 CHARLES W. SWENSON |
What is the advantage of a 72mm lens vs a 52mm len Is there a significant advantage using a lens with a 72mm opening vs a 52mm opening? Or any in between. What does the size of the lens opening(filter size) have to do with the lens itself?
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Alan N. Marcus |
Hi Charles, The numbers you are asking about pertain to the diameter of the filter accepted by your camera lens. To attach filters, we generally screw them directly into the front end of the lens barrel. Naturally, we want the filter to fit so we purchase filters that are correct as to diameter and screw thread size. We particularly want to avoid mounting a filter that is too small. Remember, the camera lens is peeping out at the world through the filter. If the filter is too small, the outer corners of the image the lens produces will vignette, meaning a too small a filter interferes and the corners of the image will be lopped off. Thus it is better to mount a filter that is too large vs. one that is too small. That the answer to your question. Now for stuff you didn't ask for... Generally, we buy screw-in-filters that are uncomplicated as to mounting. However, if you have an arsenal of lenses you might choose to buy filters that mount easily to the biggest. Thus you will need adapters (step-down) rings and the like. The filters you are familiar with are glass-disks made with high grade optical glass. A good filter must be an optical flat. This means both sides are flat and parallel to each other. Optical flats are most difficult to make. Large optical flats are costly to make. Additionally, the mount must position the filter square with the camera lens barrel. There are other forms of filters. Professionals sometimes require specialty filters; often they are square in shape and require special adapters to mount them. Some filters come as an optical glass sandwich, two glass disks with colored gelatin in the middle. Some are gelatin squares, lacquered for protection, some are hard plastic like acrylic cut into squares or circles or rectangles. In olden times we purchased mainly the sandwich filters. They were disks with no screw threads. They came in sizes labeled Series 4, 5 and 6 etc. We needed an adapter ring to mount them to the camera lens. Additionally we needed a retaining ring to hold the filter and step-up and step-down adapters, in other words, you have it easy, enjoy the ride. In short, better an over-size filter to avoid the vignette. Alan Marcus (marginal technical gobbledygook)
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Bob Cammarata |
Quite simply... Large diameter lens barrels are "faster"...letting in more light than smaller diameter lenses of the same focal length.
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W. |
LOL!, Bob! :–)))
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John P. Sandstedt |
The lens manufacturer goes to the lens design guru and says, "I want to produce a lens that does the following . . ." The lens designer goes to his Ouija Board [or some other kind of computer] and works out what's needed in the way of: He might also ask the manufacturer about weight restrictions, camera[s] on which the lens will used with, etc. And, then he presses the Start Button [or Enter Key.] The Ouija Board whirrs and whirrs and comes out with a solution that says, "Assuming your customer will accept a variable aperture zoom lens, make the item using X elements, Y motor functions, etc. It should be X inches long and weigh Y ounces and, oh yes, have a final ring that that will accept a 52, 55, 62, 67, 72, 77 or some appropriate filter size that works with the camera's sensor size. Wow. In my opinion, there's absolutely no advantage using a lens with a larger filter ring size. If the lens is well designed, and fits your camera, you'll get the designer's intended results. I have the first iteration Tamron 28-200 mm zoom lens [for film cameras] that accepts a 72 mm filter. The next three generations came accepting 67 mm filters. From a comparative standpoint [for the vast majority of us amateur/ advanced amateur photographers] there was little difference in quality. Moving to the digital world, my Canon 30D accepts my Tamron 28-200 [72 mm filter size] and my Tamron 200-440 [77 mm filter size.] My Canon 17-85 mm IS zoom accepts 67 mm filters. My son, who also has a 30D has the Tamron 18-250 mm zoom that accepts 62 mm filters. All of these lenses have a variable aperture range of about f/3.5-5.6. It's the focal length of the lens linked to the aperture [diaphragm opening] that determines the total light that reaches film or sensor. It's NOT the outermost piece of glass on your lens. I recommend that you forget the filter dimension and consider f-stop [fixed or variable] and your desired focal length range relative to your budget. Stop worrying about filter dimension.
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Pat Harry |
Alan, continuing with your response... Is that where a Coker system comes in? To allow us to use one filter for all the different size lenses we have? I want to get a good polarizing filter, but I'm hoping to avoid buying one for each of my lenses, since they are different sizes. I think I understand that a Coker will fit all the lenses, and the filter slips into it. Correct?
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Oliver Anderson |
John said, "In my opinion, there's absolutely no advantage using a lens with a larger filter ring size. If the lens is well designed, and fits your camera, you'll get the designer's intended results." But I've found that the larger the lens the more Cool people think you are and it really helps to work your bicep up if its big and heavy... I think Alan, Bob, Will & John will agree with that.lol On one note it is nice that Canon made several lenses 77mm so you don't have to buy tons of filters in different sizes, I can swap between my 17-40, 24-70 & 70-200.
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Alan N. Marcus |
Follow this link: http://www.geocities.com/COKINFILTERSYSTEM/howitworks.htm Cokin is a first class filter maker. The polarizing screen (filter) is the most important filter to have in your arsenal. It subdues reflections from non-conductor materials. Two types: Best in linear but this design may fail on some cameras that utilize polarization in the auto-focus or exposure sensor mechanism. Slightly wanting is the circular. A sandwich filter. First a linear polarization screen to do the job (and it does just that) followed by a filter that scrambles polarized light (de-polarizes) so cameras sensitive to polarization are not harmed. Only problem is extra surfaces can add flare. Alan Marcus
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Alan N. Marcus |
If I had an arsenal of lenses, I would attempt to mediate the cost of filtering them. To accomplish I would outfit the biggest diameter with filters. Then, to accommodate others that accept smaller diameter filters, I would procure necessary stepping adapters. The idea is to save some money. Let me add that I think each lens should be fitted with a lens shade. The filters I would choose would be coated. A coated filter reduced reflections thus minimizing flare. Flare is devastating to an optical system. Let me add, sometimes a camera mounted with huge filters and sun-shade and adapter rings looks like a disaster. Cameras and their accessories are the tools of the trade. If they look ridiculous it can spoil your image. Alan Marcus
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