Questions on lens elements and shutter blades


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thenomad

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Nov 17, 2008
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#2
Better lens elements improve image sharpness, contrast and colour. They are also known as ED glass (Extra-low Dispersion).
Basically better quality equals better image capture. The glass captures the image before being fed to the sensor.

Having more shutter blades normally allows you to achieve a more circular aperture opening.
As a result your bokeh (background blur) will be smoother.
If you have a blurred light point, you can see clearly the shape of the bokeh.
Sometimes they are 5, 6, or 7-sided points, rather than a nice round point.
 

giantcanopy

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Feb 11, 2007
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#4
Optics aside, curved blades or more blades can potentially render oof specular highlights in a more pleasing rounder fashion. But that will probably be more of asthetic considerations than IQ.
 

two200

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#5
From the few replies, my understanding is:
- more lens element better IQ cos light 'process' before reaching sensor
- more blades means bigger aperture, hence more bokeh. Hence cannot get same f-no with diff number of blades

So the better lens would be one with more lens element (better IQ) and more blades (better bokeh) if the focal lens is the same.

Correct me if I am wrong
 

Octarine

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Jan 3, 2008
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#6
From the few replies, my understanding is:
- more lens element better IQ cos light 'process' before reaching sensor
So the better lens would be one with more lens element (better IQ) and more blades (better bokeh) if the focal lens is the same.

Correct me if I am wrong
Wrong.
The amount of lens elements is defined by the type of the lens, the optical requirements and the maximum aperture. Compare the structure of prime lenses and zoom lenses and you'll notice some patterns. Also, compare a kit lens (18-55 etc.) and a superzoom (18-270), pay attention to the maximum aperture as well.
 

night86mare

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Aug 25, 2006
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#7
So the better lens would be one with more lens element (better IQ) and more blades (better bokeh) if the focal lens is the same.

Correct me if I am wrong
the better lens is the one that serves your purpose.

if smooth bokeh is not your priority, why would you need more blades? for example, if you buy a ultra wide angle, bokeh is almost nonexistant due to depth of field constraints, unless you focus very close.

but in general.. for lenses in the same class, the above may apply.
 

Oct 18, 2006
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#8
Better lens elements improve image sharpness, contrast and colour. They are also known as ED glass (Extra-low Dispersion).
Basically better quality equals better image capture. The glass captures the image before being fed to the sensor.

Having more shutter blades normally allows you to achieve a more circular aperture opening.
As a result your bokeh (background blur) will be smoother.
If you have a blurred light point, you can see clearly the shape of the bokeh.
Sometimes they are 5, 6, or 7-sided points, rather than a nice round point.
I think you mean aperture blades, shutter blades are those on the shutter, aperture blades control the aperture and the bokeh. Please note the difference (very big difference)
 

Rashkae

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Nov 28, 2005
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#9
From the few replies, my understanding is:
- more lens element better IQ cos light 'process' before reaching sensor
- more blades means bigger aperture, hence more bokeh. Hence cannot get same f-no with diff number of blades

So the better lens would be one with more lens element (better IQ) and more blades (better bokeh) if the focal lens is the same.

Correct me if I am wrong
1. Nope. The amount of elements is dependent on lens design, but in general, LESS glass is preferable.

2. No, the number of blades has nothing to do with the size of the aperture. In general, most new lenses have 9 blades, older ones had 5-7 blades. You can find 50mm f/1.4 lenses with 7 blades and with 9 blades, so the whole "cannot get same f-no with diff number of blades" statement is rubbish.
 

#10
From the few replies, my understanding is:
- more lens element better IQ cos light 'process' before reaching sensor
- more blades means bigger aperture, hence more bokeh. Hence cannot get same f-no with diff number of blades

So the better lens would be one with more lens element (better IQ) and more blades (better bokeh) if the focal lens is the same.

Correct me if I am wrong
Just want to add that in general more lens elements can also be bad in that lens flare is more likely to occur.

This is the reason why zoom lenses which have more lens elements are more prone to lens flare as compared with prime lenses.
 

liarliar

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May 13, 2007
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#11
Wrong.
The amount of lens elements is defined by the type of the lens, the optical requirements and the maximum aperture. Compare the structure of prime lenses and zoom lenses and you'll notice some patterns. Also, compare a kit lens (18-55 etc.) and a superzoom (18-270), pay attention to the maximum aperture as well.
I agree with you. In my perspective cost of lens do not mean more items and materials in the lens assembly means higher cost. In fact less lens less complicated the better the lens. Primes are one good example. They have less moving parts lesser glass elements thus reducing losses in details (aside from a good coat and workamnship) and a lesser chance for the good light to be impaired by a possible bad or poorly manufactured / assembled glass in any of the groups.
 

Snoweagle

Senior Member
Jan 26, 2005
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#13
How does the lens elements affect the IQ and is it better to have more shutter blades?
Usually for the lens elements, depends on what kind are they and what they're coated with that gives u the IQ.

More diaphragm blades will render better bokeh effect as it forms to be more circular. Those with the nicest 'circles' are those with circular blades, as in curved blades to form a near perfect circle.
 

Rashkae

Senior Member
Nov 28, 2005
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#14
So what will be the difference bet the 7-blade 50mm f/1.4 lens and the one with the 9 blades?
Usually, the 9-blade versions result in rounder specular highlights, giving better bokeh.
 

two200

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Nov 19, 2004
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#15
I am asking this question because when I read specifications they always mention number of lens elements in so many grps and sometimes the number of aperture blade. Just trying to understand why the elements and number of aperture blade is mentioned.

For example I noticed that the Canon L lens usually has more lens element than the cheaper lens eg EF 50mm f1.2L has 8 lens elements with 8 aperture blades whilst the EF 50mm f1.8 has only 6 lens elements with 5 aperture blades.

So from the discussions I cleared one hurdle - that more aperture blades gives better bokeh
 

Snoweagle

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Jan 26, 2005
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#16
I am asking this question because when I read specifications they always mention number of lens elements in so many grps and sometimes the number of aperture blade. Just trying to understand why the elements and number of aperture blade is mentioned.

For example I noticed that the Canon L lens usually has more lens element than the cheaper lens eg EF 50mm f1.2L has 8 lens elements with 8 aperture blades whilst the EF 50mm f1.8 has only 6 lens elements with 5 aperture blades.

So from the discussions I cleared one hurdle - that more aperture blades gives better bokeh
That's why it's called 'specifications'. If they leave out all the details, it wouldn't be called that anymore.

U compare the price, built and performance between the f/1.2 and f/1.8 II. It's like comparing a Toyota to a Lambo for example. More blades only makes the circular highlights more round.
 

J-Chan

Senior Member
Sep 21, 2005
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#17
well, at least you'll know how much glass you're getting..
 

two200

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Nov 19, 2004
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#18
U compare the price, built and performance between the f/1.2 and f/1.8 II. It's like comparing a Toyota to a Lambo for example. More blades only makes the circular highlights more round.
Sorry, maybe wrong comparison. How about this comparison: Canon EF70-300 f4-5.6 with 15 element with Tamron AF70-300mm f4-5.6 with 13 element? Just from this specification alone and not from brand name reputation, can any inference be made about which lens is better; akin to comparing computer specs before purchase
 

J-Chan

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Sep 21, 2005
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#19
The keyword here is quality, no. of lens elements gives no indication of image quality.. there are some numbers that can give some indication of image quality, level of distortion, vignetting, chromatic aberrations, and MTF (resolution) etc..
 

Octarine

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Jan 3, 2008
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#20
Sorry, maybe wrong comparison. How about this comparison: Canon EF70-300 f4-5.6 with 15 element with Tamron AF70-300mm f4-5.6 with 13 element? Just from this specification alone and not from brand name reputation, can any inference be made about which lens is better; akin to comparing computer specs before purchase
According your ideas the Canon should win cause it has more elements. Read the reviews and see whether you are right.
Your analogy to computers is also flawed. Whether a system is good or not depends in the purpose. Example: applications not compiled for multiple CPU's won't be faster on a QuadCore CPU. Finally, total performance depends on all components. Small things can make a big difference.
 

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