Lens Barrel size question

[koolkat]

When looking at lens, I seem to check a number of things. Maximum apperture size, focal length, weight, reviews on the lens & price. One item that I may pay very little attention to is the "filter size" or barrel diameter. I've studied a number of lens in my brief ownership of DSLRs and notice that some of course are 52mm / 58mm / 72mm and wonder what those "measurements" have to do with lens quality or the selection of one lens over another. In other words, why do some lens have one size barrel diameter and others have a different diameter. In review of several lens, maximium apperature size may come into play. Such as Canon's 70x200 F2.8 is 77mm while the F4 is 67mm but the 70x300DO F4.5-5.6 it is 58mm. And, would a larger diameter barrel have a wider view of the picture. If one were to set up two lens and all things being equal except the barrel diameter, would the larger diameter have a larger "picture".

[Dave Humphries]

When looking at lens, I seem to check a number of things. Maximum apperture size, focal length, weight, reviews on the lens & price. One item that I may pay very little attention to is the "filter size" or barrel diameter. I've studied a number of lens in my brief ownership of DSLRs and notice that some of course are 52mm / 58mm / 72mm and wonder what those "measurements" have to do with lens quality or the selection of one lens over another. In other words, why do some lens have one size barrel diameter and others have a different diameter. In review of several lens, maximium apperature size may come into play. Such as Canon's 70x200 F2.8 is 77mm while the F4 is 67mm but the 70x300DO F4.5-5.6 it is 58mm. And, would a larger diameter barrel have a wider view of the picture. If one were to set up two lens and all things being equal except the barrel diameter, would the larger diameter have a larger "picture".

Hi Mike,

To answer the last bit first; no - it isn't that simple.

The focal length figure determines the angle of view for a given camera body (and hence sensor size)
A 28mm lens (on a certain camera) will give a certain angle of view.
If you have two 28mm lenses, one that has a maximum aperture of f/4 and one of f/2.8, the latter will have the larger diameter lens barrell, but the picture you see will be the same on both lenses.

The diameter of the filter thread (the measurement you refer to) is dependent upon the aperture, focal length AND lens design - just look at the front of some lenses and the front element goes right to the filter thread while on others there might be a significant circle of plastic between the two.

Rules of thumb;
Larger maximum aperture will give a larger filter (and lens barrel) diameter - as example above
Shorter lowest focal lengths will also give a larger filter (and lens barrel) diameter - e.g. a 55-200mm is more slender than an 18-200mm lens if both are say f/3.5-f/5.6.

Cheers,

[krispix]

Wow! That's some question.

The answer is 'No' - Sort of. A lens will enscribe a circular image, the manufacturer will then 'crop' a section from the centre of this. How large this crop is depends on a number of factors. As you get further out from the centre the light value falls off, as does the quality, so they will crop out as little as they can get away with and still retain a fairly even light distribution and image sharpness. A cheap lens may exhibit a noticeable loss in the corners because they tried to squeeze too much out of it. So, the barrel diameter is not the sole arbiter of the lens speed (or max. aperture). You will find that more expensive lenses tend to be larger, both in length and diameter, they will also be heavier (more glass) than a cheap lens with the same characteristics. Again, more expensive lenses may have more glass strung together in more elements. The more glass you have the greater the light loss and the greater the barrel and glass diameter will have to be to maintain a large aperture.
Like everything in life, photographic equipment is a compromise. The manufacturer will weigh up what he can sell and that is dictated by what the buying public want and how much they're prepared to pay for it. Certainly, you could have magnificent optics, and a very fast lens, but would you pay the price and be prepared to shoulder the weight? Generally speaking we tend to look for the best quality that we can afford and if we can squeeze a little more out of the piggy-bank we'll go for speed too.
I hope I've answered your question, unfortunately it's not one that can be resolved with a simple 'yes' or 'no'.

EDIT. Dave slipped in there while I was compiling my response. He's probably explained it better, but it is not a simple matter.

[Colin Southern]

When looking at lens, I seem to check a number of things. Maximum apperture size, focal length, weight, reviews on the lens & price. One item that I may pay very little attention to is the "filter size" or barrel diameter. I've studied a number of lens in my brief ownership of DSLRs and notice that some of course are 52mm / 58mm / 72mm and wonder what those "measurements" have to do with lens quality or the selection of one lens over another. In other words, why do some lens have one size barrel diameter and others have a different diameter. In review of several lens, maximium apperature size may come into play. Such as Canon's 70x200 F2.8 is 77mm while the F4 is 67mm but the 70x300DO F4.5-5.6 it is 58mm. And, would a larger diameter barrel have a wider view of the picture. If one were to set up two lens and all things being equal except the barrel diameter, would the larger diameter have a larger "picture".

Hi Mike,

Focal length divided by max aperture = lens diameter, but keeping in mind that we're talking about the optics here, not necessarly the "whole thing", but obviously there's a loose relationship between them (eg a 600mm F2.8 would by definition have a larger diameter than a 600mm F5.6).

There isn't really a quality relationship per se -- just this morning I've been shooting artwork for an artist (http://www.bellamygallery.co.nz/ <- shameless plug for Michelle!) - and my "weapon of choice" was a TS-E 90 with the smallest diameter of all of my lenses - but it has lethal sharpness.

[Donald]

Sorry - Diversion

just this morning I've been shooting artwork for an artist (http://www.bellamygallery.co.nz/ <- shameless plug for Michelle!) .

Did you do the stuff that's on her site at the moment?

By the way, her work is very good.

[Colin Southern]

Sorry - Diversion

Did you do the stuff that's on her site at the moment?

By the way, her work is very good.

Hi Donald,

I have no idea to be honest - Since I get to see her work "up close and personal", I haven't actually looked at Michelle's site for a while.

She's always painting new pieces, also sells limited print editions (in addition to the originals) - so chances are there will be more and more of my reproductions on her site shortly (she's finishing an exhibition in a week or so, and I have to photograph all of the current paintings then). For the most part, my involvement is the photographing & post-processing, and then I print the limited editions which Michelle then has framed and mounted.

We've spent quite a lot of time chatting whilst waiting from prints to pop out of the printer -- it's quite funny when one starts to appreciate the difference between photography and "real artists"

[inkista]

Just a visual aid on how max. aperture might affect barrel diameter, but also may not:



All three are 50mm lenses. From left to right, they are the OM-mount Olympus Zuiko 50mm f/1.8, the Canon EF 50mm f/1.8 II, and the OM-mount Olympus Zuiko 50mm f/1.2. The filter sizes on the three lenses (again, from L to R) are 49mm, 52mm, and 49mm.

The larger maximum aperture of the f/1.2 lens makes it obvious that there are larger glass elements in it, and that the barrel might very well have been designed to be larger to accommodate them. But the reason the EF 50mm f/1.8 II actually has the larger barrel and filter size is mostly because a focus motor had to get jammed in there. The two Zuikos are both manual focus lenses, and Olympus puts a design premium on making small lenses.

So, yes, a larger max. aperture often creates a thicker barrel in a lens, but it's not a hard and fast rule.

[koolkat]

I really want to thank all those that answered, read my question. I'm always amazed at the wealth of knowledge that is so freely shared to help those of us somewhat new to the art & take a look at a question in another, different view.

[krispix]

I really want to thank all those that answered, read my question. I'm always amazed at the wealth of knowledge that is so freely shared to help those of us somewhat new to the art & take a look at a question in another, different view.

That's what we're here for Mike.