo]

beat him up and steal his leica. then you have 11 bladed aperture.

bokeh depends on many factors, not just aperture blades. it depends on how wide open you're shooting the lens at and correspondingly depth of field, and of course the optical quality of the glass. the more blades though, the rounder bokeh is in general. remember though that if you use your lense wide open, not stopped down any, then the aperture blades are withdrawn and so number is irrelevant.

and don't forget about what you're actually taking a picture of- the subject is important too!

what kind of camera are you using? i'm sure some people will swear that your uncle's bokeh is so good because he is using a leica, but you can get good bokeh with almost any camera. just open the aperture up all the way!

 

[Markok765]

beat him up and steal his leica. then you have 11 bladed aperture.

bokeh depends on many factors, not just aperture blades. it depends on how wide open you're shooting the lens at and correspondingly depth of field, and of course the optical quality of the glass. the more blades though, the rounder bokeh is in general. remember though that if you use your lense wide open, not stopped down any, then the aperture blades are withdrawn and so number is irrelevant.

and don't forget about what you're actually taking a picture of- the subject is important too!

what kind of camera are you using? i'm sure some people will swear that your uncle's bokeh is so good because he is using a leica, but you can get good bokeh with almost any camera. just open the aperture up all the way!

I am usuing a ashahi pentax sp500 with the 55 1.8,35 3.5, and the 105 2.8

 

[George Papantoniou]

I guess the aperture "roundness" can play a role, but the lense's design (number of groups and elements, aberrations correction etc) must be more important. Things that go on in your mind are even more important. Read the online articles about it. There are interesting discussions on older APUG threads about it (even etymological info on the word "bokeh" by a Japanese wuthority on the subject). Execute a search about it...

 

[Andrey Donchev]

I think that it will be a good idea for you to read the Christopher Perez's comparison test of six lenses found here, and especially his conclusion. In my experience I also find that the number of blades of the aperture, respectively its form has crucial effect on the "bokeh" in the picture.

 

[df cardwell]

Your 105 Takumar ought to be very good.

 

[David A. Goldfarb]

Roundness of the aperture is relevant, but probably not as important as the degree of correction of spherical aberration. An overcorrected lens will often be very sharp, but can have "bad bokeh." Lenses with lots of aperture blades also happen to be older lenses, or in some cases newer lenses aimed at a market that is interested in good bokeh.

Aperture and subject distance are relevant as well. You might find that within a certain aperture range a lens has good bokeh, but it might get harsh when stopped down. The thing is, if you're using a camera where you can see what the lens is doing (i.e., an SLR or view camera), to pay attention to the out-of-focus area at the shooting aperture, just as much as you would pay attention to the subject.

 

[Claire Senft]

Even the location of the diaphragm influences the bokeh effects. A manufacturer makes choices about bokeh during design and manufacturing release. It can end up being a trade off between bokeh and optical correction.

 

[Dan Fromm]

Even the location of the diaphragm influences the bokeh effects. A manufacturer makes choices about bokeh during design and manufacturing release. It can end up being a trade off between bokeh and optical correction.

Hmm. And to think I'd thought that for each lens design, fully specified, there was only one place the diaphragm could be placed.

Was there enough computing power in the universe to all the choices you describe before the mid-'60s? I have the impression that nearly all of the work done when designing a lens is focused on reducing aberrations, getting adequate field flatness, and getting the desired coverage. And, of course, making sure that the design can be manufactured economically.

What does manufacturing have to do with any aspect of lens performance? Either the finished product is near enough to spec to pass QC inspection or it isn't.

 

[Claire Senft]

The capability of manufacturing should be discussed during the design stage so that the designers know that their choices will allow it to be made. Additionally, it is rather naive to believe that something either passes QC or does not. Having more than a 4 decades of employment in manufacturing I can tell you that just because something does not meet specs is no assurance that it will not ship. Besides that taking items that are not in spec and reworking them so that they are is less likely to be as good as making them right in the first place and is certain to lower profit.

 

[Ole]

... Was there enough computing power in the universe to all the choices you describe before the mid-'60s? I have the impression that nearly all of the work done when designing a lens is focused on reducing aberrations, getting adequate field flatness, and getting the desired coverage. And, of course, making sure that the design can be manufactured economically. ...

According to contemporary advertisments, Voigtländer designed the Heliar lens specifically for the best possible transition from sharp to unsharp. The expression was not in use at the time, but as far as I can understand that's what "good bokeh" means.

 

[nolanr66]

The way I understand "Bokeh" is that it is the quality of the out of focus area. It can be pleasant or not so pleasant. Beauty is in the eye of the beholder. To compare you Bokeh to your Uncles Leica Bokeh you need to even the playing field so to speak. Shoot the same film, subject and distance, f/stop and lens length. However some lenses have more pleasing results than others. I believe my Minolta MD lenses provide better Bokeh than my Nikkor lenses. The Nikor lenses are sharper. Take your pick between the two. I prefer the Nikkor lens myself. This is subjective to my viewing. Digital camera's to me have an even grainless out of focus area that is flat and lackluster. Bokeh is dependent on all the qualities of your lens, film, light etc and cannot be pinned down to a single component such as number of blades. . Mirror lenses have a Bokeh of their own with the doughnut shapes they produce.

 

[psvensson]

David is right about the number of blades not being everything. I have a Minolta Autocord with an 8-bladed aperture, i.e. almost round, but the bokeh wide open is almost horrendous. It improves in character as it's stopped down.