Why not square lenses???

[NateS]

So I was just thinking. The sensor and mirror on a camera are square/rectangular, the image comes out when viewed as a square/rectangle.........so why are lenses round? Wouldn't it seem logical that a lens would be squared? If so, I would think you could get ridiculously wide angle and you would have less problems with vigenetting.

Any thoughts?

 

[Steph]

So I was just thinking. The sensor and mirror on a camera are square/rectangular, the image comes out when viewed as a square/rectangle.........so why are lenses round? Wouldn't it seem logical that a lens would be squared? If so, I would think you could get ridiculously wide angle and you would have less problems with vigenetting.

Any thoughts?

Round lenses are much easier to manufacture?

 

[matt-l]

and use. how would you focus a square lens? or hold it, it would not be comfy at all.

 

[NateS]

Round lenses are much easier to manufacture?

I wouldn't know why. Once they got the process down it shouldn't be any harder. If anything I'd almost think it would be easier. Maybe the bulk, but some of these pros don't care about bulk with their 6 foot long lenses.

 

[NateS]

and use. how would you focus a square lens? or hold it, it would not be comfy at all.

Focus would be easy. Use a push/pull focus mechanism like the older Nikon 80-200 f2.8's.

 

[Garbz]

Missing a big point here. Think of how light bends, and then think of the aperture. Look specifically at 5 bladed lenses. Out of focus light sources are rendered as pentagons. The more blades, the more curve, the smoother the out of focus areas are.

The reason square lenses don't exist are the same reason that mirror reflex lenses are so unpopular. They would just produce a very crap image.

(Logical deduction here. I only assume it works like this. Wait for a Helen comment to see if I'm right)

 

[Battou]

I wouldn't know why. Once they got the process down it shouldn't be any harder. If anything I'd almost think it would be easier. Maybe the bulk, but some of these pros don't care about bulk with their 6 foot long lenses.

I used to work in a steel mill, on the tube mill to be precice. Square tubing is a PITA to manufacture and is actually very low demand in comparison to standard round tubing. Any tube mill manufacturering the square tubing for a square lens would have to be conducting change over a lot. Change over from round tubing to square is a long time consuming task. Resulting in higher prices due to additional labor required to produce. It took our Senior mill opperator sixteen hours to cunduct change over for a thirty six hour run of square tubing where as a diameter change takes a matter of minuets in most cases. just not worth it.

and that is well before you even get to the optics part of it.

 

[Steph]

I wouldn't know why. Once they got the process down it shouldn't be any harder. If anything I'd almost think it would be easier. Maybe the bulk, but some of these pros don't care about bulk with their 6 foot long lenses.

I don't know. My common sense tells me it is easier to spin a circular piece of glass to cut/grind/polish it into a lens element than to do the same with a rectangular one...

 

[snowalker]

and use. how would you focus a square lens? or hold it, it would not be comfy at all.

good point! I've been never thinking like this.

 

[benp2k6]

What shape is your eye? Geometrically speaking a square lens is illogical

 

[nynfortoo]

Isn't some of the glass in a lens concave/convex and almost parabolic?

 

[Antithesis]

What shape is your eye? Geometrically speaking a square lens is illogical

That's my exact thought on the subject, and also, the manfacturing would be far more difficult. Producing a perfect circle is far easier than producing a perfect square.

 

[Bifurcator]

Missing a big point here. Think of how light bends, and then think of the aperture. Look specifically at 5 bladed lenses. Out of focus light sources are rendered as pentagons. The more blades, the more curve, the smoother the out of focus areas are.

The reason square lenses don't exist are the same reason that mirror reflex lenses are so unpopular. They would just produce a very crap image.

(Logical deduction here. I only assume it works like this. Wait for a Helen comment to see if I'm right)

Yeah, aperture apparatus is probably the reason it's not tried. View cameras and even some TLRs have square lenses for framing and stuff. There's the pentaprism too - which at least has corners. I don't think it's the manufacturing that holds it back. I guess it's the function of light like you're suggesting.

 

[tirediron]

Helen... you're needed!

 

[Alex_B]

the aperture should best be round for all shapes of lenses

There are cases of cameras which matte off a rectangle in front of the lens. Mainly to avoid flare resulting from unneeded glass surface i think.

But the lens behind is round again, why? because it is just way easier to produce a rotational symmetric glass object than a random shape with high precision. Rectangular lenses as used for those wearing glasses, are produced round and then cut after they got their curvature.

1. so it is always round first, rectangular cut afterwards -> higher cost

2. but then, if you had a round lens, no element would be allowed to rotate, not even the internal ones -> new lens designs and cumbersome mechanisms for zooming and focusing -> higher cost. potentially also higher weight.

3. then think of the lens barrel, rectangular? again much more cumbersome to produce. -> higher cost. also, a cylinder is much tougher to withstand mechanical forces, so you lose something here.

4. what would the gain be? the lens would not be that much smaller. It would probably not be lighter. But it would be more prone to asymmetrical stress/strain due to mechanical forces and heat expansion. It would be probably a pain to adjust. So image quality might suffer and the lens would be twice as expensive.

Now you decide, if this lens would be on your shopping list