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Home >> Photography >> Accessories Canon 500D
Close-up Lens Attachment Sooner or later a serious photographer will try his or her hand at macro photography. Macro photography is usually associated with photographing very small subjects, such as insects or flower buds; however, macro photography can be applied to just about any subject matter because technically it is just magnifying a subject to a certain standard. Most lenses can only magnify to about a 1:10 ratio (the Nikkor 50mm f1.8 AF does slightly better at 1:8). The first "1" signifies the nominal value of the film or capture device and the second number represents the fractional value vis a vis the subject's actual size, or in other words, a 1:10 ratio means the subject is 1/10 its actual life size on film. As the number becomes smaller, such as 1:4 or 1:2, the subject is being magnified more and more and 1:4 represents the subject being 1/4 its true life size while 1:2 represents the subject being 1/2 its true life size. A 1:1 ratio represents the subject being its actual life size on the piece of film and is the standard that most macro photographers want to work with. We should first clear up some of the terms before proceeding. I'm going to call the magnification up to 1:1 "macro" because it is now accepted convention to do so, but technically this is not macro photography. Macro photography is using a very, very large camera to take photos of very large subjects to produce billboard-sized enlargements. What is now known as "macro" photography is actually photomacrography, which is taking a photo of a small subject and magnifying from life-size to larger than life-size, up to probably 20:1 (20 times life size on film). Going past this magnification and we're getting into photomicrography, which is using microscopes to take photos of tiny subjects. In a curious twist Nikon's highly acclaimed photomacrography lenses are called "Micro" lenses by the company, whereas all the other major brands call their macro lenses "macro". If you want all the gory details about macro and all the theory behind them, I recommend John Shaw's book Close-ups in Nature . It's dated and some of it is repeated in his other books, but it will provide the basic foundation for understanding macro photography. Now, if I wasn't such a cheapskate, or rather, if I wasn't so damn poor because I spent all my money on other photographic things, I would have owned a macro lens by now. Actually I did own a manual focus Nikkor 200mm f4 micro lens that went down to 1:2, for a brief period of time, but sold it off in a fit of consolidation and repudiation for anything manual focus with my primary 35mm Nikon kit. Since then I have desired to add a 1:1 capable macro lens to my kit, but just never found that spare $1000 CAN lying around to buy the 105mm f2.8 Nikkor.
I could have compromised a bit and probably have found $600 for the 60mm f2.8 Nikkor by now, but I'm not thrilled with the scant 4 inches of working distance the lens provides. This is not to say that the 105mm is all that much better with its 5.5 inches of working distance (a mere 1.5 inch improvement); however, the 105mm can be used as a regular telephoto portrait lens, something that a 60mm lens does not do as well. There is also the 200mm f4 Nikkor that offers 10.5 inches of working distance, but this lens is priced in the lower $2000 CAN range and is out of my budget for a specialty lens that would not see a lot of use to justify its price. Lastly, there is the Nikkor 70-180mm f4.5-5.6 Micro zoom lens and the very intriguing 85mm f2.8 Tilt-Shift lens that goes down to 1:2, but these are also beyond my limited budget. All this talk of working distance, but what does it exactly mean? For the figures listed above, working distance is measured from the front of the lens to the subject and is different than the closest focusing distance of the lens, which is measured from the film plane to the subject. Although the 200mm f4 lens has a closest focusing distance of half a meter, its physical length reduces the working distance to about half that distance. Working distance is important to note because there are times when getting close to your subject is not particularly beneficial for your health. How close would you like to get to a poisonous snake for the sake of a photograph. Personally, I'd prefer using the safety of a 600mm f4 lens with its minimum focusing distance measured in feet, not inches for such critters :-) Also, working distance allows you greater flexibility for lighting the subject. Get into within inches and how much light will there be for the subject and having to stop down for depth of field often means having to use flash and risk blowing out the highlights if your flash is too close in. A generous working distance allows the use of reflectors for natural lighting and with jittery insects, less risk of having them take flight as you approach them. With a desire to do some macro-range photography without the budget for a real macro lens, what's a photographer to do? Well, a couple of options are available that will cost a lot less than a macro lens, but with some compromises. Extension tubes offer a reasonable alternative at modest cost, especially if you buy used or find a good deal on third-party products such as from Kenko with their Auto tubes. The advantage of Kenko's Auto tubes is that they offer metering and even auto focus with their tubes. A set of three consisting of 12mm, 24mm, and 36mm tubes is available and I use to own a set and still wonder why I was so stupid to sell them off. The basic theory with extension tubes is that for 1:1 magnification, you need the same number of mm of extension as the lens you are using, e.g. a 50mm lens would need 50mm of extension in order to achieve 1:1 magnification. Obviously, the longer the lens you use the greater the extension you would need and going past a certain number results in an unwieldy amalgam of lens plus extension tubes. Unfortunately, it isn't as simple as just using a 24mm wide-angle lens with a 24mm extension tube to achieve 1:1 either, since your working distance will be virtually non-existent. Teleconverters can also be used with extension tubes to add extension without actually having all the physical mm needed. For example, if you were using a regular 100mm short telephoto lens, you would need 100mm of extension to achieve 1:1 magnification; however, by attaching a 2x TC to the camera first, you can reduce the 100 mm of extension to 50 mm and still have 1:1 magnification, because the 2x TC doubles up the physical extension just it doubles up the telephoto reach of a regular lens. Extension tubes also cost in terms of light transmission. Tubes may be nothing more than empty air between the lens and the camera, but that empty air robs you of light and costs you in f/stops. Couple that lost of light with the usual need to stop down the lens significantly in order to maintain depth of field and macro photography with tubes can be a life of very slow shutter speeds. If you're into taking photos of wild flowers in their natural habitat, the wind on even a calm day will be your biggest enemy and will result in either motion filled flowers or ones with very little depth of field, as you try to eke out as much shutter speed as possible. I had to do mental gymnastics to calculate how many f/stops of light I lost whenever I used my Bronica kit with a 2x TC and 36mm extension tube with my 80mm lens to achieve 1:1. Ah yes, depth of field. The closer you focus in and magnify the subject, the less depth of field you will have to work with. In general photography, depth of field is usually measured in feet unless you work with super fast telephoto lenses wide open, in which you will be counting the inches the same as with macro photographers (e.g. Nikon's 85mm f1.4 and Canon's 85mm f1.2 short telephoto lenses). When you start working with true macro ranges such as 1:4 lenses through to 1:1, you may start with inches, but quickly end up counting in millimeters with tiny adjustments in lens placement making the difference between a keeper or a trash bin filler. If you can afford it, a focusing rail or sliding bar attachment, such as the Manfrotto 454 Micro Positioning Plate, to be placed between the camera/lens and the tripod head is nice to have, as this allows you to more easily obtain the optimum macro focusing distance. Kirk and Really Right Stuff also make similar, but very expensive products for the Arca Swiss ball head users. The alternative to the extension tube is the close-up lens. I use to call it a filter, but a filter implies effecting the scene by way of embellishment or other controlling fashion to saturate colors or hold back contrast whereas a close-up lens affects nothing but the close focusing ability of the master lens. Close-up lenses are clear and as such do not affect the exposure like extension tubes; however, they are like filters in that they screw onto the front of the lens like any other circular filter. Most close-up lenses on the market are single-element types, which are quite affordable, but are not necessarily the last word in quality. If you want a close-up lens that can come close to the quality offered by a true macro lens you need to look at the dual-element, achromat types. An achromat lens is made up of two elements (sometimes more) cemented together to provide for control of chromatic and spherical aberrations. The two elements have opposite properties and when put together complement each other. It is perhaps no coincidence that the dual-element achromat close-up lenses are usually recommended for use with telephoto lenses, which can suffer from chromatic aberrations without the use of extra-low dispersion elements. Hardcore optical theory available here. Nikon has three dual-element achromats available, but I chose not to buy any of them because the maximum diameter offered is 62 mm with the 6T. The lens I wanted to use a close-up lens with is my 70-200mm f2.8 VR lens and thus I needed a close-up lens in 77mm diameter size and over and over again, I have heard very good things about Canon's 500D. Thus it was recently that I stopped by my local shop of Broadway Camera and ordered one in. My man Henry Wong, seemed a bit incredulous with this order, as he looked at me and asked again, "You want to spend $250 on a close-up lens?" He suggested that I just spend a bit more and buy myself a Tamron 90mm f2.8 macro lens instead. It was an intriguing thought since the Tamron is considered to be amongst the best if not the best third-party macro lens available and usually selling for about $600 CAN. Then I thought about my Tamron 20-40mm lens sitting forlorn and abandoned on Broadway Camera's used shelves, as I attempt to sell it on consignment. Third-party lenses sell very slowly and for much less than a prime brand's products and I'm pretty certain that owning a Tamron would not stop me from wanting to own a Nikkor, no matter how good the Tamron is. Hell, having the very good Tamron 20-40mm did not stop me from buying the Nikkor 18-35mm lens, so no need to travel down that road again. I passed on the Tamron and confirmed the Canon 500D, which can do double duty with my Bronica medium format kit too.
Although I have the 500D attached to a B+W filter in the image at right, this is for comparison purposes only, as I would use the 500D directly with the lens only and any additional filters, such as a polarizer would go on top of the 500D. Below are some quick samples comparing the maximum magnification of the 70-200 lens on its own, with a 2x teleconverter, with the 500D and in combination with the 2x TC. The first set of tests are with a Canadian 25 cent coin, which is the same size as the American quarter. D100 digital camera set for RAW capture used, with the RAW files converted via Adobe Camera RAW in Photoshop 7 and 300% USM applied for all samples. What did I notice? Using the 500D alone with the 70-200 lens provides very nice results and although the 500D with the 2x TC provides greater than 1:1 magnification the results indicate that focusing is very critical due to the extremely shallow depth of field available with a 400mm f5.6 lens. How do I know that the 500D with a 400mm lens provides greater than 1:1 magnification? The quarter is exactly 24mm in diameter and the D100's CCD is 18mm x 24mm in size, or half the size of a 35mm format frame. As you can see, the 24mm diameter of the quarter spreads past the CCD's frame. If it were really 1:1 magnification, the quarter's diameter would fit perfectly within the horizontal width of the CCD's chip. And to throw another spanner into the thought process, don't forget the 1.5x crop factor of the CCD, so that 200mm becomes effectively 300mm and 400mm becomes 600mm relative to 35mm format. It's not shabby at all for an accessory that can fit in a pocket and be screwed on quickly with results that according to others, can rival true macro lenses and with no loss of light, or in the case of many macro lenses, with the loss of focal length. It is not well known that macro lenses become much less than their nominal focal length due to various optical theories that I have no aptitude for or desire to try and repeat here (okay, quick and dirty of it is that the loss of focal length is due to the internal focus design). The Nikkor 105mm Micro lens becomes about an 80mm lens in the macro range and is only 105mm at infinity focus.
Will the Canon 500D stop me from buying a true macro lens once I can prioritize the necessary discretionary income to buy one? No, but then I did also have the 500D in mind for quick magnification shots during weddings where I can keep it in a small waist bag with the rolls of film and it makes for a much more compact way to travel with a minimum of kit. Trying to get 1:1 with a 2x TC attached to the 70-200 lens is potentially problematic, but it is possible; however, I will likely use it predominantly with the 70-200 lens alone for best results.
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Correspondence & About this website Copyright © 1998-2008 Edwin Leong |
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The
Canon 500D is a thick and heavy lens accessory given that it is meant
to be used like a filter attachment. It is about double the size and
weight of a typical UV filter. The 500 signfies the number of mm of
working distance available when the master lens is set to infinity focus;
however, this working distance is reduced to about 330 mm when I have
my 70-200 lens set for the closest focusing distance. The D signifies
that it is a dual-element achromat, as Canon has a single-element version
known simply as the 500. There are also single and dual-element close-up
lenses known as the 250 and 250D. These close-up lenses obviously signify
a working distance of up to 250 mm and are recommended for use with
lenses in the 50mm to 135mm range (maximum filter diameter available
is 58mm). The 500 lenses are recommended for lenses in the 70mm to 300mm
range.
