35 mm f/1.8 aperture symmetry « Nikon Rumors Forum

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35 mm f/1.8 aperture symmetry

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JVSPhotos

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I'm relatively new to photography, and just made my first lens purchase beyond the kit lens for my D5000, Nikon's 35mm f/1.8 G. It works great for the most part, but I noticed looking down the barrel that the aperture isn't quite symmetric when it is open most or all of the way. Sometimes one of the blades even pokes its sharp end inside a bit, making the bokeh bumpy. I took pictures of an out-of-focus LED to show you:

Obviously this will not be a factor in the vast majority of photos, but if there are isolated background lights it could be noticeable. The aperture seems to work great otherwise, it goes to whatever size I want it to as far as I can tell.

My question is: is this lens defective, or am I expecting too much perfection from a $200 lens?

Thanks for your help, I don't have enough experience to know what to think about this.

Posted 1 year ago #
Gabbb

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I don't think it's defective. You can easily check it visually, if the aperture blades look normal, or are deformed some way. Also bear in mind, that the shape depends on the light source's shape as well. If you are shooting a light source that's not circular, that can result in something like this. (like led lights rarely are)

Posted 1 year ago #
JVSPhotos

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Gabbb said:
I don't think it's defective. You can easily check it visually, if the aperture blades look normal, or are deformed some way. Also bear in mind, that the shape depends on the light source's shape as well. If you are shooting a light source that's not circular, that can result in something like this. (like led lights rarely are)

Thanks for your input. I shot the LED from about 3 meters away with the focus jammed all the way near. Also the bokeh shape looks just like the aperture, so I'm sure this is real.

Posted 1 year ago #
NSXType-R

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The aperture blades aren't rounded, and there are only 7 of them. That bokeh is normal, check my copy out.

Also, try not to post such large photos in the future.

Stopping down a little helps, but not too much.

Posted 1 year ago #
JVSPhotos

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NSXType-R said:
The aperture blades aren't rounded, and there are only 7 of them. That bokeh is normal, check my copy out.

I wasn't worried so much about the polygonal nature as the pokey bits, but I see the same thing in your second photo, so I guess it's normal. Thanks for posting them!

Also, try not to post such large photos in the future.

Will do.

Posted 1 year ago #
golf007sd

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As NSXType-R has stated your bokeh has to do with the lenes.

NSXType-R said:
The aperture blades aren't rounded, and there are only 7 of them. That bokeh is normal...

+1 NSXType-R

JVSPhotos your 35 1.8 is working just fine. If you want real nice rounded bokeh effect from any lens (prime or telephoto), consider those that have 9 diaphragm blades (ie. 50mm 1.4G).

Posted 1 year ago #
JVSPhotos

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golf007sd said:
As NSXType-R has stated you bokeh it has to do with lenes that have

+1 NSXType-R

JVSPhotos your 35 1.8 is working just fine. If you want real nice rounded boke effect from a lens (prime or telephoto), consider those that have 9 diaphragm blades (ie. 50mm 1.4G).

Sorry, I guess I wasn't clear, I should have annotated the photo. I'm aware that having only 7 blades should make it a rounded heptagon rather than a circle, that's not my concern. It is that the blades deploy asymmetrically, with some of the blade tips protruding into the aperture and not others. Here is the f/2.2 above, first with arrows pointing to the problem spots, then with my sketch of what the blades are doing (I can see this looking at the blades during an exposure):

On the top right, the blades are protruding. On the bottom left, the blades are not and it looks like it's supposed to. You can see the same effect in NSXType-R's 2nd photo (f/2.8).

Posted 1 year ago #
jerl

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Yeah, I definitely see what you mean. That will happen with many lenses, especially the more inexpensive ones. For such a cheap, but well performing lens, they have to cut corners somewhere. Personally, I wouldn't worry about it too much- I suspect that even if you get it repaired, the blades will eventually work their way out of perfect alignment sooner or later. If it really bothers you, I would just stick to shooting wide open.

Posted 1 year ago #
JVSPhotos

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jerl said:
Yeah, I definitely see what you mean. That will happen with many lenses, especially the more inexpensive ones. For such a cheap, but well performing lens, they have to cut corners somewhere. Personally, I wouldn't worry about it too much- I suspect that even if you get it repaired, the blades will eventually work their way out of perfect alignment sooner or later. If it really bothers you, I would just stick to shooting wide open.

Yeah that's what I was wondering. It's still a fantastic lens for the money, so I guess I can't complain!

Posted 1 year ago #
TaoTeJared

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+1 - That is normal. If you pixel peep on any lens, even the $1000+ ones, you can see various imperfection issues. I have found that it never is a indicator if something will go wrong in the future or not.

Realistically on a 4x6 or even a 20x30 you will never see it.

Posted 1 year ago #
golf007sd

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JVSPhotos said:
Yeah that's what I was wondering. It's still a fantastic lens for the money, so I guess I can't complain!

+1 Well put.

Good drawing and good post.

Lastly, welcome to NR.

Cheers....

Posted 1 year ago #
NSXType-R

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I wouldn't be too worried about the aperture blades. I have an early version of the 35mm 1.8, I preordered mine and probably got my copy around April of 2009 and I've used it in snow and light rain and it has been fine.

The 35mm 1.8 was also my second lens after the kit and I've been really happy with the results it has given me.

As performance goes, it's about the nicest bang for the buck G lens for DX. Enjoy your lens!

Posted 1 year ago #
TaoTeJared

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MSMOTO!!!!!

Posted 1 year ago #